Biochemical and Structural Characterization of the Putative Dihydropteroate Synthase Ortholog Rv1207 of Mycobacterium Tuberculosis.Gengenbacher, M., Xu, T., Niyomwattanakit, P., Spraggon, G., Dick, T.
(2008) Fems Microbiol.Lett. 287: 128
- PubMed: 18680522
- DOI: 10.1111/j.1574-6968.2008.01302.x
- PubMed Abstract:
- Crystal Structure of Mycobacterium Tuberculosis 6-Hydroxymethyl-7,8-Dihydropteroate Synthase in Complex with Pterin Monophosphate: New Insight Into the Enzymatic Mechanism and Sulfa-Drug Action
Baca, A.M.,Sirawaraporn, R.,Turley, S.,Sirawaraporn, W.,Hol, W.G.J.
(2000) J.Mol.Biol. 302: 1193
Dihydropteroate synthase (DHPS) is involved in de novo biosynthesis of the essential cofactor folate by catalyzing the condensation of para-aminobenzoic acid (pABA) and 6-hydroxymethyl-7,8-dihydropterin-pyrophosphate (H2PtPP). Mycobacterium tuberculo ...
Dihydropteroate synthase (DHPS) is involved in de novo biosynthesis of the essential cofactor folate by catalyzing the condensation of para-aminobenzoic acid (pABA) and 6-hydroxymethyl-7,8-dihydropterin-pyrophosphate (H2PtPP). Mycobacterium tuberculosis possesses a functional DHPS (MtDHPS, Rv3608c, folP1) and, based on sequence similarities, a putative ortholog (Rv1207, folP2). Here, we demonstrate that Rv1207 shows a low H2PtPP substrate affinity and lacks enzymatic DHPS activity. However, we found dapsone, a structural analog of pABA and clinically used DHPS inhibitor, to weakly bind both proteins. To gain insights into the lack of DHPS activity of Rv1207, its three-dimensional structure was determined at 2.64 A. The overall fold of both, MtDHPS (1EYE) and Rv1207, is highly conserved and conforms to a classical triosephosphate isomerase barrel arrangement. The predicted H2PtPP-binding pocket of Rv1207 is occupied by a histidine side chain, relative to a leucine residue in MtDHPS, consistent with the low affinity for this substrate and the lack of DHPS activity. We conclude that folP2 does not encode a DHPS and therefore cannot act as bypass for folP1. The metabolic function of Rv1207 remains to be defined.
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