Crystal Structure of Homoserine Transacetylase from Haemophilus influenzae Reveals a New Family of /mg src="http://pubs.acs

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• 作者：I. Ahmad Mirza ; Ishac Nazi ; Magdalena Korczynska ; Gerard D. Wright ; and Albert M. Berghuis
• 刊名：Biochemistry
• 出版年：2005
• 出版时间：December 6, 2005
• 年：2005
• 卷：44
• 期：48
• 页码：15768 - 15773
• 全文大小：665K
• 年卷期：v.44,no.48(December 6, 2005)
• ISSN：1520-4995

文摘

Homoserine transacetylase catalyzes one of the required steps in the biosynthesis of methioninein fungi and several bacteria. We have determined the crystal structure of homoserine transacetylase fromHaemophilus influenzae to a resolution of 1.65 Å. The structure identifies this enzyme to be a memberof the mages/gifchars/alpha.gif" BORDER=0>/mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-hydrolase structural superfamily. The active site of the enzyme is located near the end of adeep tunnel formed by the juxtaposition of two domains and incorporates a catalytic triad involving Ser143,His337, and Asp304. A structural basis is given for the observed double displacement kinetic mechanismof homoserine transacetylase. Furthermore, the properties of the tunnel provide a rationale for howhomoserine transacetylase catalyzes a transferase reaction vs hydrolysis, despite extensive similarity inactive site architecture to hydrolytic enzymes.