PMID:24963813

Citation	Hobbs, ME, Williams, HJ, Hillerich, B, Almo, SC and Raushel, FM (2014) l-Galactose metabolism in Bacteroides vulgatus from the human gut microbiota. Biochemistry 53:4661-70
Abstract	A previously unknown metabolic pathway for the utilization of l-galactose was discovered in a prevalent gut bacterium, Bacteroides vulgatus. The new pathway consists of three previously uncharacterized enzymes that were found to be responsible for the conversion of l-galactose to d-tagaturonate. Bvu0219 (l-galactose dehydrogenase) was determined to oxidize l-galactose to l-galactono-1,5-lactone with kcat and kcat/Km values of 21 s(-1) and 2.0 × 10(5) M(-1) s(-1), respectively. The kinetic product of Bvu0219 is rapidly converted nonenzymatically to the thermodynamically more stable l-galactono-1,4-lactone. Bvu0220 (l-galactono-1,5-lactonase) hydrolyzes both the kinetic and thermodynamic products of Bvu0219 to l-galactonate. However, l-galactono-1,5-lactone is estimated to be hydrolyzed 300-fold faster than its thermodynamically more stable counterpart, l-galactono-1,4-lactone. In the final step of this pathway, Bvu0222 (l-galactonate dehydrogenase) oxidizes l-galactonate to d-tagaturonate with kcat and kcat/Km values of 0.6 s(-1) and 1.7 × 10(4) M(-1) s(-1), respectively. In the reverse direction, d-tagaturonate is reduced to l-galactonate with values of kcat and kcat/Km of 90 s(-1) and 1.6 × 10(5) M(-1) s(-1), respectively. d-Tagaturonate is subsequently converted to d-glyceraldehyde and pyruvate through enzymes encoded within the degradation pathway for d-glucuronate and d-galacturonate.
Links	PubMed PMC4108180 Online version:10.1021/bi500656m
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Bacteroides/genetics; Bacteroides/metabolism; Galactose/genetics; Galactose/metabolism; Galactose Dehydrogenases/genetics; Galactose Dehydrogenases/metabolism; Humans; Intestines/microbiology; Microbiota
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BACV8:A6KWY2		GO:0016616: oxidoreductase activity, acting on the CH-OH group of donors, NAD or NADP as acceptor	ECO:0000314:		F		Table 1 shows kinetic paramters for the three different enzymes. This protein is Bvu2019. The best activity is seen with L-galactose using NADP as the oxidant. This GO term is broader than required. However the two closest existing GO terms won't be applicable as one is D-galactose with NADP and the other is L-galactose with NAD.	complete CACAO 10205
BACV8:A6KWY2	enables	GO:0016616: oxidoreductase activity, acting on the CH-OH group of donors, NAD or NADP as acceptor	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
BACV8:A6KWY3		GO:0046573: lactonohydrolase activity	ECO:0000314:		F		Table 1 contains kinetic paramters for different substrates. This enzyme is Bvu0220. The substrate that is physiologically relevant is shown to be the 1,5 lactone of glucose (in figure 3-panel B). However, a specific GO term for this reaction does not exist yet and so, the broader GO term for hydrolysis of lactones is used.	complete CACAO 10206
BACV8:A6KWY3	enables	GO:0046573: lactonohydrolase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
BACV8:A6KWY5	enables	GO:0016616: oxidoreductase activity, acting on the CH-OH group of donors, NAD or NADP as acceptor	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
BACV8:A6KWY5		GO:0016616: oxidoreductase activity, acting on the CH-OH group of donors, NAD or NADP as acceptor	ECO:0000314:		F		Kinetic parameters for various substrates are found in table 1. this enzyme is Bvu0222. A specific GO term for galactonate dehydrogenase is unavailable, so the broader GO term for oxidoreductase activity with NAD/NADP is used instead.	complete CACAO 10207

References

See Help:References for how to manage references in GONUTS.