期刊
FEMS MICROBIOLOGY LETTERS
卷 287, 期 1, 页码 128-135出版社
OXFORD UNIV PRESS
DOI: 10.1111/j.1574-6968.2008.01302.x
关键词
Mycobacterium tuberculosis; dihydropteroate synthase; folate; folP1; folP2
类别
资金
- US Department of Energy [DL-AC03-76SF00098]
Dillydropteroate synthase (DHPS) is involved ill 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 angstrom. 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 enode a DHPS and therefore cannot act its bypass for folP1. The metabolic function of Rv1207 remains to be defined.
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