2008 Rustbelt RNA Meeting
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Poster number 63 submitted by Theresa Rogers

Stationary phase expression and aminoacylation of a tRNA-like small RNA in Bacillus cereus

Theresa E. Rogers (Department of Microbiology, The Ohio State University), Sandro Ataide (Department of Microbiology, The Ohio State University), Michael Ibba (Department of Microbiology, The Ohio State University)

Abstract:
Genomic-scale analyses have revealed numerous functional duplications within the canonical translation machinery, such as the occurrence of unrelated class I and II lysyl-tRNA synthetases (LysRS), which can act in concert to aminoacylate non-canonical tRNAs. To date, LysRS1 and LysRS2 have only been found together in the Methanosarcinaceae in the archaea and in a few Bacilli among the bacteria, including Bacillus cereus. The role the two LysRSs play in B. cereus was investigated. It was found that the class I and II LysRSs could act together to aminoacylate a small RNA of unknown function (tRNAOther). tRNAOther is encoded within a pathogenicity island together with several putative virulence factors. In vivo analyses revealed that LysRS1 and tRNAOther were mainly produced during stationary phase. To investigate the role of tRNAOther in B. cereus, we deleted the corresponding gene and screened for changes in growth phenotype compared to wild-type. Deletion of tRNAOther was not deleterious, and growth in rich media and ability to sporulate were virtually unchanged. Changes were observed in stationary phase such as de-regulation of the production of a bacteriocin-like inhibitory susbstance, and increased responsiveness to various germinants. Extensive screening for growth phenotype changes (~1900 conditions) was carried out by performing phenotypic microarray analyses (BIOLOG, Inc.). These studies revealed significant changes; B. cereus ÄtRNAOther gained resistance to several antibiotics (eg., erythromycin and oleandomycin), but also acquired sensitivity to a number of compounds including antibiotics, cationic detergents and positively charged ionophores. tRNAOther could not be detected in polysomes isolated from cells collected during exponential or early stationary phases, indicating a function beyond translation.

Keywords: Aminoacyl-tRNA synthetases