Detail GNAT-Like Strategy for Polyketide Chain Initiation   Oleh:  Liangcai, Gu ; Geders, Todd W. ; Bo, Wang ; Gerwick, William H. ; Håkansson, Kristina ; Smith, Janet L. ; Sherman, David H. Jenis: Article from Bulletin/Magazine Dalam koleksi: SCIENCE (keterangan: ada di Proquest) vol. 318 no. 5852 (Nov. 2007), page 970. Ketersediaan Perpustakaan FK Nomor Panggil: S01.K.2007.09 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada     Lihat Detail Induk Isi artikel An unexpected biochemical strategy for chain initiation is described for the loading module of the polyketide synthase of curacin A, an anticancer lead derived from the marine cyanobacterium Lyngbya majuscula. A central GCN5-related N-acetyltransferase (GNAT) domain bears bifunctional decarboxylase/S-acetyltransferase activity, both unprecedented for the GNAT superfamily. A CurA loading tridomain, consisting of an adaptor domain, the GNAT domain, and an acyl carrier protein, was assessed biochemically, revealing that a domain showing homology to GNAT (GNATL) catalyzes (i) decarboxylation of malonyl-coenzyme A (malonyl-CoA) to acetyl-CoA and (ii) direct S-acetyl transfer from acetyl-CoA to load an adjacent acyl carrier protein domain (ACPL). Moreover, the N-terminal adapter domain was shown to facilitate acetyl-group transfer. Crystal structures of GNATL were solved at 1.95 angstroms (ligand-free form) and 2.75 angstroms (acyl-CoA complex), showing distinct substrate tunnels for acyl-CoA and holo-ACPL binding. Modeling and site-directed mutagenesis experiments demonstrated that histidine-389 and threonine-355, at the convergence of the CoA and ACP tunnels, participate in malonyl-CoA decarboxylation but not in acetyl-group transfer. Decarboxylation precedes acetyl-group transfer, leading to acetyl-ACPL as the key curacin A starter unit. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Kembali

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