braC (PA1074, P21175) review notes

Periplasmic LIVAT-binding protein of the LIV-I ABC transporter BraCDEFG
(leucine-binding protein family; Pfam Peripla_BP_6; PANTHER PTHR47151).
Reviewed UniProt entry. First gene of the braC-braD-braE-braF-braG operon.

Literature (no deep-research provider available; own reading)

Hoshino and Kose 1989 (abstract only). braC cloned; signal peptide of 26
residues cleaved; protein purified from shock fluid; the braC plasmid restores
LIV-I transport in the braC310 mutant PMID:2509433. 51% identical to E. coli LivJ/LivK.
Johnson et al. 2008 (full text read). Biolog/plate phenotypes of the PA1074
Tn5 mutant: D-Ala C+/-, L-Ala C-, L-Ile C+/-, L-Val N- PMID:18833300. braC is the first gene of the operon, so the insertion may be
polar on braDEFG.
Fernandez et al. 2019 (full text). ITC of purified BraC: nanomolar binding of
the five LIVAT ligands, none of D-Ala or L-Met PMID:31627455; also binds L-homoserine.

PseudoCAP IBA-seed assessment

Other seeds' experimental support queried live in QuickGO on 2026-11-05.

PTN node	node term	n_seeds	leaf IBAs	seed annotation (term, evidence, PMID)	verdict	rationale	other seeds	IBD stands without this seed?
PTN002524712	GO:0015829 valine transport	2	17 (9 taxa)	GO:1903805 L-valine import across plasma membrane, IMP, PMID:18833300 (PseudoCAP)	SOUND	Full text: mutant cannot use L-valine as N source; agrees with direct nanomolar valine binding (PMID:31627455) and LIV-I complementation (PMID:2509433). Node term suits the LivJ/LivK/BraC clade.	E. coli LivJ P0AD96 (EcoCyc IMP, acts_upstream_of_or_within, PMID:323236)	Yes, on LivJ (weakly; IMP upstream-qualified), and BraC's own binding data make the term sound for the clade
PTN002524712	GO:0015818 isoleucine transport	2	17 (9 taxa)	GO:1903806 L-isoleucine import across plasma membrane, IMP, PMID:18833300 (PseudoCAP)	SOUND	Partial growth defect on L-Ile; agrees with direct binding.	E. coli LivJ P0AD96 (EcoCyc IMP PMID:323236)	Yes

No PSEUDOCAP defect on the seed rows and no GO_CENTRAL defect. braG
(reviewed in parallel) sits on a different node (PTN000657089), so braC
shares no node with it.

Other PseudoCAP rows (not seeds)

term	verdict	defect
GO:0042941 D-alanine transmembrane transport (IMP, PMID:18833300)	WRONG	PSEUDOCAP WRONG_TERM, PROBABLE: purified BraC does not bind D-alanine (ITC, PMID:31627455); the weak growth phenotype of a possibly polar insertion does not show BraC-mediated D-Ala transport. This differs from the braG review, which left its D-alanine row UNDECIDED without the ITC paper; the BraC binding data bear on the whole LIV-I system.
GO:0015808 L-alanine transport (IMP)	SOUND	none; MODIFY to GO:1904273 (as on braG)
GO:0015803 branched-chain amino acid transport (IDA, PMID:2509433)	SOUND	none; TOO_GENERAL (entailed by GO:1903805/GO:1903806). The abstract describes genetic complementation, so IMP would fit better than IDA, but not recorded as a defect.