The Structure of ll-Diaminopimelate Aminotransferase from Chlamydia trachomatis: Implications for Its Broad Substrate Specificity

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• 作者：Nobuhiko Watanabe¹ ; Matthew D. Clay² ; Marco J. van Belkum¹ ; Chenguang Fan³ ; John C. Vederas³ ; Michael N.G. James¹ ; ^{michael.james@ualberta.ca"" rel=""nofollow}
• 关键词：lysine biosynthesis ; aminotransferase ; Chlamydia ; diaminopimelate ; pyridoxal 5′ ; -phosphate
• 刊名：Journal of Molecular Biology
• 出版年：2011
• 出版时间：19 August 2011
• 年：2011
• 卷：411
• 期：3
• 页码：649-660
• 全文大小：2424 K

文摘

We have previously reported the structures of the native holo and substrate-bound forms of ll-diaminopimelate aminotransferase from Arabidopsis thaliana (AtDAP-AT). Here, we report the crystal and molecular structures of the ll-diaminopimelate aminotransferase from Chlamydia trachomatis (CtDAP-AT) in the apo-form and the pyridoxal-5′-phosphate-bound form. The molecular structure of CtDAP-AT shows that its overall fold is essentially identical with that of AtDAP-AT except that CtDAP-AT adopts an ȁc;open” conformation as opposed to the ȁc;closed” conformation of AtDAP-AT. Although AtDAP-AT and CtDAP-AT are approximately 40 % identical in their primary sequence, they have major differences in their substrate specificities; AtDAP-AT is highly specific for LL-DAP, whereas CtDAP-AT accepts a wider range of substrates. Since all of the residues involved in substrate recognition are highly conserved between AtDAP-AT and CtDAP-AT, we propose that differences in flexibility of the loops lining the active-site region between the two enzymes likely account for the differences in substrate specificity.