Self-Malonylation Is an Intrinsic Property of a Chemically Synthesized Type II Polyketide Synthase Acyl Carrier Protein

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• 作者：Christopher J. Arthur ; Anna Szafranska ; Simon E. Evans ; Stuart C. Findlow ; Steven G. Burston ; Philip Owen ; Ian Clark-Lewis ; Thomas J. Simpson ; John Crosby ; and Matthew P. Crump
• 刊名：Biochemistry
• 出版年：2005
• 出版时间：November 22, 2005
• 年：2005
• 卷：44
• 期：46
• 页码：15414 - 15421
• 全文大小：182K
• 年卷期：v.44,no.46(November 22, 2005)
• ISSN：1520-4995

文摘

During polyketide biosynthesis, malonyl groups are transferred to the acyl carrier protein (ACP)component of the polyketide synthase (PKS), and it has been shown that a number of type II polyketideACPs undergo rapid self-acylation from malonyl-CoA in the absence of a malonyl-CoA:holo-acyl carrierprotein transacylase (MCAT). More recently, however, the observation of self-malonylation has beenascribed to contamination with Escherichia coli MCAT (FabD) rather than an intrinsic property of theACP. The wild-type apo-ACP from the actinorhodin (act) PKS of Streptomyces coelicolor (syntheticapo-ACP) has therefore been synthesized using solid-state peptide methods and refolded using the GroEL/ES chaperone system from E. coli. Correct folding of the act ACP has been confirmed by circular dichroism(CD) and ¹H NMR. Synthetic apo-ACP was phosphopantetheinylated to 100% by S. coelicolor holo-acylcarrier protein synthase (ACPS), and the resultant holo-ACP underwent self-malonylation in the presenceof malonyl-CoA. No malonylation of negative controls was observed, confirming that the use of ACPSand GroEL/ES did not introduce contamination with E. coli MCAT. This result proves unequivocallythat self-malonylation is an inherent activity of this PKS ACP in vitro.