title: The physiological role of riboflavin transporter and involvement of FMN-riboswitch in its gene expression in Corynebacterium glutamicum.
abstract: Riboflavin is a precursor of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which work as cofactors of numerous enzymes. Understanding the supply system of these cofactors in bacteria, particularly those used for industrial production of value added chemicals, is important given the pivotal role the cofactors play in substrate metabolism. In this work, we examined the effect of disruption of riboflavin utilization genes on cell growth, cytoplasmic flavin levels, and expression of riboflavin transporter in Corynebacterium glutamicum. Disruption of the ribA gene that encodes bifunctional GTP cyclohydrolase II/3,4-dihydroxy-2-butanone 4-phosphate synthase in C. glutamicum suppressed growth in the absence of supplemental riboflavin. The growth was fully recovered upon supplementation with 1 μM riboflavin, albeit at reduced intracellular concentrations of FMN and FAD during the log phase. Concomitant disruption of the ribA and ribM gene that encodes a riboflavin transporter exacerbated supplemental riboflavin requirement from 1 μM to 50 μM. RibM expression in FMN-rich cells was about 100-fold lower than that in FMN-limited cells. Mutations in putative FMN-riboswitch present immediately upstream of the ribM gene abolished the FMN response. This 5'UTR sequence of ribM constitutes a functional FMN-riboswitch in C. glutamicum.
authors: Research Institute of Innovative Technology for the Earth, 9-2 Kizugawadai, Kizugawa, Kyoto, 619-0292, Japan.
authors: Norihiko
authors: N
authors: Takemoto
authors: Yuya
authors: Y
authors: Tanaka
authors: Masayuki
authors: M
authors: Inui
authors: Hideaki
authors: H
authors: Yukawa
mesh_terms: D020121:5' Untranslated Regions; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D005486:Flavin Mononucleotide / Q000378:metabolism*; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D055786:Gene Knockout Techniques; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D012256:Riboflavin / Q000378:metabolism*; D058928:Riboswitch
chemical_list: D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D003470:Culture Media; D026901:Membrane Transport Proteins; D058928:Riboswitch; D005486:Flavin Mononucleotide; D012256:Riboflavin