2REF

Crystal structure of the loading GNATL domain of CurA from Lyngbya majuscula soaked with malonyl-CoA

Summary for 2REF

• Entry DOI: 10.2210/pdb2ref/pdb
• Related: 2ree
• Descriptor: CurA, ACETYL COENZYME *A (3 entities in total)
• Functional Keywords: gnat, curacin, s-acetyltransferase, decarboxylase, polyketide synthase, loading, phosphopantetheine, transferase, lyase
• Biological source: Lyngbya majuscula
• Total number of polymer chains: 2
• Total formula weight: 53446.27

Authors

Geders, T.W.,Smith, J.L. (deposition date: 2007-09-26, release date: 2007-11-20, Last modification date: 2024-04-03)

Primary citation

Gu, L.,Geders, T.W.,Wang, B.,Gerwick, W.H.,Hakansson, K.,Smith, J.L.,Sherman, D.H.
GNAT-like strategy for polyketide chain initiation.
Science, 318:970-974, 2007

PubMed Abstract: 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 (GNAT(L)) 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 (ACP(L)). Moreover, the N-terminal adapter domain was shown to facilitate acetyl-group transfer. Crystal structures of GNAT(L) 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-ACP(L) 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-ACP(L) as the key curacin A starter unit.

PubMed: 17991863
DOI: 10.1126/science.1148790

Experimental method

X-RAY DIFFRACTION (2.75 Å)