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Discovery of an asymmetric ATPase with two catalytic centers that are separately activated by two different misacylated‐tRNAs (751.2)
Author(s) -
Hendrickson Tamara
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.751.2
Subject(s) - transfer rna , aminoacylation , biochemistry , amino acid , translation (biology) , aminoacyl trna synthetase , enzyme , glutamine amidotransferase , biology , atpase , chemistry , rna , glutamine , messenger rna , gene
A majority of microorganisms lack a complete set of aminoacyl‐tRNA synthetases but still utilize the twenty standard amino acids in their proteomes. The pathogenic bacterium Helicobacter pylori is missing both the glutaminyl‐ and asparaginyl‐tRNA synthetases and instead uses indirect tRNA aminoacylation to generate Gln‐tRNA Gln and Asn‐tRNA Asn . This process proceeds via misacylation of these tRNAs to produce Glu‐tRNA Gln and Asp‐tRNA Asn , followed by transamidative conversion of the two amino acid side chains to produce Gln‐tRNA Gln and Asn‐tRNA Asn . Both misacylated tRNA conversions rely on an amidotransferase called GatCAB. We have identified a new enzyme from H. pylori that induces the formation of a macromolecular complex that also contains this organism’s misacylating aspartyl‐tRNA synthetase (ND‐AspRS) and GatCAB. This enzyme contains two different ATPase active sites, one based on a classic P‐loop ATPase domain and the second based on an [[Unsupported Character ‐ Symbol Font □]]‐adenosine nucleotide hydrolase (AANH) domain. Remarkably, the P‐Loop ATPase is activated by binding of Asp‐tRNA Asn , whereas the AANH ATPase is activated by Glu‐tRNA Gln . These ATPase activities modulate GatCAB activity to drive conversion of both misacylated tRNAs into their cognate products. The asymmetric nature of this enzyme and its activation by different misacylated tRNAs make it an unusual new participant in tRNA aminoacylation and protein translation.