1f7l: Difference between revisions

[[Image:1f7l.jpg|left|200px]]<br /><applet load="1f7l" size="350" color="white" frame="true" align="right" spinBox="true"  

BACKGROUND: Holo-(acyl carrier protein) synthase (AcpS), a member of the phosphopantetheinyl transferase superfamily, plays a crucial role in the functional activation of acyl carrier protein (ACP) in the fatty acid biosynthesis pathway. AcpS catalyzes the attachment of the 4'-phosphopantetheinyl moiety of coenzyme A (CoA) to the sidechain of a conserved serine residue on apo-ACP. RESULTS: We describe here the first crystal structure of a type II ACP from Bacillus subtilis in complex with its activator AcpS at 2.3 A. We also have determined the structures of AcpS alone (at 1.8 A) and AcpS in complex with CoA (at 1.5 A). These structures reveal that AcpS exists as a trimer. A catalytic center is located at each of the solvent-exposed interfaces between AcpS molecules. Site-directed mutagenesis studies confirm the importance of trimer formation in AcpS activity. CONCLUSIONS: The active site in AcpS is only formed when two AcpS molecules dimerize. The addition of a third molecule allows for the formation of two additional active sites and also permits a large hydrophobic surface from each molecule of AcpS to be buried in the trimer. The mutations Ile5--&gt;Arg, Gln113--&gt;Glu and Gln113--&gt;Arg show that AcpS is inactive when unable to form a trimer. The co-crystal structures of AcpS-CoA and AcpS-ACP allow us to propose a catalytic mechanism for this class of 4'-phosphopantetheinyl transferases.

1F7L is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis] with <scene name='pdbligand=CA:'>CA</scene>, <scene name='pdbligand=CL:'>CL</scene> and <scene name='pdbligand=COA:'>COA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Holo-[acyl-carrier-protein]_synthase Holo-[acyl-carrier-protein] synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.8.7 2.7.8.7] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1F7L OCA].  

[[Category: Fritz, C C.]]

[[Category: Parris, K D.]]

[[Category: Somers, W S.]]

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