RT Journal Article SR Electronic(1) A1 Baumgardt, Kathrin A1 Melior, Hendrik A1 Madhugiri, Ramakanth A1 Thalmann, Sebastian A1 Schikora, Adam A1 McIntosh, Matthew A1 Becker, Anke A1 Evguenieva-Hackenberg, ElenaYR 2017 T1 RNase E and RNase J are needed for S-adenosylmethionine homeostasis in Sinorhizobium meliloti JF Microbiology, VO 163 IS 4 SP 570 OP 583 DO https://doi.org/10.1099/mic.0.000442 PB Microbiology Society, SN 1465-2080, AB The ribonucleases (RNases) E and J play major roles in E. coli and Bacillus subtilis, respectively, and co-exist in Sinorhizobium meliloti. We analysed S. meliloti 2011 mutants with mini-Tn5 insertions in the corresponding genes rne and rnj and found many overlapping effects. We observed similar changes in mRNA levels, including lower mRNA levels of the motility and chemotaxis related genes flaA, flgB and cheR and higher levels of ndvA (important for glucan export). The acyl-homoserine lactone (AHL) levels were also higher during exponential growth in both RNase mutants, despite no increase in the expression of the sinI AHL synthase gene. Furthermore, several RNAs from both mutants migrated aberrantly in denaturing gels at 300 V but not under stronger denaturing conditions at 1300 V. The similarities between the two mutants could be explained by increased levels of the key methyl donor S-adenosylmethionine (SAM), since this may result in faster AHL synthesis leading to higher AHL accumulation as well as in uncontrolled methylation of macromolecules including RNA, which may strengthen RNA secondary structures. Indeed, we found that in both mutants the N 6-methyladenosine content was increased almost threefold and the SAM level was increased at least sevenfold. Complementation by induced ectopic expression of the respective RNase restored the AHL and SAM levels in each of the mutants. In summary, our data show that both RNase E and RNase J are needed for SAM homeostasis in S. meliloti., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000442