RNase J is involved in development of drug resistance in mycobacteria

MARTINI MARÍA CARLA; YANG JIAN; ZHAO YANLIN; SHELL SCARLET; HICKS NATHAN; FORTUNE SARAH

Modalidad virtual

Encuentro; X meeting of the Latin American Society of Tuberculosis and other Mycobacteriosis; 2021

Emergence of multi-drug resistance (MDR) in clinical pathogens has become a major health challenge worldwide. While mutations conferring high-level drug resistance in M. tuberculosis (Mtb) are well known, less is known about earlier steps that may precede acquisition of high-level resistance. A recent study reported a set of MDR isolates carrying biased mutations in genes not previously associated with resistance. Among these genes was Rv2752c, encoding ribonuclease RNase J. To investigate the phenotype of Mtb RNase J mutant, we assessed growth inhibition and killing by several drugs. While loss of RNase J alone did not confer high-level resistance to any of the tested drugs, we show that RNase J mutant is more tolerant to a subset of drugs, including the two first-line drugs rifampicin and isoniazid. To study the role of RNase J at a transcriptomic level, we performed RNAseq expression profiling and 5?-end-mapping. We find that loss of RNase J affects the expression levels of a small set of genes. Interestingly, RNase J deletion mutant displayed accumulation of small RNA fragments in some genes, suggesting that RNase J could be involved either in the processing or in the degradation of certain transcripts. Additional experiments to revealed that these fragments are more stable in RNase J mutant. These accumulating fragments have strong predicted secondary structure and high G+C content, supporting a model in which RNase J plays a specialized role in degradation of highly structured RNA molecules that are inefficiently degraded by the core RNA degradation machinery.