title: Characterization of the mannitol catabolic operon of Corynebacterium glutamicum.
abstract: Corynebacterium glutamicum encodes a mannitol catabolic operon, which comprises three genes: the DeoR-type repressor coding gene mtlR (sucR), an MFS transporter gene (mtlT), and a mannitol 2-dehydrogenase gene (mtlD). The mtlR gene is located upstream of the mtlTD genes in the opposite orientation. In spite of this, wild-type C. glutamicum lacks the ability to utilize mannitol. This wild-type phenotype results from the genetic regulation of the genes coding for mannitol transport and catalytic proteins mediated by the autoregulated MtlR protein since mtlR mutants grow on mannitol as the sole carbon source. MtlR binds to sites near the mtlR (two sites) and mtlTD promoters (one site downstream of the promoter), with the consensus sequence 5'-TCTAACA-3' being required for its binding. The newly discovered operon comprises the three basic functional elements required for mannitol utilization: regulation, transport, and metabolism to fructose, further processed to the common intermediate of glycolysis fructose-6-phosphate. When relieved from MtlR repression, C. glutamicum, which lacks a functional fructokinase, excretes the fructose derived from mannitol and imports it by the fructose-specific PTS. In order to use mannitol from seaweed biomass hydrolysates as a carbon source for the production of useful commodity chemicals and materials, an overexpression system using the tac promoter was developed. For congruence with the operon, we propose to rename sucR as the mtlR gene.
authors.affiliation: Molecular Microbiology and Biotechnology Group, Research Institute of Innovative Technology for the Earth (RITE), 9-2 Kizugawadai, Kizugawa, Kyoto 619-0292, Japan.
authors.forename: Xue
authors.initials: X
authors.lastname: Peng
authors.forename: Naoko
authors.initials: N
authors.lastname: Okai
authors.forename: Alain A
authors.initials: AA
authors.lastname: Vertès
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Inatomi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Inui
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yukawa
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D048230:Corynebacterium glutamicum / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008353:Mannitol / Q000378:metabolism*; D008969:Molecular Sequence Data; D009876:Operon; D011401:Promoter Regions, Genetic
chemical_list: D001426:Bacterial Proteins; D008353:Mannitol