Reaction: D-xylulose 5-phosphate + [acp] + a [lipoyl-carrier protein]-N6-[(R)-lipoyl]-L-lysine = D-glyceraldehyde 3-phosphate + glycolyl-[acp] + a [lipoyl-carrier protein]-N6-[(R)-dihydrolipoyl]-L-lysine (overall reaction)
(1a) D-xylulose 5-phosphate + a [lipoyl-carrier protein]-N6-[(R)-lipoyl]-L-lysine = D-glyceraldehyde 3-phosphate + a [lipoyl-carrier protein]-N6-[glycolyl-(R)-dihydrolipoyl]-L-lysine
(1b) a [lipoyl-carrier protein]-N6-[glycolyl-(R)-dihydrolipoyl]-L-lysine + [acp] = glycolyl-[acp] + a [lipoyl-carrier protein]-N6-[(R)-dihydrolipoyl]-L-lysine
Other name(s): sclQ1/sclQ2/sclQ3 (gene names); napB/napD (gene names); QncN/QncL (gene names)
Systematic name: D-xylulose 5-phosphate:acyl-carrier protein glycolyltransferase
Comments: This enzyme system produces glycolyl-[acp] units that can be used by non-ribosomal peptide synthases. It catalyses a transketolase-like reaction on ketose phosphates derived from primary metabolism and transfers the resulting glycolyl moiety to a dedicated acyl-carrier protein. During the reaction cycle the glycolyl moiety is transferred first to a thiamine diphosphate cofactor, then to a lipoyl cofactor, and eventually to the acyl-carrier protein. While D-xylulose 5-phosphate is the best substrate, the enzyme can also accept D-fructose 6-phosphate and D-sedheptulose 7-phosphate. During the reaction the lipoyl cofactor is reduced to dihydrolipoyl, which must be oxidized back to lipoyl by an unknown enzyme.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Peng, C., Pu, J.Y., Song, L.Q., Jian, X.H., Tang, M.C. and Tang, G.L. Hijacking a hydroxyethyl unit from a central metabolic ketose into a nonribosomal peptide assembly line. Proc. Natl. Acad. Sci. USA 109 (2012) 8540-8545. [PMID: 22586110]
2. Alberti, F., Leng, D.J., Wilkening, I., Song, L., Tosin, M. and Corre, C. Triggering the expression of a silent gene cluster from genetically intractable bacteria results in scleric acid discovery. Chem. Sci. 10 (2019) 453-463. [PMID: 30746093]