Mitochondrial DNA replisome in Drosophila melanogaster

Mitochondrial DNA is copied by a dedicated replisome in the mitochondrial matrix that is separate from the nuclear replication machinery. DNA polymerase gamma, a heterodimer of the catalytic subunit PolG1 and the accessory subunit PolG2, synthesizes DNA and proofreads it. The mitochondrial replicative helicase (mtDNA-helicase, the ortholog of human Twinkle) unwinds the duplex ahead of the polymerase, and the mitochondrial single-stranded DNA-binding protein mtSSB coats the displaced strand and stimulates both enzymes. Mutations in these genes in Drosophila reduce mtDNA copy number.

MODULE:dmel_mitochondrial_dna_replisomeDRAFTCONCRETEProtein Complexmodules/dmel_mitochondrial_dna_replisome.yaml

replisomeGO:0030894

FB:FBgg0001975

FlyBase gene group MT-REP: Mitochondrial dna replisome

FlyBase release FB2026_03 groups 4 D. melanogaster genes as mitochondrial dna replisome (MT-REP); this module models that group.

GO:0030894

replisome

GO term grounding the module as replisome.

Pol gamma also appears as a part of dmel_dna_polymerase_complexes. The 5'-3' helicase activity is assigned to mtDNA-helicase by conservation with human Twinkle. Mitochondrial RNA polymerase (primer synthesis), topoisomerases and TFAM are outside the module. FlyBase groups realized by this module: MT-REP (FBgg0001975). Participants were generated from the FlyBase gene-group membership and mapped to UniProtKB by projects/FLYBASE_GENE_GROUPS/generate_modules.py from module_specs/dmel_mitochondrial_dna_replisome.yaml. Member genes with a gene review in this repository: mtDNA-helicase, mtSSB, PolG1, PolG2.

4Nodes

3Parts

0Variant Sets

0Variants

3Annotons

2Connections

Derived QC

Recommended-field compliance

100.0% recommended fields populated

All recommended fields populated.

Module deep research

✗ none found

No MODULE:dmel_mitochondrial_dna_replisome deep-research report alongside the module YAML.

Leaf nodes lacking representative members

✓ every leaf node grounds to a representative protein.

Template conformance

✓ every declared conforms_to bundle matches its template motif.

Function consistency and core coverage

3 gene-function check(s) reflected in core functions · 0 conflict(s) · 0 evidence or coverage gap(s) (3 comparison(s))

Retained noncore functions are reported separately; they do not require promotion to core functions. Support from representative genes does not establish conservation across the whole family. Missing reviews or identifiers leave a claim unverified.

Annoton	Participant	Function	Assessment
pol_gamma_complex/polg1	PolG1 UniProtKB:Q27607 Complex Unit	DNA-directed DNA polymerase activity GO:0003887	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
mtdna_helicase_mtdna_helicase	mtDNA-helicase UniProtKB:Q9VL76 Gene	5'-3' DNA helicase activity GO:0043139	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
mtssb_mtssb	mtSSB UniProtKB:P54622 Gene	single-stranded DNA binding GO:0003697	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).

Gene-review completeness (4/4 grounded genes reviewed)

3 complete review(s) · 3 with deep research · 0 missing review · 1 reviewed but lacking deep research

Gene	Review	Complete	Deep research
mtDNA-helicase Q9VL76	✓	✓	✓
mtSSB P54622	✓	✓	✗
PolG1 Q27607	✓	✓	✓
PolG2 Q9VJV8	✓	36/38	✓

Tree

Mitochondrial DNA replisomeProtein Complexdmel_mitochondrial_dna_replisome

Parts
1. 1. mitochondrial DNA polymerase
2. DNA polymerase gammaProtein Complexpol_gamma
  
  Annotons
  - DNA polymerase gamma Protein Complex: DNA polymerase gamma
3. 2. replicative helicase
4. Mitochondrial replicative helicaseProtein Complexmtdna_helicase
  
  Annotons
  - mtDNA-helicase Mitochondrial replicative helicase Gene Product: mtDNA-helicase
5. 3. single-stranded DNA protection
6. Mitochondrial single-stranded DNA-binding proteinProtein Complexmtssb
  
  Annotons
  - mtSSB Mitochondrial single-stranded DNA-binding protein Gene Product: mtSSB

Details

Context

Drosophila melanogasterNCBITaxon:7227

mitochondrial nucleoidGO:0042645

Mitochondrial DNA replisomeProtein Complexdmel_mitochondrial_dna_replisome

Pol gamma, the Twinkle-family helicase and mtSSB that together replicate mitochondrial DNA.

replisomeGO:0030894

Context

Drosophila melanogasterNCBITaxon:7227

mitochondrial nucleoidGO:0042645

Connections

mtdna_helicase -> pol_gamma Provides Input For

The helicase unwinds the template that Pol gamma copies.

mtssb -> pol_gamma Positively Regulates

mtSSB coats displaced single strands and stimulates DNA synthesis.

Part 1: mitochondrial DNA polymerase

DNA polymerase gammaProtein Complexpol_gamma

Annotons

DNA polymerase gamma

pol_gamma_complex

Participant: Protein Complex: DNA polymerase gamma

Protein Complex:

DNA polymerase gammaGO:0005760

Active units:

PolG1

Participant: Gene Product: PolG1

Gene Product:

PolG1UniProtKB:Q27607

Function:

DNA-directed DNA polymerase activityGO:0003887

PolG2

Participant: Gene Product: PolG2

Gene Product:

PolG2UniProtKB:Q9VJV8

Processes

mitochondrial DNA replicationGO:0006264

Part 2: replicative helicase

Mitochondrial replicative helicaseProtein Complexmtdna_helicase

Annotons

mtDNA-helicase Mitochondrial replicative helicase

mtdna_helicase_mtdna_helicase

Participant: Gene Product: mtDNA-helicase

Gene Product:

mtDNA-helicaseUniProtKB:Q9VL76

Function

5'-3' DNA helicase activityGO:0043139

Processes

mitochondrial DNA replicationGO:0006264

Part 3: single-stranded DNA protection

Mitochondrial single-stranded DNA-binding proteinProtein Complexmtssb

Annotons

mtSSB Mitochondrial single-stranded DNA-binding protein

mtssb_mtssb

Participant: Gene Product: mtSSB

Gene Product:

mtSSBUniProtKB:P54622

Function

single-stranded DNA bindingGO:0003697

Processes

mitochondrial DNA replicationGO:0006264