Characterization of myo-inositol utilization by Corynebacterium glutamicum: the stimulon, identification of transporters, and influence on L-lysine formation.
Although numerous bacteria possess genes annotated iol in their genomes, there have been very few studies on the possibly associated myo-inositol metabolism and its significance for the cell. We found that Corynebacterium glutamicum utilizes myo-inositol as a carbon and energy source, enabling proliferation with a high maximum rate of 0.35 h-1. Whole-genome DNA microarray analysis revealed that 31 genes respond to myo-inositol utilization, with 21 of them being localized in two clusters of >14 kb. A set of genomic mutations and functional studies yielded the result that some genes in the two clusters are redundant, and only cluster I is necessary for catabolizing the polyol. There are three genes which encode carriers belonging to the major facilitator superfamily and which exhibit a >12-fold increased mRNA level on myo-inositol. As revealed by mutant characterizations, one carrier is not involved in myo-inositol uptake whereas the other two are active and can completely replace each other with apparent Kms for myo-inositol as a substrate of 0.20 mM and 0.45 mM, respectively. Interestingly, upon utilization of myo-inositol, the L-lysine yield is 0.10 mol/mol, as opposed to 0.30 mol/mol, with glucose as the substrate. This is probably not only due to myo-inositol metabolism alone since a mixture of 187 mM glucose and 17 mM myo-inositol, where the polyol only contributes 8% of the total carbon, reduced the L-lysine yield by 29%. Moreover, genome comparisons with other bacteria highlight the core genes required for growth on myo-inositol, whose metabolism is still weakly defined.
Krings
Eva
E
Institute of Biotechnology, Research Centre Juelich, D-52425 Juelich, Germany.
Krumbach
Karin
K
Bathe
Brigitte
B
Kelle
Ralf
R
Wendisch
Volker F
VF
Sahm
Hermann
H
Eggeling
Lothar
L
D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D048230:Corynebacterium glutamicum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007294:Inositol / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000096:biosynthesis*; D046228:Microarray Analysis; D005810:Multigene Family; D009154:Mutation; D012333:RNA, Messenger / Q000235:genetics
D002352:Carrier Proteins; D012333:RNA, Messenger; D007294:Inositol; D008239:Lysine