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|Title:||Ammonia channel couples glutaminase with transamidase reactions in GatCAB|
|Citation:||Science. Vol.312, No.5782 (2006), 1954-1958|
|Abstract:||The formation of glutaminyl transfer RNA (Gln-tRNAGln) differs among the three domains of life. Most bacteria employ an indirect pathway to produce Gln-tRNAGln by a heterotrimeric glutamine amidotransferase CAB (GatCAB) that acts on the misacylated Glu-tRNAGln. 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, Mn 2+, 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 Å in length. Further, we show that the first U-A base pair in the acceptor stem and the D loop of tRNAGln serve as identity elements essential for discrimination by GatCAB and propose a complete model for the overall concerted reactions to synthesize Gln-tRNAGln.|
|Appears in Collections:||Scopus 2006-2010|
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