分类: 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间: 2016-05-12
摘要: The biotin biosynthesis pathway is an attractive target for development of novel drugs against mycobacterial pathogens, however there are as yet no suitable inhibitors that target this pathway in mycobacteria. 7-Keto-8-aminopelargonic acid synthase (KAPA synthase, BioF) is the enzyme which catalyzes the first committed step of the biotin synthesis pathway, but both its structure and function in mycobacteria remain unresolved. Here we present the crystal structure of Mycobacterium smegmatis BioF (MsBioF). The structure reveals an incomplete dimer, and the active site organization is similar to, but distinct from Escherichia coli 8-amino-7-oxononanoate synthase (EcAONS), the E. coli homologue of BioF. To investigate the influence of structural characteristics on the function of MsBioF, we deleted bioF in M. smegmatis and confirmed that BioF is required for growth in the absence of exogenous biotin. Based on structural and mutagenesis studies, we confirmed that pyridoxal 5'-phosphate (PLP) binding site residues His129, Lys235 and His200 are essential for MsBioF activity in vivo and residue Glul 71 plays an important, but not essential role in MsBioF activity. The N-terminus (residues 1-37) is also essential for MsBioF activity in vivo. The structure and function of MsBioF reported here provides further insights for developing new anti-tuberculosis inhibitors aimed at the biotin synthesis pathway. (C) 2014 Elsevier Ltd. All rights reserved.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-12
摘要: Rv0880 from the pathogen Mycobacterium tuberculosis is classified as a MarR family protein in the Pfam database. It consists of 143 amino acids and has an isoelectric point of 10.9. Crystals of Rv0880 belonged to space group P1, with unit-cell parameters a = 54.97, b = 69.60, c = 70.32 angstrom, alpha = 103.71, beta = 111.06, gamma = 105.83 degrees. The structure of the MarR family transcription regulator Rv0880 was solved at a resolution of 2.0 angstrom with an R-cryst and R-free of 21.2 and 24.9%, respectively. The dimeric structure resembles that of other MarR proteins, with each subunit comprising a winged helix-turn-helix domain connected to an alpha-helical dimerization domain.