title: Rho and RNase play a central role in FMN riboswitch regulation in Corynebacterium glutamicum.
abstract: Riboswitches are RNA elements that regulate gene expression in response to their ligand. Although these regulations are thought to be performed without any aid of other factors, recent studies suggested the participation of protein factors such as transcriptional termination factor Rho and RNase in some riboswitch regulations. However, to what extent these protein factors contribute to the regulation was unclear. Here, we studied the regulatory mechanism of the flavin mononucleotide (FMN) riboswitch of Corynebacterium glutamicum which controls the expression of downstream ribM gene. Our results showed that this riboswitch downregulates both ribM mRNA and RibM protein levels in FMN-rich cells. Analysis of mRNA stability and chromatin immunoprecipitation-real-time PCR analysis targeting RNA polymerase suggested the involvement of the mRNA degradation and premature transcriptional termination in this regulation, respectively. Simultaneous disruption of RNase E/G and Rho function completely abolished the regulation at the mRNA level. Also, the regulation at the protein level was largely diminished. However, some FMN-dependent regulation at the protein level remained, suggesting the presence of other minor regulatory mechanisms. Altogether, we demonstrated for the first time that two protein factors, Rho and RNase E/G, play a central role in the riboswitch-mediated gene expression control.
authors.affiliation: Research Institute of Innovative Technology for the Earth, 9-2 Kizugawadai, Kizugawa, Kyoto 619-0292, Japan.
authors.forename: Norihiko
authors.initials: N
authors.lastname: Takemoto
authors.affiliation: Research Institute of Innovative Technology for the Earth, 9-2 Kizugawadai, Kizugawa, Kyoto 619-0292, Japan.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Research Institute of Innovative Technology for the Earth, 9-2 Kizugawadai, Kizugawa, Kyoto 619-0292, Japan Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan mmg-lab@rite.or.jp.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Inui
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D005486:Flavin Mononucleotide / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012234:Rho Factor / Q000037:antagonists & inhibitors / Q000502:physiology*; D058928:Riboswitch; D061805:Transcription Elongation, Genetic; D061806:Transcription Termination, Genetic
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D012234:Rho Factor; D058928:Riboswitch; D005486:Flavin Mononucleotide; D004722:Endoribonucleases; C022537:ribonuclease E