Open AccessStructure of 3‐oxoacyl‐(acyl‐carrier protein) synthase II from Thermus thermophilus HB8
Author(s) -
Bagautdinov Bagautdin,
Ukita Yoko,
Miyano Masashi,
Kunishima Naoki
Publication year - 2008
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309108010336
Subject(s) - thermus thermophilus , thiolase , acyl carrier protein , stereochemistry , orthorhombic crystal system , enzyme , atp synthase , biochemistry , chemistry , molecular replacement , active site , crystal structure , biosynthesis , crystallography , escherichia coli , gene , dehydrogenase
The β‐ketoacyl‐(acyl carrier protein) synthases (β‐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 ( Tt KAS II) has been solved by molecular replacement and refined at 2.0 Å resolution. The crystal is orthorhombic, space group P 2 1 2 1 2, 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 α‐β‐α‐β‐α thiolase fold that is common to ACP synthases. The structural and sequence similarities of Tt KAS 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 Tt KAS 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 Tt KAS II is more accessible because of the `open' conformation of the Phe396 side chain.