srfA

id: Q54TY7
gene_symbol: srfA
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:44689
  label: Dictyostelium discoideum
description: SrfA (DdSRF) is the Dictyostelium discoideum homolog of Serum Response
  Factor, a MADS-box transcription factor. Its MADS-box DNA-binding domain (residues
  67-127) is highly conserved with the human, Drosophila and yeast SRF homologs,
  although several DNA-binding residues have diverged, likely altering its
  target-sequence specificity relative to animal SRFs (the animal CArG box is not
  found in its Dictyostelium targets). SrfA acts in the nucleus as a sequence-specific
  RNA polymerase II transcription factor that activates a subset of late,
  prespore/spore-specific genes (for example the spore-coat marker spiA and the
  SrfA-dependent sigA/sigB/sigC/sigD genes). It is expressed in a complex,
  promoter-dependent pattern across prestalk, prespore and spore cells, with a strong
  induction in prespore cells at culmination that is driven by cAMP-dependent protein
  kinase A (PKA). SrfA is essential for terminal spore differentiation and maturation,
  since srfA-null strains form rounded spores with reduced viability, defective
  actin-rod formation, and progressively degrading spore coats, and the mutants also
  show defective slug migration and a delay in culmination.
existing_annotations:
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: Nuclear localization is where a sequence-specific transcription factor
      acts. Consistent with the MADS-box/SRF family and with the independent IC and
      UniProt-based nucleus annotations for this protein.
    action: ACCEPT
    reason: SrfA is a MADS-box RNA polymerase II transcription factor; the nucleus is
      its site of action. This is well supported across evidence types.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: A homolog of the Serum Response Factor (SRF) has been isolated
        from Dictyostelium discoideum
- term:
    id: GO:0000978
    label: RNA polymerase II cis-regulatory region sequence-specific DNA binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: SrfA is a MADS-box protein that binds cis-regulatory regions of target
      genes; the SrfA-dependent sig genes are proposed to be directly activated through
      binding to their promoters. Note that DNA-binding residues have diverged from
      animal SRF, so the recognized element likely differs from the animal CArG box.
    action: ACCEPT
    reason: Sequence-specific cis-regulatory DNA binding is the core biochemical
      activity of a MADS-box/SRF transcription factor and is consistent with the
      proposed direct promoter binding of SrfA targets.
    supported_by:
    - reference_id: PMID:14665466
      supporting_text: The regulation of the expression of sig genes by SrfA could be
        through direct binding to their promoters, which activates their expression
- term:
    id: GO:0000981
    label: DNA-binding transcription factor activity, RNA polymerase II-specific
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: This is the core molecular function of SrfA - a sequence-specific RNA
      polymerase II DNA-binding transcription factor of the MADS-box/SRF family,
      corroborated by experimental IMP evidence (GO:0003700).
    action: ACCEPT
    reason: SrfA is an SRF-family MADS-box transcription factor that activates RNA
      polymerase II transcription of late developmental genes. This is its defining
      function.
    supported_by:
    - reference_id: PMID:14665466
      supporting_text: The MADS box transcription factor SrfA is required for spore
        differentiation in Dictyostelium discoideum
- term:
    id: GO:0045944
    label: positive regulation of transcription by RNA polymerase II
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: SrfA induces (activates) the expression of spore-specific genes at the
      final steps of spore differentiation; five SrfA-dependent genes are not expressed
      in srfA-null strains, consistent with a positive/activating role.
    action: ACCEPT
    reason: Experimental data show SrfA is required for the expression of its target
      genes and induces spore-specific genes, supporting a positive-regulation role.
    supported_by:
    - reference_id: PMID:14665466
      supporting_text: These data are in agreement with the hypothesis that SrfA
        induces the expression of a number of spore-specific genes at the final steps
        of spore differentiation
- term:
    id: GO:0000981
    label: DNA-binding transcription factor activity, RNA polymerase II-specific
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: InterPro2GO annotation from the SRF-like MADS-box domain (IPR033897).
      Redundant with the IBA and experimental (IMP/ISS) transcription-factor
      annotations and biologically correct.
    action: ACCEPT
    reason: The SRF-like MADS-box domain is a well-characterized RNA polymerase II
      DNA-binding transcription factor domain; the electronic inference is correct and
      matches experimental evidence.
    supported_by:
    - reference_id: PMID:14665466
      supporting_text: The MADS box transcription factor SrfA is required for spore
        differentiation in Dictyostelium discoideum
- term:
    id: GO:0000987
    label: cis-regulatory region sequence-specific DNA binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: InterPro2GO annotation for sequence-specific cis-regulatory DNA binding.
      Correct but more general than the RNA polymerase II-specific term (GO:0000978)
      also annotated to this protein.
    action: ACCEPT
    reason: SrfA binds cis-regulatory regions of its targets. The annotation is
      biologically correct; the Pol II-specific child term is the more informative
      version of the same activity.
    supported_by:
    - reference_id: PMID:14665466
      supporting_text: The regulation of the expression of sig genes by SrfA could be
        through direct binding to their promoters, which activates their expression
- term:
    id: GO:0003677
    label: DNA binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: General DNA binding inferred from the MADS-box domain. Correct but
      uninformative given the more specific sequence-specific and RNA polymerase
      II-specific DNA-binding terms already annotated.
    action: KEEP_AS_NON_CORE
    reason: DNA binding is a true but very general parent term. The specific
      sequence-specific transcription-factor DNA-binding terms better capture the core
      function, so this general term is retained as non-core.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: The MADS-box region of Dictyostelium SRF (DdSRF) is highly
        conserved with those of the human, Drosophila and yeast homologs
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Nuclear localization from the UniProt subcellular-location mapping,
      consistent with the transcription-factor function and the IC and IBA nucleus
      annotations.
    action: ACCEPT
    reason: SrfA is a nuclear transcription factor; nuclear localization is well
      supported across multiple evidence lines.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: A homolog of the Serum Response Factor (SRF) has been isolated
        from Dictyostelium discoideum
- term:
    id: GO:0045944
    label: positive regulation of transcription by RNA polymerase II
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: involved_in
  review:
    summary: InterPro2GO inference of positive regulation of RNA polymerase II
      transcription from the SRF-like domain. Redundant with the IBA annotation and
      supported by experimental data showing SrfA induces target-gene expression.
    action: ACCEPT
    reason: Consistent with experimental evidence that SrfA activates its target
      genes; the electronic inference matches the biology.
    supported_by:
    - reference_id: PMID:14665466
      supporting_text: These data are in agreement with the hypothesis that SrfA
        induces the expression of a number of spore-specific genes at the final steps
        of spore differentiation
- term:
    id: GO:0046983
    label: protein dimerization activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: MADS-box/SRF proteins bind DNA as dimers, so dimerization activity is a
      plausible domain-based inference. However there is no direct experimental
      evidence for SrfA dimerization, and it is an ancillary capability supporting DNA
      binding rather than a core function.
    action: KEEP_AS_NON_CORE
    reason: Dimerization is a general property of the MADS-box fold that supports DNA
      binding, but it is an accessory biochemical capability inferred only from domain
      presence, not a core evolved function of SrfA.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: The MADS-box region of Dictyostelium SRF (DdSRF) is highly
        conserved with those of the human, Drosophila and yeast homologs
- term:
    id: GO:0031247
    label: actin rod assembly
  evidence_type: IMP
  original_reference_id: PMID:14706699
  qualifier: involved_in
  review:
    summary: srfA-null spores fail to form mature actin rods and show strongly reduced
      actin phosphorylation. This is a genuine mutant phenotype, but it is a downstream
      consequence of SrfA's transcriptional function rather than a direct molecular
      role of SrfA in rod assembly.
    action: KEEP_AS_NON_CORE
    reason: The phenotype is well documented experimentally, but SrfA is a
      transcription factor acting upstream; the actin-rod defect reflects loss of
      target-gene expression. Retained as a non-core, downstream developmental role.
    supported_by:
    - reference_id: PMID:14706699
      supporting_text: SrfA mutant spores showed the initial stages of rod formation
        but no mature rods were found in older spores either in the nucleus or the
        cytoplasm
    - reference_id: PMID:14706699
      supporting_text: phosphorylation of actin, that is believed to stabilize the
        actin rods, is strongly reduced in the mutant
- term:
    id: GO:0042244
    label: spore wall assembly
  evidence_type: IMP
  original_reference_id: PMID:14706699
  qualifier: involved_in
  review:
    summary: srfA-null spores form basically normal trilaminar coats initially but the
      outer layer becomes wavier and progressively degrades as the spore ages,
      indicating a late defect in spore-coat stability. As with actin rods, this is a
      downstream effect of the loss of SrfA-dependent transcription.
    action: KEEP_AS_NON_CORE
    reason: The spore-coat stability defect is experimentally supported, but SrfA acts
      as an upstream transcription factor; the coat phenotype is an indirect
      consequence. Retained as a non-core developmental role.
    supported_by:
    - reference_id: PMID:14706699
      supporting_text: the outer layer gets wavier as the spore ages and suffers a
        progressive degradation suggesting a late defect in the stability of the spore
        coat
- term:
    id: GO:0043945
    label: positive regulation of asexual sporulation resulting in formation of a
      cellular spore
  evidence_type: IMP
  original_reference_id: PMID:14706699
  qualifier: involved_in
  review:
    summary: SrfA is required for late events of spore maturation and for full spore
      viability, and it positively drives expression of spore-specific genes. This
      captures its regulatory role in sporulation.
    action: ACCEPT
    reason: SrfA is essential for spore differentiation/maturation and positively
      regulates spore-gene expression; a positive-regulation-of-sporulation term is
      appropriate and reflects a core aspect of its biology.
    supported_by:
    - reference_id: PMID:14706699
      supporting_text: these results suggest that SrfA is involved in late events of
        spore maturation necessary for spore stability
- term:
    id: GO:0006357
    label: regulation of transcription by RNA polymerase II
  evidence_type: IMP
  original_reference_id: PMID:14665466
  qualifier: involved_in
  review:
    summary: This study isolated five SrfA-dependent genes that are expressed in
      wild-type but not srfA-null strains, directly demonstrating that SrfA regulates
      RNA polymerase II transcription of target genes.
    action: ACCEPT
    reason: Direct experimental evidence that SrfA is required for the expression of a
      defined set of target genes supports its role in regulation of RNA polymerase II
      transcription.
    supported_by:
    - reference_id: PMID:14665466
      supporting_text: Five genes whose expression is dependent on SrfA have been
        isolated by differential hybridization
- term:
    id: GO:0006357
    label: regulation of transcription by RNA polymerase II
  evidence_type: ISS
  original_reference_id: PMID:9729488
  qualifier: involved_in
  review:
    summary: Sequence-similarity inference from human SRF (UniProtKB:P11831). SrfA's
      MADS-box is highly conserved with the human, Drosophila and yeast homologs,
      supporting a conserved transcription-factor role.
    action: ACCEPT
    reason: The conserved MADS-box and demonstrated target-gene dependence support the
      transcription-factor role transferred by similarity from human SRF.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: The MADS-box region of Dictyostelium SRF (DdSRF) is highly
        conserved with those of the human, Drosophila and yeast homologs
- term:
    id: GO:0006357
    label: regulation of transcription by RNA polymerase II
  evidence_type: IMP
  original_reference_id: PMID:9729488
  qualifier: involved_in
  review:
    summary: srfA disruption reduces expression of the spore marker spiA and impairs
      spore maturation, indicating SrfA regulates the transcription of target genes.
    action: ACCEPT
    reason: Loss-of-function evidence that SrfA is needed for target-gene (spiA)
      expression supports its role in regulation of RNA polymerase II transcription.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: participates in the regulation of the expression of the
        spore-coat marker spiA
- term:
    id: GO:0042331
    label: phototaxis
  evidence_type: IMP
  original_reference_id: PMID:11437439
  qualifier: acts_upstream_of_or_within
  review:
    summary: srfA-null strains have a slug-migration defect; phototaxis is a
      slug-migration-associated behavior assessed in this study of srfA's developmental
      roles. This is a downstream, non-core developmental phenotype of the
      transcription factor.
    action: KEEP_AS_NON_CORE
    reason: SrfA acts upstream of slug behaviors as a transcription factor. The
      phototaxis/migration phenotype is a real but indirect developmental role, not
      the core molecular function. Experimental IMP annotation retained as non-core.
    supported_by:
    - reference_id: PMID:11437439
      supporting_text: The study of knockout strains revealed that srfA is also
        required for proper slug migration
- term:
    id: GO:0031154
    label: culmination involved in sorocarp development
  evidence_type: IEP
  original_reference_id: PMID:25887420
  qualifier: acts_upstream_of_or_within
  review:
    summary: This is a genome-wide developmental transcriptome study (Rosengarten et
      al. 2015) that profiles thousands of genes but does not specifically discuss
      srfA in the available text. The culmination association is an expression-pattern
      (IEP) inference that cannot be verified for srfA from this source.
    action: UNDECIDED
    reason: The cited large-scale transcriptome paper does not mention srfA in the
      cached text, so its specific contribution to culmination cannot be verified here.
      SrfA's culmination-stage role is separately supported by other references (its
      PKA-driven induction and expression in prespore cells at culmination), but this
      particular IEP annotation cannot be independently confirmed.
- term:
    id: GO:0031154
    label: culmination involved in sorocarp development
  evidence_type: IMP
  original_reference_id: PMID:11437439
  qualifier: acts_upstream_of_or_within
  review:
    summary: SrfA is expressed in a complex pattern that includes strong induction in
      spores by the end of culmination, and srfA is required for several developmental
      functions. Its role at culmination is a developmental, non-core function
      downstream of its transcription-factor activity.
    action: KEEP_AS_NON_CORE
    reason: Experimental (IMP) annotation of a developmental-stage role. SrfA acts
      upstream as a transcription factor; culmination involvement is a non-core
      developmental role rather than its core molecular function.
    supported_by:
    - reference_id: PMID:11437439
      supporting_text: the correct spatial and temporal pattern of expression of srfA
        is essential for the different functions that this transcription factor plays
        in development
- term:
    id: GO:0030435
    label: sporulation resulting in formation of a cellular spore
  evidence_type: IMP
  original_reference_id: PMID:14706699
  qualifier: acts_upstream_of_or_within
  review:
    summary: SrfA is required for late events of spore maturation necessary for spore
      stability; srfA-null spores are abnormal and lose viability. Sporulation is the
      central biological process in which SrfA acts.
    action: ACCEPT
    reason: Sporulation/spore differentiation is the core developmental process
      requiring SrfA, supported by multiple loss-of-function studies.
    supported_by:
    - reference_id: PMID:14706699
      supporting_text: these results suggest that SrfA is involved in late events of
        spore maturation necessary for spore stability
- term:
    id: GO:0003700
    label: DNA-binding transcription factor activity
  evidence_type: IMP
  original_reference_id: PMID:9729488
  qualifier: enables
  review:
    summary: Experimental (IMP) support for SrfA acting as a DNA-binding transcription
      factor, based on the requirement of srfA for target-gene (spiA) expression. The
      RNA polymerase II-specific child term (GO:0000981) is the more precise form of
      the same activity.
    action: ACCEPT
    reason: DNA-binding transcription factor activity is the core molecular function of
      SrfA and is experimentally supported by its requirement for target-gene
      expression.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: participates in the regulation of the expression of the
        spore-coat marker spiA
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IC
  original_reference_id: PMID:9729488
  qualifier: located_in
  review:
    summary: Nuclear localization inferred by curators (IC) from the DNA-binding
      transcription factor activity of SrfA. Consistent with the IBA and UniProt
      nucleus annotations.
    action: ACCEPT
    reason: As a MADS-box transcription factor, SrfA acts in the nucleus; the IC
      inference is sound and corroborated by independent evidence.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: A homolog of the Serum Response Factor (SRF) has been isolated
        from Dictyostelium discoideum
- term:
    id: GO:0030435
    label: sporulation resulting in formation of a cellular spore
  evidence_type: IMP
  original_reference_id: PMID:9729488
  qualifier: acts_upstream_of_or_within
  review:
    summary: srfA disruption causes abnormal spore morphology and loss of viability,
      establishing an essential role in sporulation. Duplicate process annotation
      supported by the original characterization of the gene.
    action: ACCEPT
    reason: Sporulation is the core developmental process requiring SrfA; this
      loss-of-function evidence directly supports the annotation.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: This gene plays an essential role in sporulation as its
        disruption leads to abnormal spore morphology and loss of viability
- term:
    id: GO:0003700
    label: DNA-binding transcription factor activity
  evidence_type: ISS
  original_reference_id: PMID:9729488
  qualifier: enables
  review:
    summary: Sequence-similarity inference of DNA-binding transcription factor activity
      from human SRF (UniProtKB:P11831), consistent with the highly conserved MADS-box
      domain and the experimental IMP annotation of the same activity.
    action: ACCEPT
    reason: The conserved MADS-box supports transfer of the DNA-binding
      transcription-factor activity from human SRF; this is the core molecular function
      of SrfA.
    supported_by:
    - reference_id: PMID:9729488
      supporting_text: The MADS-box region of Dictyostelium SRF (DdSRF) is highly
        conserved with those of the human, Drosophila and yeast homologs
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: PMID:9729488
  title: A Serum Response Factor homolog is required for spore differentiation in
    Dictyostelium.
  findings:
  - statement: DdSRF is the Dictyostelium SRF homolog with a MADS-box highly conserved
      with human, Drosophila and yeast SRFs.
    supporting_text: The MADS-box region of Dictyostelium SRF (DdSRF) is highly
      conserved with those of the human, Drosophila and yeast homologs
  - statement: srfA is expressed in prespore and spore cells and is essential for
      sporulation; disruption causes abnormal spores and loss of viability.
    supporting_text: This gene plays an essential role in sporulation as its
      disruption leads to abnormal spore morphology and loss of viability
  - statement: SrfA participates in regulating expression of the spore-coat marker
      spiA and other maturation genes.
    supporting_text: participates in the regulation of the expression of the
      spore-coat marker spiA
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Original characterization of srfA; establishes it as an SRF/MADS-box
      transcription factor required for spore differentiation. Abstract-only in cache.
- id: PMID:11437439
  title: The MADS-box gene srfA is expressed in a complex pattern under the control
    of alternative promoters and is essential for different aspects of Dictyostelium
    development.
  findings:
  - statement: srfA is expressed in a complex, cell-type-specific pattern via
      alternative promoters across most cell types.
    supporting_text: srfA displays a complex temporal and cell type-specific pattern
      of expression in Dictyostelium
  - statement: srfA is required for proper slug migration in addition to spore
      differentiation.
    supporting_text: The study of knockout strains revealed that srfA is also
      required for proper slug migration
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Establishes expression pattern and additional developmental roles
      (slug migration) beyond sporulation. Abstract-only in cache.
- id: PMID:14665466
  title: Dictyostelium discoideum developmentally regulated genes whose expression
    is dependent on MADS box transcription factor SrfA.
  findings:
  - statement: SrfA is a MADS-box transcription factor required for spore
      differentiation in D. discoideum.
    supporting_text: The MADS box transcription factor SrfA is required for spore
      differentiation in Dictyostelium discoideum
  - statement: Five SrfA-dependent genes were identified that are not expressed in
      srfA-null strains.
    supporting_text: Five genes whose expression is dependent on SrfA have been
      isolated by differential hybridization
  - statement: SrfA induces spore-specific genes at the final steps of spore
      differentiation, possibly by direct promoter binding.
    supporting_text: The regulation of the expression of sig genes by SrfA could be
      through direct binding to their promoters, which activates their expression
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Full text available; identifies SrfA-dependent target genes and
      supports the positive-regulation transcription-factor role.
- id: PMID:14706699
  title: The MADS-box transcription factor SrfA is required for actin cytoskeleton
    organization and spore coat stability during Dictyostelium sporulation.
  findings:
  - statement: srfA-null spores fail to form mature actin rods.
    supporting_text: SrfA mutant spores showed the initial stages of rod formation
      but no mature rods were found in older spores either in the nucleus or the
      cytoplasm
  - statement: The spore coat outer layer progressively degrades in srfA mutants,
      indicating a late spore-coat stability defect.
    supporting_text: the outer layer gets wavier as the spore ages and suffers a
      progressive degradation suggesting a late defect in the stability of the spore
      coat
  - statement: SrfA is involved in late events of spore maturation necessary for
      spore stability.
    supporting_text: these results suggest that SrfA is involved in late events of
      spore maturation necessary for spore stability
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Structural analysis of srfA-null spores; documents actin-rod and
      spore-coat phenotypes downstream of the transcription-factor function.
- id: PMID:12204259
  title: Regulated expression of the MADS-box transcription factor SrfA mediates
    activation of gene expression by protein kinase A during Dictyostelium
    sporulation.
  findings:
  - statement: PKA activation during culmination induces srfA expression in prespore
      cells, placing srfA downstream of PKA in spore maturation.
    supporting_text: Our results strongly suggest that PKA activation during
      culmination leads to the induction of the expression of srfA
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Establishes PKA-dependent regulation of srfA induction at
      culmination; contextual background for its developmental role. Abstract-only in
      cache.
- id: PMID:25887420
  title: Leaps and lulls in the developmental transcriptome of Dictyostelium
    discoideum.
  findings: []
  reference_review:
    relevance: LOW
    correctness: MISCITED
    review_notes: Genome-wide developmental transcriptome study that does not
      specifically discuss srfA in the cached full text. It is cited as the IEP source
      for a culmination annotation, but srfA cannot be verified from this reference.
core_functions:
- description: SrfA is a MADS-box/SRF-family sequence-specific RNA polymerase II
    transcription factor that acts in the nucleus to positively regulate transcription
    of a subset of late, prespore/spore-specific genes (e.g. spiA and the
    SrfA-dependent sig genes), thereby driving terminal spore differentiation and
    maturation during Dictyostelium development.
  molecular_function:
    id: GO:0000981
    label: DNA-binding transcription factor activity, RNA polymerase II-specific
  locations:
  - id: GO:0005634
    label: nucleus
  directly_involved_in:
  - id: GO:0045944
    label: positive regulation of transcription by RNA polymerase II
  - id: GO:0030435
    label: sporulation resulting in formation of a cellular spore
  supported_by:
  - reference_id: PMID:14665466
    supporting_text: These data are in agreement with the hypothesis that SrfA induces
      the expression of a number of spore-specific genes at the final steps of spore
      differentiation
  - reference_id: PMID:9729488
    supporting_text: This gene plays an essential role in sporulation as its
      disruption leads to abnormal spore morphology and loss of viability