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Logo of bmcmicrBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Microbiology
 
BMC Microbiol. 2012; 12: 6.
Published online Jan 13, 2012. doi:  10.1186/1471-2180-12-6
PMCID: PMC3398298
Characterization of the biotin uptake system encoded by the biotin-inducible bioYMN operon of Corynebacterium glutamicum
Jens Schneider,1 Petra Peters-Wendisch,corresponding author1,3 K Corinna Stansen,1 Susanne Götker,1 Stanislav Maximow,2 Reinhard Krämer,2 and Volker F Wendisch1
1Genetics of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, Bielefeld, Germany
2Institute for Biochemistry, Cologne University, Cologne, Germany
3Genetics of Prokaryotes, Bielefeld University, P.O. Box 100131, 33501 Bielefeld, Germany
corresponding authorCorresponding author.
Jens Schneider: jensschn/at/cebitec.uni-bielefeld.de; Petra Peters-Wendisch: petra.peters-wendisch/at/uni-bielefeld.de; K Corinna Stansen: K.C.Stansen/at/web.de; Susanne Götker: sgoetker/at/cebitec.uni-bielefeld.de; Stanislav Maximow: stmax83/at/googlemail.com; Reinhard Krämer: r.kraemer/at/uni-koeln.de; Volker F Wendisch: volker.wendisch/at/uni-bielefeld.de
Received November 16, 2011; Accepted January 13, 2012.
Abstract
Background
The amino acid-producing Gram-positive Corynebacterium glutamicum is auxotrophic for biotin although biotin ring assembly starting from the precursor pimeloyl-CoA is still functional. It possesses AccBC, the α-subunit of the acyl-carboxylases involved in fatty acid and mycolic acid synthesis, and pyruvate carboxylase as the only biotin-containing proteins. Comparative genome analyses suggested that the putative transport system BioYMN encoded by cg2147, cg2148 and cg2149 might be involved in biotin uptake by C. glutamicum.
Results
By comparison of global gene expression patterns of cells grown with limiting or excess supply of biotin or with dethiobiotin as supplement replacing biotin revealed that expression of genes coding for enzymes of biotin ring assembly and for the putative uptake system was regulated according to biotin availability. RT-PCR and 5'-RACE experiments demonstrated that the genes bioY, bioM, and bioN are transcribed from one promoter as a single transcript. Biochemical analyses revealed that BioYMN catalyzes the effective uptake of biotin with a concentration of 60 nM biotin supporting a half-maximal transport rate. Maximal biotin uptake rates were at least five fold higher in biotin-limited cells as compared to cells grown with excess biotin. Overexpression of bioYMN led to an at least 50 fold higher biotin uptake rate as compared to the empty vector control. Overproduction of BioYMN alleviated biotin limitation and interfered with triggering L-glutamate production by biotin limitation.
Conclusions
The operon bioYMN from C. glutamicum was shown to be induced by biotin limitation. Transport assays with radio-labeled biotin revealed that BioYMN functions as a biotin uptake system. Overexpression of bioYMN affected L-glutamate production triggered by biotin limitation.
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