ACE1 (G4MVZ2, MGG_12447) — Pyricularia oryzae 70-15 — curation notes

Sources

• UniProt G4MVZ2 (Swiss-Prot), deep research ACE1-deep-research-falcon.md.
• Cached full text: PMID:15319478 (Boehnert 2004), PMID:17142568 (Fudal 2007), PMID:29142718 (Song 2015).
• Abstract only: PMID:12838393 (Pi33 mapping), PMID:18433432 (cluster), PMID:31644300 (CYP1/CYP3).
• Not cached / not used for quotes: Zhang 2021 (Chem Eur J; ORFZ/ORF3 cross-complementation), Lambou 2024 (PLoS Pathog; BIP1 regulation) — summarized only via the deep-research file.

Identity and architecture

• Hybrid iterative highly reducing PKS fused to one NRPS module, 4034-4035 aa.
  PMID:29142718
  UniProt: "ACE1 has the following architecture: KS-AT-DH-MT-KR-PCP-C-A-T-R."
• Embedded ER domain is inactive (ER0); trans-ER RAP1 supplies enoyl reduction.
  PMID:29142718

Catalysis (heterologous expression)

• ACE1 alone in A. oryzae / M. oryzae: heptaketide pyrone (magnaporthepyrone) and diols.
  PMID:29142718
• ACE1 + RAP1: tyrosine-containing nonaketide amide 8 (cytochalasan-like backbone).
  PMID:29142718
  PMID:29142718
• None of the isolated products (6, 7, 8) is the Pi33 avirulence signal; native product unknown.

In planta

• KS active-site Cys183Ala abolishes avirulence on Pi33 rice although the protein is expressed and localized: enzymatic activity, not the protein, is recognized.
  PMID:15319478
• Ace1-GFP (functional) is cytoplasmic in appressoria, not secreted.
  PMID:15319478
• Expression restricted to appressoria at the onset of penetration.
  PMID:17142568
• 15-gene infection-specific cluster; SYN2, RAP2 dispensable for avirulence (PMID:18433432 abstract).

Annotation decisions (summary)

• Fatty acid synthase activity / fatty acid biosynthetic process: IEA family transfers from the shared KS/AT fold; ACE1 is a PKS-NRPS making a polyketide-amino acid hybrid, not fatty acids -> MODIFY to polyketide synthase activity (GO:0016218) / polyketide biosynthetic process (GO:0030639).
• Condensation-domain "catalytic activity" -> MODIFY to non-ribosomal peptide synthetase activity (GO:1904091). Comparator: fungal PKS-NRPS hybrids iccA (A0A482N9V7) and iliA (P0DO30) carry both GO:0016218 and GO:1904091 by IDA in QuickGO, so assigning both to ACE1 follows existing practice.
• No avirulence/host-interaction process term added: ACE1 is an intracellular biosynthetic enzyme; the recognized entity is an unidentified metabolite, and the plant-side response is performed by Pi33 rice. Effector terms (e.g. GO:0080185) would require the gene product (or a defined product) to act on the host. Raised as a suggested question.