Regulation of the transport system for C4-dicarboxylic acids in Bacillus subtilis.
Transport systems for C4-dicarboxylates, such as malate, fumarate and succinate, are poorly understood in Gram-positive bacteria. The whole genome sequence of Bacillus subtilis revealed two genes, ydbE and ydbH, whose deduced products are highly homologous to binding proteins and transporters for C4-dicarboxylates in Gram-negative bacteria. Between ydbE and ydbH, genes ydbF and ydbG encoding a sensor-regulator pair, were located. Inactivation of each one of the ydbEFGH genes caused a deficiency in utilization of fumarate or succinate but not of malate. Expression of ydbH, encoding a putative transporter, was stimulated in a minimal salt medium containing 0-05% yeast extract but repressed by the addition of malate to the medium. Inactivation of the putative sensor-regulator pair or solute-binding protein, ydbFG or ydbE, caused complete loss of ydbH expression. The utilization of fumarate and stimulation of ydbH expression resumed in a ydbE null mutant in which ydbFGH were overproduced. Based on these observations, together with analysis of the sequence similarities of the deduced product, we conclude that YdbH is a C4-dicarboxylate-transport protein and its expression is regulated by a C4-dicarboxylate sensor kinase-regulator pair, YdbF and YdbG. Furthermore, it is suggested that YdbE does not directly participate in transport of C4-dicarboxylates, but plays a sensory role in the ydbF-ydbG two-component system, giving rise to specificity or increased efficiency to the system. Deletion analysis of the promoter region of ydbH revealed that a direct repeat sequence was required for the activation of ydbH expression. A catabolite-responsive element (CRE) was also found in the -10 region of the promoter, suggesting negative regulation by a CRE-binding protein.
Asai
Kei
K
Department of Cell Biology, Graduate school of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan1.
Baik
Sang-Hoon
SH
Department of Cell Biology, Graduate school of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan1.
Kasahara
Yasuhiro
Y
Department of Cell Biology, Graduate school of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan1.
Moriya
Shigeki
S
Department of Cell Biology, Graduate school of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan1.
Ogasawara
Naotake
N
Department of Cell Biology, Graduate school of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan1.
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003470:Culture Media; D003998:Dicarboxylic Acids / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D010957:Plasmids / Q000235:genetics; D013753:Tetracycline Resistance / Q000235:genetics; D014158:Transcription, Genetic; D014169:Transformation, Bacterial
D001426:Bacterial Proteins; D002352:Carrier Proteins; D003470:Culture Media; D003998:Dicarboxylic Acids