PMID:21984786

Citation	Zhao, J and Binns, AN (2011) Characterization of the mmsAB-araD1 (gguABC) genes of Agrobacterium tumefaciens. J. Bacteriol. 193:6586-96
Abstract	The chvE-gguABC operon plays a critical role in both virulence and sugar utilization through the activities of the periplasmic ChvE protein, which binds to a variety of sugars. The roles of the GguA, GguB, and GguC are not known. While GguA and GguB are homologous to bacterial ABC transporters, earlier genetic analysis indicated that they were not necessary for utilization of sugars as the sole carbon source. To further examine this issue, in-frame deletions were constructed separately for each of the three genes. Our growth analysis clearly indicated that GguA and GguB play a role in sugar utilization and strongly suggests that GguAB constitute an ABC transporter with a wide range of substrates, including L-arabinose, D-fucose, D-galactose, D-glucose, and D-xylose. Site-directed mutagenesis showed that a Walker A motif was vital to the function of GguA. We therefore propose renaming gguAB as mmsAB, for multiple monosaccharide transport. A gguC deletion affected growth only on L-arabinose medium, suggesting that gguC encodes an enzyme specific to L-arabinose metabolism, and this gene was renamed araD1. Results from bioinformatics and experimental analyses indicate that Agrobacterium tumefaciens uses a pathway involving nonphosphorylated intermediates to catabolize L-arabinose via an L-arabinose dehydrogenase, AraA(At), encoded at the Atu1113 locus.
Links	PubMed PMC3232879 Online version:10.1128/JB.05790-11
Keywords	Agrobacterium tumefaciens/genetics; Agrobacterium tumefaciens/metabolism; Arabinose/metabolism; Bacterial Proteins/metabolism; Base Sequence; Gene Expression Regulation, Bacterial; Molecular Sequence Data; Monosaccharide Transport Proteins/genetics; Monosaccharide Transport Proteins/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
AGRT5:Q7CX99		GO:0046373: L-arabinose metabolic process	ECO:0000315:		P		Figure 2 of this paper shows that gguC deletion mutant fails to grow on L-arabinose as a sole C source.	complete
AGRT5:Q7CX97		GO:0005524: ATP binding	ECO:0000315:		F		Fig. 4 shows that a K44A mutation in Ggua significantly slows growth in arabinose. Therefore, it is likely that K44A is a significant residue, and Ggua is most likely an ATP-binding protein since K44 is a highly conserved residue found in ATP-binding proteins.	complete
AGRT5:Q7CX98		GO:0015145: monosaccharide transmembrane transporter activity	ECO:0000315:		F		See Figure 2 that shows gguB functioning with multiple monosaccharides. As the article states within the results section "These data are consistent with the idea that GguA and GguB constitute one transporter which can take up multiple monosaccharides, including l-arabinose, d-fucose, d-galactose, d-glucose, and d-xylose."	complete

References

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