Regulation of the Mannose PTS Operon by the small RNA SgrS

small RNA (sRNA);sugar transport-related sRNA (SgrS);manXYZ;glucose-phosphate stress;Ribonucleic acid (RNA)

Rice, Jennifer

关键词: small RNA (sRNA);    sugar transport-related sRNA (SgrS);    manXYZ;    glucose-phosphate stress;    Ribonucleic acid (RNA);   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/29559/Rice_Jennifer.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

A number of bacterial small RNAs (sRNAs) act as global regulators of stressresponses by controlling expression of multiple genes. The sRNA SgrS is expressedin response to glucose-phosphate stress, a condition associated with disruption ofglycolytic flux and accumulation of sugar-phosphates. SgrS has been shown tostimulate degradation of the ptsG mRNA, encoding the major glucose transporter.This study demonstrates that SgrS regulates the genes encoding the mannose andsecondary glucose transporter, manXYZ. Analysis of manXYZ mRNA stability andtranslation in the presence and absence of SgrS indicate that manXYZ is regulated bySgrS under stress conditions and when SgrS is ectopically expressed. In vitrofootprinting and in vivo mutational analyses showed that SgrS base pairs withmanXYZ within the manX coding sequence to prevent manX translation. Regulationof manX did not require the RNase E degradosome complex, suggesting that theprimary mechanism of regulation is translational. An Escherichia coli ptsG mutantstrain that is manXYZ(+) experiences stress when exposed to the glucose analogs α-methyl glucoside or 2-deoxyglucose. A ptsG manXYZ double mutant is resistant tothe stress, indicating that PTS transporters encoded by both SgrS targets areinvolved in taking up substrates that cause stress. We further demonstrate that SgrSbinds to two sites on the manXYZ mRNA to coordinately down-regulate translationof all the cistrons, a mechanism reminiscent of that used by the eukaryotic miRNA,lin-4 for regulation of the lin-14 mRNA. We tested the hypothesis that regulation ofmanY and manZ is dependent on SgrS:manX base pairing and subsequent manXYZmRNA degradation. Contrary to the hypothesis, we show that SgrS repression ofiiimanY and manZ translation can be decoupled from SgrS-dependent manXYZ mRNAdegradation. Furthermore, SgrS regulates manY translation by a mechanism that isindependent of SgrS:manX mRNA interactions. Instead, translational regulation ofmanY depends on SgrS pairing with sequences in the manX-manY intergenic region,upstream of the manY ribosome binding site. Mutational analysis suggests thatwhile the SgrS-manY interaction is sufficient to stimulate some degradation of themanXYZ mRNA, pairing with both sites is required for maximal degradation of themanXYZ mRNA. Additional SgrS candidate-mRNA targets are also investigated.