title: Arabitol metabolism of Corynebacterium glutamicum and its regulation by AtlR.
abstract: Expression profiling of Corynebacterium glutamicum in comparison to a derivative deficient in the transcriptional regulator AtlR (previously known as SucR or MtlR) revealed eight genes showing more than 4-fold higher mRNA levels in the mutant. Four of these genes are located in the direct vicinity of the atlR gene, i.e., xylB, rbtT, mtlD, and sixA, annotated as encoding xylulokinase, the ribitol transporter, mannitol 2-dehydrogenase, and phosphohistidine phosphatase, respectively. Transcriptional analysis indicated that atlR and the four genes are organized as atlR-xylB and rbtT-mtlD-sixA operons. Growth experiments with C. glutamicum and C. glutamicum ΔatlR, ΔxylB, ΔrbtT, ΔmtlD, and ΔsixA derivatives with sugar alcohols revealed that (i) wild-type C. glutamicum grows on D-arabitol but not on other sugar alcohols, (ii) growth in the presence of D-arabitol allows subsequent growth on D-mannitol, (iii) D-arabitol is cometabolized with glucose and preferentially utilized over D-mannitol, (iv) RbtT and XylB are involved in D-arabitol but not in D-mannitol metabolism, (v) MtlD is required for D-arabitol and D-mannitol metabolism, and (vi) SixA is not required for growth on any of the substrates tested. Furthermore, we show that MtlD confers D-arabitol and D-mannitol dehydrogenase activities, that the levels of these and also xylulokinase activities are generally high in the C. glutamicum ΔatlR mutant, whereas in the parental strain, they were high when cells were grown in the presence of D-arabitol and very low when cells were grown in its absence. Our results show that the XylB, RbtT, and MtlD proteins allow the growth of C. glutamicum on D-arabitol and that D-arabitol metabolism is subject to arabitol-dependent derepression by AtlR.
authors.affiliation: Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany.
authors.forename: Tanja
authors.initials: T
authors.lastname: Laslo
authors.forename: Philipp
authors.initials: P
authors.lastname: von Zaluskowski
authors.forename: Christina
authors.initials: C
authors.lastname: Gabris
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Lodd
authors.forename: Christian
authors.initials: C
authors.lastname: Rückert
authors.forename: Petra
authors.initials: P
authors.lastname: Dangel
authors.forename: Jörn
authors.initials: J
authors.lastname: Kalinowski
authors.forename: Marc
authors.initials: M
authors.lastname: Auchter
authors.forename: Gerd
authors.initials: G
authors.lastname: Seibold
authors.forename: Bernhard J
authors.initials: BJ
authors.lastname: Eikmanns
mesh_terms: D048230:Corynebacterium glutamicum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D008353:Mannitol / Q000378:metabolism; D009876:Operon; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013402:Sugar Alcohols / Q000378:metabolism*
chemical_list: D012097:Repressor Proteins; D013402:Sugar Alcohols; D008353:Mannitol; D005947:Glucose; C014999:arabitol