Gene Ontology annotation through association of InterPro records with GO terms
Gene Ontology annotation based on Enzyme Commission mapping
Automatic assignment of GO terms using logical inference, based on on inter-ontology links
TreeGrafter-generated GO annotations
Combined Automated Annotation using Multiple IEA Methods
MxiK and MxiN interact with the Spa47 ATPase and are required for transit of the needle components MxiH and MxiI, but not of Ipa proteins, through the type III secretion apparatus of Shigella flexneri.
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A spa47 mutant of S. flexneri is secretion defective and the needle components MxiH and MxiI are drastically reduced. Two-hybrid and immunoprecipitation identify Spa47 interactions with MxiK/SctK and MxiN/SctL.
"we identified interactions between MxiK and Spa33 and Spa47 and between MxiN and Spa33 and Spa47"
Characterization of soluble complexes of the Shigella flexneri type III secretion system ATPase.
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Native Spa47 was characterized from the S. flexneri cytoplasm and shown to be in two distinct high-molecular-weight complexes with Spa33, MxiN and MxiK.
"demonstrating it to be in two distinct high-molecular-weight complexes with Spa33: MxiN and MxiK"
Visualization of the type III secretion sorting platform of Shigella flexneri.
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Cryo-electron tomography and subtomogram averaging of intact S. flexneri injectisomes resolve the cytoplasmic sorting platform as a central hub with six spokes and terminal pods. The hub is a Spa47 hexamer, MxiN forms the spokes and Spa33 the pods, and the hub is aligned with the MxiA export gate channel.
"the hub consists mainly of a hexamer of the Spa47 ATPase, whereas the MxiN protein comprises the spokes and the Spa33 protein forms the pods"
Spa47 is an oligomerization-activated type three secretion system (T3SS) ATPase from Shigella flexneri.
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First purification of active Spa47 and first direct demonstration that it is an ATPase. Multiple oligomeric species were resolved, the largest more than eight-fold more active than the monomer. A Walker A lysine mutant (Lys165) retains oligomerization but is catalytically dead and fails to restore invasion in a spa47 null strain.
"providing the first direct evidence that Spa47 is a bona fide ATPase"
MxiA, MxiC and IpaD Regulate Substrate Selection and Secretion Mode in the T3SS of Shigella flexneri.
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Efficient type III secretion in S. flexneri requires both a cytoplasmic ATPase and the proton motive force, and it is the MxiA/SctV family inner-membrane export apparatus protein and its regulators that are implicated in using the proton motive force for export.
"MxiA family proteins and their regulators are implicated in utilization of the PMF for protein export"
Structural and biochemical characterization of Spa47 provides mechanistic insight into type III secretion system ATPase activation and Shigella virulence regulation.
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High-resolution crystal structures of Spa47 support an activated oligomer in which ATP hydrolysis depends on side chains contributed by adjacent protomers. The tested active-site residues are each essential for ATPase activity without being required for stable oligomer formation. A monomeric N-terminally truncated construct cannot hydrolyze ATP despite an intact catalytic core.
"Spa47 oligomerization and ATP hydrolysis are needed for complete T3SS apparatus formation, a proper translocator secretion profile, and Shigella virulence"
MxiN differentially regulates monomeric and oligomeric species of the Shigella type three secretion system ATPase Spa47.
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MxiN/SctL binding requires the six N-terminal residues of Spa47, the same residues needed for stable oligomer formation and activation, and it up-regulates monomeric Spa47 while down-regulating the oligomer.
"interaction of MxiN with Spa47 requires the six N-terminal residues of Spa47 that are also necessary for stable Spa47 oligomer formation and activation"
Structural insight into conformational changes induced by ATP binding in a type III secretion-associated ATPase from Shigella flexneri.
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Crystal structures of Spa47 with ATPgammaS describe nucleotide recognition, including a catalytic magnesium ion and an ordered water molecule, and a conformational change in a conserved luminal loop on ATP binding.
"a catalytic magnesium ion and an ordered water molecule"
Bacterial type III secretion systems: a complex device for the delivery of bacterial effector proteins into eukaryotic host cells.
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In injectisomes, substrate translocation is mainly fueled by the proton motive force across the inner membrane, and the conserved charged residues implicated in using it lie in the transmembrane domain of SctV. The ATPase contributes dechaperoning, unfolding and efficient coupling to the export gate.
"Substrate translocation itself is mainly fueled by the PMF across the bacterial inner membrane"
Shutting Down Shigella Secretion: Characterizing Small Molecule Type Three Secretion System ATPase Inhibitors.
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Active oligomeric Spa47 was purified and used for kinetic analysis of three noncompetitive inhibitors, which reduce secretion in vivo without disrupting the Spa47 oligomer or preventing apparatus formation.
"the inhibitors do not function through disruption of Spa47 oligomers or by preventing T3SA formation"
Interfacial amino acids support Spa47 oligomerization and shigella type three secretion system activation.
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A model of the activated Spa47 homohexamer identified two protomer interfaces; mutants at these positions fail to oligomerize and to hydrolyze ATP, and lose effector secretion, membrane disruption and invasion in vivo.
"we developed a model of an activated Spa47 homo-hexamer"
Dominant negative effects by inactive Spa47 mutants inhibit T3SS function and Shigella virulence.
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Injectisome incorporation of Spa47 is determined by its N-terminus rather than by ATPase activity, so catalytically inactive mutants still dock and exert a dominant negative effect on T3SS function and Shigella virulence.
"the N-terminus of Spa47, not ATPase activity, is responsible for incorporation into the injectisome"
Falcon deep research report for Shigella flexneri sctN (Spa47)
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Synthesizes the recent literature on Spa47 as a Mg2+-dependent T3SS ATPase whose hydrolysis serves substrate recognition, chaperone release and unfolding rather than membrane transport, with the proton motive force acting through the membrane export machinery.
"hydrolysis supports substrate recognition, chaperone release and substrate unfolding/presentation to the export gate rather than acting as a membrane transporter itself"
Curation notes for Shigella flexneri sctN (Spa47)
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Trace of the PANTHER PTHR15184 node placement for the TreeGrafter GO:0046933 row, showing the IBD sits at the duplication node PTN008558586 ancestral to both the F1-beta clade and the type III export ATPase clade that contains P0A1C1 (PTHR15184:SF9, graft node PTN001807734).
"the IBD was placed one node too deep, at the duplication that separates F1-beta from the T3SS/flagellar export ATPases"