Exposure of Bacillus subtilis to mercury induces accumulation of shorter tRNA Cys species.

Metallomics : integrated biometal science 2013 Apr

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RNA processing is an essential pathway in the regulation of genetic expression in the cell. In this work, Bacillus subtilis was used to understand the effects of mercury on the mechanism of tRNA metabolism. The CVAAS (cold vapor atomic absorption spectroscopy) method revealed that from the addition of HgCl2 (0.75 μg ml(-1)) during the bacterial exponential phase, ca. 48% of the added mercury was taken up by the cells. This led to an immediate reduction in the rate of cell division. During this response, we observed accumulation of species shorter than mature tRNA(Cys) over a 10 h period. We did not observe this accumulation for another five tRNAs analyzed. tRNA processing is largely dependent on RNase R and PNPase in B. subtilis. Thus, when the exonuclease PNPase was absent, we found that the shorter tRNA(Cys) species increased and mature tRNA(Cys) decreased after mercury addition, but this proportion changed during the time analyzed. However, in the absence of RNase R and PNPase the accumulation of the shorter tRNA(Cys) was more pronounced and the mature form was not recovered. In the single rnr mutant strain the shorter tRNA(Cys) was not observed. All together, we provide in vivo evidence that PNPase and RNase R are indispensable in controlling tRNA(Cys) quality in the presence of mercury.

Citation

Andrés Cruz Hernández, Emmanuel Sánchez Millan, Sergio de Jesús Romero Gómez, José Antonio Cervantes Chávez, Rocio Garcia Martínez, Xóchitl Pastrana Martínez, Jackeline Lizzeta Arvizu Gómez, George H Jones, Juan Campos Guillén. Exposure of Bacillus subtilis to mercury induces accumulation of shorter tRNA Cys species. Metallomics : integrated biometal science. 2013 Apr;5(4):398-403