2vvp

Crystal structure of Mycobacterium tuberculosis ribose-5-phosphate isomerase B in complex with its substrates ribose 5-phosphate and ribulose 5-phosphate

spinqualitylabelsall models 2vvp, resolution 1.65Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2vvp is a 5 chain structure with sequence from Mycobacterium tuberculosis H37Rv. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.65Å Ligands: 5RP, R52 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RPIB_MYCTU Has isomerase activity towards D-ribose 5-phosphate, but not towards D-allose 6-phosphate. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Interconversion of D-ribose-5-phosphate (R5P) and D-ribulose-5-phosphate is an important step in the pentose phosphate pathway. Two unrelated enzymes with R5P isomerase activity were first identified in Escherichia coli, RpiA and RpiB. In this organism, the essential 5-carbon sugars were thought to be processed by RpiA, while the primary role of RpiB was suggested to instead be interconversion of the rare 6-carbon sugars D-allose-6-phosphate (All6P) and D-allulose-6-phosphate. In Mycobacterium tuberculosis, where only an RpiB is found, the 5-carbon sugars are believed to be the enzyme's primary substrates. Here, we present kinetic studies examining the All6P isomerase activity of the RpiBs from these two organisms and show that only the E. coli enzyme can catalyze the reaction efficiently. All6P instead acts as an inhibitor of the M. tuberculosis enzyme in its action on R5P. X-ray studies of the M. tuberculosis enzyme co-crystallized with All6P and 5-deoxy-5-phospho-D-ribonohydroxamate (an inhibitor designed to mimic the 6-carbon sugar) and comparison with the E. coli enzyme's structure allowed us to identify differences in the active sites that explain the kinetic results. Two other structures, that of a mutant E. coli RpiB in which histidine 99 was changed to asparagine and that of wild-type M. tuberculosis enzyme, both co-crystallized with the substrate ribose-5-phosphate, shed additional light on the reaction mechanism of RpiBs generally. D-ribose-5-phosphate isomerase B from Escherichia coli is also a functional D-allose-6-phosphate isomerase, while the Mycobacterium tuberculosis enzyme is not.,Roos AK, Mariano S, Kowalinski E, Salmon L, Mowbray SL J Mol Biol. 2008 Oct 10;382(3):667-79. Epub 2008 Jul 9. PMID:18640127 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribose-5-phosphate isomerase 3D structures

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