Staphylococcus Research Today is a free monthly online journal that collates and summarizes the latest research about Staphylococcus, including details on mrsa, hospitals, infection, antibiotic resistance, superbugs.

Ammonia channel couples glutaminase with transamidase reactions in GatCAB.

Nakamura A, Yao M, Chimnaronk S, Sakai N, Tanaka I

Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan.

The formation of glutaminyl transfer RNA (Gln-tRNA(Gln)) differs among the three domains of life. Most bacteria employ an indirect pathway to produce Gln-tRNA(Gln) by a heterotrimeric glutamine amidotransferase CAB (GatCAB) that acts on the misacylated Glu-tRNA(Gln). Here, we describe a series of crystal structures of intact GatCAB from Staphylococcus aureus in the apo form and in the complexes with glutamine, asparagine, Mn2+, and adenosine triphosphate analog. Two identified catalytic centers for the glutaminase and transamidase reactions are markedly distant but connected by a hydrophilic ammonia channel 30 A in length. Further, we show that the first U-A base pair in the acceptor stem and the D loop of tRNA(Gln) serve as identity elements essential for discrimination by GatCAB and propose a complete model for the overall concerted reactions to synthesize Gln-tRNA(Gln).

Published 30 June 2006 in Science, 312(5782): 1954-8.
Full-text of this article is available online (may require subscription).

© 2004-2008 Staphylococcus Research Today. All Rights Reserved.