mcm-4 encodes the C. elegans ortholog of MCM4, a subunit of the heterohexameric
MCM2-7 pre-replication complex / replicative helicase. As part of the CMG
(CDC45–MCM–GINS) helicase it unwinds template DNA during S-phase. Conserved
roles: replication licensing, DNA synthesis (elongation), and the DNA replication
checkpoint coupling M-phase entry to S-phase completion.
Falcon deep research (just deep-research-falcon worm mcm-4 --fallback perplexity-lite)
was launched in parallel with publication caching. The wrapper reported a 600s timeout
(and the perplexity-lite fallback was unavailable in this environment), but falcon in
fact completed after ~1406s and wrote mcm-4-deep-research-falcon.md (51 citations) plus
artifacts. The report corroborates the entire review: it confirms the
lin-6/let-358 = mcm-4 = MCM4 identity, the complex-level ATPase/helicase activities
(incl. the MCM4/6/7 subcomplex biochemistry), the replication checkpoint role, the
epidermis-specific requirement, and the nuclear→diffuse(NEBD)→late-anaphase chromatin
localization dynamics. No annotation decision needed changing.
New context (not annotation-changing): a 2024 study (Memar et al., Nat Commun) reports a
replication-independent role for the CMG helicase in asymmetric cell-fate divergence
(via the GINS subunit PSF-2, not mcm-4 directly), proposed to act through
chromatin/histone handling at the egl-1 locus. Captured as a new suggested_question and
noted in the deep-research reference_review; MCM-4's strongest evidence remains canonical
licensing/helicase. The deep-research file is now cited (additional_reference_ids +
supported_by) on the ssDNA helicase activity annotation.
Wove the deep-research findings into the relevant annotations beyond the single
ssDNA-helicase citation:
- DNA helicase activity (GO:0003678, IEA) and ATP hydrolysis (GO:0016887, IEA): added
the MCM4/6/7 subcomplex biochemistry (intrinsic ssDNA-dependent ATP hydrolysis;
ATPase/helicase with ATP hydrolysis in the MCM ring driving translocation/unwinding).
- nucleus (GO:0005634, IDA) and chromosome (GO:0005694, EXP): added the cell-cycle
localization dynamics (nuclear interphase → diffuse at NEBD → not on metaphase
chromatin → reassociates in late anaphase).
- Added Ruijtenberg, van den Heuvel & The 2011 (doi:10.5772/19397) to references,
surfaced by deep research; marked correctness=UNVERIFIED because it has no PMID, is
not in the GOA, and was not independently retrieved/read in this review.
All deep-research supporting_text quotes validate against the cached report.
Reviewer correctly flagged that the original supporting_text quoted the NMAD-1/TOP-2
in vivo co-IP and the summary wrongly implied MCM-4 co-IP. Verified from PMID:31283754
full text:
- MCM-4 identified in NMAD-1 IP/MS as a candidate binder.
- NMAD-1 binds MCM-4 directly in vitro (recombinant His-NMAD-1 pulldown of MCM-4;
Fig 4B / S5). PMID:31283754
- In vivo interaction with MCM-4 was not confirmed; only NMAD-1/TOP-2 confirmed in
vivo. PMID:31283754
Corrected the annotation summary/reason and supporting_text accordingly (in vitro direct
binding cited; in vivo caveat stated), and refined the PMID:31283754 reference finding.
Action remains KEEP_AS_NON_CORE (uninformative MF term; in vitro direct binding still
supports the IPI).
Context: requested as the experimentally characterised same-gene relative of the ProtNLM2
benchmark fragment CAEEL/A0A061AL94 (residues 750-823 of Q95XQ8, the C-terminal WHD
region). No ProtNLM2 output was opened or used.
Folder: the task named genes/CAEEL/mcm-4, but this gene already has a complete review at
genes/worm/mcm-4, the canonical C. elegans directory that projects/IBA_REVIEW refers to.
just fetch-gene CAEEL mcm-4 created a duplicate stub (3 files, never committed). I
removed it and re-reviewed this folder instead, so Q95XQ8 keeps a single review.
Inputs refreshed with just fetch-gene worm mcm-4 --force (UniProt entry v180, GOA 28
rows). GOA changes since the last review: a new IBA is_active_in nucleus
(PTN000179712), and the nucleus IEA now comes from GO_REF:0000120 (ARBA + SubCell)
instead of GO_REF:0000044. The stale GO_REF:0000044 nucleus row is no longer in GOA, so I
dropped it from the review.
Deep research: just deep-research-falcon CAEEL mcm-4 --fallback perplexity-lite failed
(Edison "Failed to authenticate"; the perplexity-lite fallback timed out after 600 s). The
existing mcm-4-deep-research-falcon.md from the earlier review is still used. Primary
evidence was re-read from the full text of PMID:21146520 and PMID:31283754.
Evolutionary grounding:
- PANTHER PTHR11630:SF66 (MCM4 subfamily) [UniProt DR line]. IBA nodes:
PTN000179711 (MCM2-7 clade: MCM complex, ssDNA binding, ssDNA helicase contributes_to),
PTN000179968 (eukaryotic MCM4 node, taxon:2759: strand elongation, mitotic replication
initiation, BIR; seeds yeast Mcm4 SGD:S000006223 [verified via SGD API = MCM4/YPR019W]
and S. pombe cdc21), PTN000179712 (nucleus). See interpro/panther/PTHR11630/PTHR11630-paint.tsv.
The IRD negations in that file are on other branches (taxon 7227 and 33511 nodes), not
on the MCM4 lineage.
- ISS donor P49717 is mouse MCM4, in the same subfamily.
- Catalytic motifs are intact (new analysis, mcm-4-bioinformatics/motif_check_rereview.py,
RESULTS-rereview.md): Walker A 469-476 GDPGTSKS, Walker B 533-536 DEFD, SRF at 601.
What is experimental in C. elegans and what is inferred:
- Experimental (PMID:21146520): nuclear localization (immunostaining, RNAi- and
mutant-controlled); chromatin association from late anaphase, absent from condensed
prophase, metaphase and meiosis I chromosomes; required for postembryonic somatic DNA
synthesis (BrdU/EdU; e1466 behaves as null over tDf3) and for embryonic DNA replication
(RNAi); cell-autonomous for DNA synthesis and endoreduplication (elt-2 rescue);
needed for the rnr-1/HU-induced checkpoint delay; epidermal (dpy-7) expression rescues
growth and viability. In vitro direct binding to NMAD-1 (PMID:31283754), not confirmed in vivo.
- Inferred only (orthology/PAINT plus motifs): MCM2-7 complex membership as a physical
fact, ssDNA binding, ATP hydrolysis, ssDNA helicase contribution, and the specific
roles in initiation, elongation and BIR. No C. elegans biochemistry exists.
Action changes from the previous review, and why:
- BIR IBA: MARK_AS_OVER_ANNOTATED → KEEP_AS_NON_CORE. The IBA node placement is sound and
the MCM helicase does the unwinding in BIR. The only objection had been the lack of
worm-specific data, which is not a valid challenge to an IBA.
- DNA binding IEA → MODIFY to ssDNA binding. DNA helicase activity (IEA and ISS) → MODIFY
to GO:0017116, keeping contributes_to semantics. DNA replication IEA → MODIFY to
mitotic replication initiation plus strand elongation. DNA replication initiation IEA →
MODIFY to GO:1902975. Chromosome (EXP and IEA) → MODIFY to GO:0000785 chromatin, which
is what the paper observes. All ancestor relations were checked with OLS
hierarchicalAncestors.
- Protein binding IPI: KEEP_AS_NON_CORE → REMOVE, per the GO:0005515 policy.
- Nervous system development, gonad development, locomotion (IMP, PMID:7262539):
KEEP_AS_NON_CORE → MARK_AS_OVER_ANNOTATED. These are downstream consequences of failed
DNA synthesis in dividing blast cells (necessity, not participation). Not REMOVE, because
the original paper is abstract-only here.
- Core functions rewritten: contributes_to ssDNA helicase in the MCM complex (nucleus and
chromatin), and ATP hydrolysis. I dropped the earlier "checkpoint" core function, which
had been attached to the generic DNA replication term. Whether the checkpoint
requirement is direct signalling or simply the absence of forks to signal from is now a
suggested question; no GO term is proposed for it.
For transfer to the fragment A0A061AL94: it covers only residues 750-823, after the AAA+
domain (400-735). It contains none of the Walker A/B or SRF catalytic motifs, so
catalytic or helicase claims cannot be assessed from the fragment sequence alone. Any
transfer rests on its being the same gene (WBGene00003156).