Exposure of Bacillus subtilis to mercury induces accumulation of shorter tRNACys species

• Published in: Metallomics Vol. 5; no. 4; pp. 398 - 43
• Main Authors: Cruz Hernández, Andrés, Millan, Emmanuel Sánchez, de Jesús Romero Gómez, Sergio, Antonio Cervantes Chávez, José, Garcia Martínez, Rocio, Pastrana Martínez, Xóchitl, Gómez, Jackeline Lizzeta Arvizu, Jones, George H, Guillén, Juan Campos
• Format: Journal Article
• Language: English
• Published: 27-03-2013
• ISSN: 1756-5901; 1756-591X
• DOI: 10.1039/c3mt20203h

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 HgCl
2
(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.
The effects of mercury on tRNA metabolism are investigated using Northern blotting with wild type, single and double mutants of RNases in
Bacillus subtilis
and CVAAS.