CMU1 (UMAG_05731, A0A0D1DWQ2) research notes

Sources

• UniProt A0A0D1DWQ2 (Swiss-Prot, experimentally annotated).
• PMID:21976020 (Djamei et al. 2011, Nature) - abstract only in cache.
• PMID:30651637 (Han et al. 2019, Nature) - abstract only in cache.
• PMID:34414650 (Bauters et al. 2021, MPP review) - full text cached; used to verify
  the SA/phenylpropanoid phenotypes from Djamei 2011 that are not in the abstract.
• CMU1-deep-research-falcon.md (Falcon deep research; relies on later reviews for the
  2011 quantitative data).

Findings

• Secreted chorismate mutase (EC 5.4.99.5; signal peptide 1-21; AroQ eukaryotic CM fold).
  Abstract: PMID:21976020
• Uptake into plant cells and spread: PMID:21976020
• Host cytosol + interaction with plant CMs, SA phenotype: PMID:34414650; PMID:34414650
• Mechanistic model (proposed, not flux-traced): PMID:34414650
• Kiwellin ZmKWL1 inhibits Cmu1: PMID:30651637
• UniProt: not allosterically regulated by Trp/Tyr (unlike housekeeping CMs); homodimer;
  heterodimer with ZmCM2; ELR loop 117-140 required for KWL1 binding; R183A/K194A kill activity.

Curation reasoning

• Chorismate mutase activity: the enzyme's own catalysis, purified-protein assays (2011, 2019
  kinetics KM 0.8 mM). Core MF. All three rows accepted.
• GO:0140502 effector-mediated suppression of host SA-mediated innate immune signaling:
  symbiont-side term; Cmu1 performs the catalytic step that drains chorismate, so it does work
  in the process (participation test passes - this is not a substrate case). Strictly the effect
  is on host SA biosynthesis rather than SA signalling; no symbiont-side "suppression of host SA
  biosynthesis" term exists (QuickGO search), so accept and raise as question.
• Aromatic amino acid biosynthetic process (InterPro2GO IEA): the secreted paralogue is not the
  fungal housekeeping Phe/Tyr pathway enzyme; its prephenate feeds the host phenylpropanoid flux.
  Marked over-annotated.
• Chorismate metabolic process (IEA): literally true (it converts chorismate) - kept non-core.
• Locations: extracellular region, host cell cytosol, host apoplast all consistent with
  secretion into the biotrophic interface and translocation; accepted.
• Comparators: PYRO7/PWL2 and PYRO7/slp1 reviews use symbiont-side effector terms
  (GO:0052034 / GO:0140423), consistent with keeping CMU1 on GO:0140502 rather than any
  plant-side defense term.
• No NEW annotations: CM2 heterodimerization and KWL1 binding would only be "protein binding";
  KWL1 inhibition is a host-side function.