Expression of a novel gene, gluP, is essential for normal Bacillus subtilis cell division and contributes to glucose export
1 Department of Microbiology, Institute for Microbiology, Biochemistry and Genetics University of Erlangen-Nuremberg, Staudstrasse 5, 91058 Erlangen, and Department of Biology, University of Konstanz, Universitaetstrasse 1, 78457 Konstanz, Germany
2 Centre for Cancer Therapeutics, Ottawa Regional Cancer Centre, and Faculty of Medicine, University of Ottawa, 503 Smyth Rd., Ottawa, ON, K1H 1C4, Canada
3 Division of Molecular and Cellular Biology, The Mochtar Riady Center for Nanotechnology and Bioengineering, PO BOX 326 TNG 15001, Tangerang, Banten, Indonesia
BMC Microbiology 2004, 4:13 doi:10.1186/1471-2180-4-13Published: 30 March 2004
The Bacillus subtilis glucokinase operon was predicted to be comprised of the genes, yqgP (now named gluP), yqgQ, and glcK. We have previously established a role for glcK in glucose metabolism. In the absence of enzymes that phosphorylate glucose, such as GlcK and/or enzyme IIGlc, accumulated cytoplasmic glucose can be transported out of the cell. Genes within the glucokinase operon were not previously known to play a role in glucose transport. Here we describe the expression of gluP and its function in glucose transport.
We found that transcription of the glucokinase operon was regulated, putatively, by two promoters: σA and σH. Putative σA and σH-recognition sites were located upstream of and within gluP, respectively. Transcriptional glucokinase operon – lacZ fusions and Northern blotting were used to analyze the expression of gluP. GluP was predicted to be an integral membrane protein. Moreover, the prediction of GluP structure revealed interesting signatures: a rhomboid domain and two tetracopeptide repeat (TPR) motifs. Microscopic analysis showed that GluP minus cells were unable to divide completely, resulting in a filamentous phenotype. The cells were grown in either rich or minimal medium. We found GluP may be involved in glucose transport. [14C]-glucose uptake by the GluP minus strain was slightly less than in the wild type. On the other hand, trehalose-derived glucose in the growth medium of the GluP minus strain was detected in very low amounts. Experimental controls comprised of single or multiple genes mutations within the glucose transporting phosphotransferase system.
gluP seems to be regulated only by a putative σA-dependent promoter. The glucose uptake and export assays suggest that GluP is important for glucose export and may act as an exporter. This also supports the role of the glucokinase operon in glucose utilization.