8h5s
Crystal structure of Rv3400 from Mycobacterium tuberculosis
Structural highlights
FunctionPGMB_MYCTU Catalyzes the interconversion of D-glucose 1-phosphate (G1P) and D-glucose 6-phosphate (G6P), forming beta-D-glucose 1,6-(bis)phosphate (beta-G16P) as an intermediate (PubMed:38501428). Does not show phosphatase and pyrophosphatase activity (PubMed:38501428). Is probably one of the key enzymes involved in the metabolism of trehalose, a disaccharide abundantly present in mycobacteria and which plays a crucial role in bacterial physiology and virulence (PubMed:38501428).[1] Publication Abstract from PubMedMycobacterium tuberculosis (Mtb) adapt to various host environments and utilize a variety of sugars and lipids as carbon sources. Among these sugars, maltose and trehalose, also play crucial role in bacterial physiology and virulence. However, some key enzymes involved in trehalose and maltose metabolism in Mtb are not yet known. Here we structurally and functionally characterized a conserved hypothetical gene Rv3400. We determined the crystal structure of Rv3400 at 1.7 A resolution. The crystal structure revealed that Rv3400 adopts Rossmann fold and shares high structural similarity with haloacid dehalogenase family of proteins. Our comparative structural analysis suggested that Rv3400 could perform either phosphatase or pyrophosphatase or beta-phosphoglucomutase (beta-PGM) activity. Using biochemical studies, we further confirmed that Rv3400 performs beta-PGM activity and hence, Rv3400 encodes for beta-PGM in Mtb. Our data also confirm that Mtb beta-PGM is a metal dependent enzyme having broad specificity for divalent metal ions. beta-PGM converts beta-D-glucose-1-phosphate to beta-D-glucose-6-phosphate which is required for the generation of ATP and NADPH through glycolysis and pentose phosphate pathway, respectively. Using site directed mutagenesis followed by biochemical studies, we show that two Asp residues in the highly conserved DxD motif, D29 and D31, are crucial for enzyme activity. While D29A, D31A, D29E, D31E and D29N mutants lost complete activity, D31N mutant retained about 30% activity. This study further helps in understanding the role of beta-PGM in the physiology of Mtb. Biochemical and structural characterization reveals Rv3400 codes for beta-phosphoglucomutase in Mycobacterium tuberculosis.,Singh L, Karthikeyan S, Thakur KG Protein Sci. 2024 Apr;33(4):e4943. doi: 10.1002/pro.4943. PMID:38501428[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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