Acta Crystallographica Section F

Structural Biology and Crystallization Communications

Volume 64, Part 5 (May 2008)

protein structure communications

 

Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8

B. Bagautdinov, Y. Ukita, M. Miyano and N. Kunishima

Abstract: The -ketoacyl-(acyl carrier protein) synthases (-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 Å resolution. The crystal is orthorhombic, space group P2₁2₁2, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 Å, and contains one homodimer in the asymmetric unit. The subunits adopt the well known ---- thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the `open' conformation of the Phe396 side chain.

PDB reference: 1j3n

Keywords: acyl-carrier protein synthases; homodimers.

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