PA2580 (Q9I0Q6, MdaB) notes
Identity
- UniProt Q9I0Q6, unreviewed, 196 aa; locus PA2580, no gene name in the
entry. Name "NADPH:quinone oxidoreductase MdaB", EC 1.6.5.10, FAD cofactor,
homodimer and cytoplasm are all ARBA-predicted, not curated. Domain: Pfam
PF02525 Flavodoxin_2 (flavodoxin-like fold, 2-188); InterPro IPR052397
NADPH-QR_MdaB; PANTHER PTHR46305:SF3 (NADPH:quinone oxidoreductase MdaB).
No TM segment or signal peptide.
Literature
- Green et al. 2014 (PMID:25085734; abstract only, J Microbiol, not in PMC):
the P. aeruginosa MdaB orthologue (PA2580), purified with four other
quinone reductases, reduces quinones by two-electron transfer
PMID:25085734. Overexpression gave
no H2O2 protection in wild type PMID:25085734, but did in a katA mutant PMID:25085734. No
PA2580 loss-of-function mutant is reported in the abstract.
- Helicobacter pylori MdaB (HP_0630, a PTN002922793 leaf): knockout is
sensitive to O2, H2O2, organic hydroperoxides and paraquat and colonises
mice poorly; the purified enzyme is an NADPH-preferring two-electron quinone
reductase [PMID:14977943 "The mdaB mutant is also more sensitive to H(2)O(2),
organic hydroperoxides, and the superoxide-generating agent paraquat.";
"preferably uses NADPH as an electron donor"]. H. hepaticus MdaB mutant is
likewise oxidative-stress sensitive PMID:17923370.
- E. coli MdaB (P0AEY5, the other MF seed): FAD flavoprotein of the
DT-diaphorase type; a null mutant is not menadione-sensitive, and the
authors favour protection against polyketides PMID:16630630.
Participation test
MdaB itself catalyses the two-electron reduction of quinones, which is the
step that avoids semiquinone-driven ROS production; so a role in the
oxidative stress response is participation, not just a downstream phenotype.
For P. aeruginosa the evidence is weak (gain of function in a katA background
only; no effect in wild type), but for the clade the claim is independently
supported by knockout phenotypes in H. pylori and H. hepaticus MdaB. The E.
coli null result is a caveat, not a contradiction. The PseudoCAP MF row is
right in substance but rests on in vitro enzyme assays, which are IDA, not
IMP.
PseudoCAP IBA-seed assessment
| PTN node |
node term |
n_seeds |
leaf IBAs |
seed annotation (term, evidence, PMID) |
verdict |
rationale |
| PTN002922793 |
GO:0034599 cellular response to oxidative stress |
1 (sole) |
9 (8 taxa) |
GO:0034599, IMP, PMID:25085734 (PseudoCAP) |
SOUND |
Seed is weak (overexpression protects only a katA mutant; no wild-type or loss-of-function phenotype), but MdaB does the protective chemistry itself, and the term holds for the clade on independent knockout evidence from H. pylori HP_0630 (PMID:14977943), a leaf of the node and a better seed. |
| PTN002922793 |
GO:0003955 NAD(P)H dehydrogenase (quinone) activity |
2 |
9 (8 taxa) |
GO:0003955, IMP, PMID:25085734 (PseudoCAP) |
SOUND |
Purified enzyme reduces quinones (two-electron); the abstract supports IDA and describes no mutant, so IMP looks wrong (full text not read). Second seed E. coli MdaB. |
Decisions summary
- ACCEPT: NAD(P)H dehydrogenase (quinone) activity (IBA, IMP), cytosol (IBA).
- MODIFY: catalytic activity (IEA) to GO:0003955; cytoplasm (IEA) to cytosol.
- UNDECIDED: NADPH dehydrogenase (quinone) activity (IEA from EC 1.6.5.10):
the PA enzyme's NADPH preference is not in the abstract.
- KEEP_AS_NON_CORE: cellular response to oxidative stress (IBA, IMP).
- PSEUDOCAP defect: MF row evidence code IMP should be IDA.
Audit 2026-10-29: confidence matched to what was read
PMID:25085734 has no PMC copy; the Springer page is paywalled (abstract
only). The WRONG_EVIDENCE_CODE defect (IMP -> IDA) rests on the abstract
describing no PA2580 mutant, so it is lowered from PROBABLE to SUSPECTED; the
abstract does positively support IDA (in vitro assays of the purified
enzyme). No action changes.