Arabidopsis FTSH12 is an AAA-type ATPase component of the Ycf2-FtsHi chloroplast protein-import motor at the inner envelope. It retains a zinc-metalloprotease motif, but disruption of that site preserves its essential import-associated function. Its best-supported role is ATP-dependent preprotein translocation and plastid development; a physiological proteolytic substrate has not been established.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004176 ATP-dependent peptidase activity | IEA GO_REF:0000002 | UNDECIDED | Summary: The FtsH ATPase-protease architecture and zinc motif are retained, but direct physiological ATP-dependent proteolysis by FtsH12 is not established. H769Y supports normal growth and chloroplast import, showing that protease-site function is dispensable for the essential role, not proving that all possible peptidase activity is absent. Supporting Evidence: PMID:30309901 even the FtsH12 zinc binding site is dispensable for its essential function file:ARATH/FTSH12/FTSH12-bioinformatics/RESULTS.md | Binding site: | 769–769 | 1 / 1 | 1 | PMID:33216923 N-terminome analyses further demonstrated normal proteolytic maturation of plastid-imported proteins irrespective of FTSH12 abundance. |
| GO:0004222 metalloendopeptidase activity | IEA GO_REF:0000002 | UNDECIDED | Summary: The complete metalloprotease motif makes activity plausible, but motif conservation alone is insufficient for a confident metalloendopeptidase annotation. Genetic complementation and N-terminomics favor an essential import role and do not identify a cleaved substrate. Supporting Evidence: PMID:30309901 even the FtsH12 zinc binding site is dispensable for its essential function file:ARATH/FTSH12/FTSH12-bioinformatics/RESULTS.md | Binding site: | 769–769 | 1 / 1 | 1 | PMID:33216923 N-terminome analyses further demonstrated normal proteolytic maturation of plastid-imported proteins irrespective of FTSH12 abundance. |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | ACCEPT | Summary: The selected sequence retains the reference ATP-binding region and belongs to the experimentally identified heteromeric AAA import motor. ATP binding is consistent with the conserved motor architecture; the selected terminal difference does not remove the nucleotide-binding module. Supporting Evidence: PMID:30309901 a 2-MD heteromeric AAA-ATPase complex associates with the TIC complex and functions as the import motor, directly interacting with various translocating preproteins file:ARATH/FTSH12/FTSH12-bioinformatics/RESULTS.md | Binding site: | 533–540 | 8 / 8 | 8 | |
| GO:0005737 cytoplasm | IEA GO_REF:0000117 | MODIFY | Summary: Cytoplasm is imprecise for the demonstrated chloroplast inner-envelope compartment. The exact sequence preserves the reference chloroplast targeting peptide and membrane segments, supporting a specific inner-envelope location. Proposed replacements: chloroplast inner membrane Supporting Evidence: PMID:33216923 this unambiguously confirms the localization of FtsH12 in the inner chloroplast envelope file:ARATH/FTSH12/FTSH12-bioinformatics/RESULTS.md | 1–987 | 1–987 | 983 | |
| GO:0006508 proteolysis | IEA GO_REF:0000002 | UNDECIDED | Summary: A direct proteolytic role is not established by the presence of a zinc motif or by altered plastid development after FTSH12 depletion. Normal maturation of imported proteins and zinc-site complementation distinguish the import-motor function from inferred proteolysis. Other substrates or conditions remain possible. Supporting Evidence: PMID:30309901 even the FtsH12 zinc binding site is dispensable for its essential function PMID:33216923 N-terminome analyses further demonstrated normal proteolytic maturation of plastid-imported proteins irrespective of FTSH12 abundance. |
| GO:0016887 ATP hydrolysis activity | IEA GO_REF:0000002 | ACCEPT | Summary: The intact FtsH12 AAA module is part of the ATP-dependent chloroplast import motor. Conserved nucleotide-binding architecture supports ATPase activity in the complex, although an isolated-subunit turnover rate is not assigned. Supporting Evidence: PMID:30309901 a 2-MD heteromeric AAA-ATPase complex associates with the TIC complex and functions as the import motor, directly interacting with various translocating preproteins file:ARATH/FTSH12/FTSH12-bioinformatics/RESULTS.md | Binding site: | 533–540 | 8 / 8 | 8 | |
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