Wss1 (SPAC521.02) is a nuclear DNA-dependent zinc metalloprotease of the WLM (Wss1-like metalloprotease) family. It has an N-terminal WLM protease domain with an HExxH...H zinc-binding active site and a C-terminal SUMO-interaction motif. It belongs to the same PANTHER subfamily as budding-yeast Wss1, which proteolyses proteins covalently trapped on DNA, such as topoisomerase 1 cleavage complexes and formaldehyde-induced DNA-protein crosslinks, in a DNA-dependent manner. Fission-yeast wss1 deletion mutants are sensitive to formaldehyde and acetaldehyde and show replication defects, which is consistent with a conserved role in DNA-protein crosslink repair. In that role, proteolysis reduces the crosslinked protein to a small adduct that downstream repair and lesion-bypass pathways can process. The fission-yeast enzyme has not been assayed biochemically. Its paralog Wss2 (Wss1b) sits in a separate PANTHER family.
Summary: Core catalytic activity, transferred from budding-yeast Wss1 (P38838), which has IDA/IMP evidence for DNA-dependent metalloendopeptidase activity. Both proteins are in PANTHER subfamily PTHR46622:SF1, and both keep the HExxH...H zinc site with the same spacing.
Reason: The donor's experimental activity (PMID:24998930) is the defining Wss1 function. The transfer is grounded at the subfamily level, because Q9P7B5 and P38838 are both PTHR46622:SF1, not merely best hits. The catalytic Glu and three zinc-ligand histidines are conserved (H96/E97/H100/H106 vs P38838 H115/E116/H119/H125). The fission-yeast paralog Wss2/Wss1b is in a different PANTHER family (PTHR47795), so data on that protein were not used for this transfer.
HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ...
ACCEPT
Summary: Nuclear localization of tagged Wss1 in the fission-yeast ORFeome localization screen. This is the site where a DNA-protein crosslink protease must act.
Reason: The localization is target-specific, from the genome-wide YFP-fusion localization study, and the reviewed UniProt record cites it. It agrees with the DNA-dependent function. Nuclear is as precise as the evidence allows; there is no data for chromatin or lesion-site recruitment in S. pombe.
Supporting Evidence:
file:SCHPO/wss1/wss1-uniprot.txt
CC -!- SUBCELLULAR LOCATION: Nucleus {ECO:0000269|PubMed:16823372}.
Summary: Correct, but a broad ancestor of the specific process the gene already carries, protein-DNA covalent cross-linking repair (GO:0106300).
Reason: The PAINT inference is sound, because the target is in the Wss1 subfamily and the S. pombe deletion is sensitive to DPC-inducing aldehydes. The evidence supports the specific repair pathway, so the term should be refined to GO:0106300, which is_a GO:0006281 and is already on this gene by ISO.
Propagation Review
Root cause:TERM SCOPING PROBLEM
Failure modes:GRANULARITY MISMATCH
Sources checked:
PANTHER:PTN001503361SUPPORTS TRANSFER
Wss1-clade PAINT node; the target (PTHR46622:SF1) descends from it. The propagated term is correct but broader than the specific term the gene already carries.
Summary: Correct, but a parent of metalloendopeptidase activity (GO:0004222), which the gene already carries by ISO with subfamily-level support.
Reason: The PAINT ancestral activity is sound. Wss1 cleaves internal peptide bonds of DNA-bound proteins (an endopeptidase, EC 3.4.24.-), so the specific child term GO:0004222, already on this gene, is warranted.
Propagation Review
Root cause:TERM SCOPING PROBLEM
Failure modes:GRANULARITY MISMATCH
Sources checked:
PANTHER:PTN001503361SUPPORTS TRANSFER
Wss1-clade PAINT node; the target (PTHR46622:SF1) descends from it. The propagated term is correct but broader than the specific term the gene already carries.
Summary: A curated transfer of the budding-yeast Wss1 IDA/IMP annotation (PMID:24998930). Wss1 does not synthesize DNA. Its contribution is to reduce the protein adduct so that the lesion becomes bypassable. This is peripheral to its core proteolytic repair role.
Reason: The donor annotation is experimental, from a paper whose full text is not cached, and the orthology is subfamily-level. Removing it would overrule the curator without the evidence they used. However, GO:0019985 describes synthesis across a lesion by a specialized polymerase. Wss1 acts upstream by proteolysing the crosslinked protein, so this is kept as a non-core, pathway-context annotation rather than core function. The S. pombe genetic data link wss1 to aldehyde tolerance but do not separately test a TLS role.
Summary: The core process. Budding-yeast Wss1 (same PANTHER subfamily, SF1) has direct evidence for it, and S. pombe wss1 deletion mutants are sensitive to formaldehyde and acetaldehyde, two DPC-inducing agents.
Reason: Wss1 does the work of this process, because it proteolyses the protein component of the crosslink. The transfer is grounded at the PANTHER subfamily level, and target-organism genetics agree.
We also show the involvement of Wss1-related metalloproteases, Wss1 and Wss2, in acetaldehyde tolerance.
Core Functions
DNA-dependent zinc metalloendopeptidase of the Wss1 subfamily that proteolyses proteins covalently trapped on DNA in the nucleus, removing DNA-protein crosslinks so that downstream repair can proceed.
Q: Does Wss1 associate with any nuclear membrane or membrane-bound complex, or is its nuclear signal restricted to soluble chromatin-associated pools?
Q: Are fission-yeast Wss1 (PTHR46622) and Wss2/Wss1b (PTHR47795) redundant for DNA-protein crosslink repair, or do they handle distinct lesion classes (e.g. Top1 cleavage complexes vs aldehyde-induced crosslinks)?
Suggested Experiments
Experiment: Purify recombinant Wss1 and its catalytic mutant (E97Q) and test DNA-dependent cleavage of a model DNA-bound substrate (e.g. histone H1 or Top1 cleavage complex). Test wss1-E97Q for formaldehyde and camptothecin sensitivity, alone and combined with wss2 and tdp1 deletions.
External Prediction Reviews
These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.
ProtNLM2 emits one GO prediction for fission-yeast Wss1, the broad cellular component membrane (GO:0016020). It is scored UNC. Wss1 is an experimentally nuclear WLM-family DNA-dependent metalloprotease acting in DNA-protein crosslink repair, and neither the fission-yeast data nor the budding-yeast ortholog's localization (a focus near the nuclear membrane; vacuolar under genotoxic stress) establishes membrane residence, while the absence of a transmembrane segment does not exclude peripheral association.
Review rationale: The prediction is absent from GOA, which carries only nucleus (GO:0005634) for the cellular-component aspect, and the gene review accepts nucleus as the sole supported location. The reviewed UniProt record places Wss1 in the nucleus from experimental evidence, and the ProtNLM2 source hydrates the membrane claim from KW-0539 (Nucleus), which is not a membrane observation. The closest relative evidence, from budding-yeast Wss1 in the same PANTHER subfamily, is a GFP focus near the nuclear membrane and vacuolar localization upon genotoxic stress; proximity to the nuclear envelope and relocation to the vacuole do not demonstrate membrane association. Because a soluble protease lacking transmembrane helices could still associate peripherally with membranes, the claim is not refuted. Membrane fractionation, nuclear-envelope colocalization or a defined membrane-associated partner complex for Wss1 is missing.