The stress-responsive dgk gene from Streptococcus mutans encodes a putative undecaprenol kinase activity.
We analyzed a previously constructed stress-sensitive Streptococcus mutans mutant Tn-1 strain resulting from disruption by transposon Tn916 of a gene encoding a protein exhibiting amino acid sequence similarity to the Escherichia coli diacylglycerol kinase. It was confirmed that the mutation led to significantly reduced lipid kinase activity, while expression of the intact gene on a plasmid restored both kinase activity and the wild-type phenotype. Further analysis revealed that the product of the dgk gene in S. mutans predominantly recognizes a lipid substrate other than diacylglycerol, most likely undecaprenol, as demonstrated by its efficient phosphorylation and the resistance of the product of the reaction to saponification. The physiological role of the product of the dgk gene as a putative undecaprenol kinase was further supported by a significantly higher sensitivity of the mutant to bacitracin compared with that of the parental strain.
Lis
Maciej
M
Department of Oral Biology, State University of New York, Buffalo, NY 14214, USA.
Kuramitsu
Howard K
HK
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004251:DNA Transposable Elements; D004075:Diglycerides / Q000378:metabolism; D018869:Heat-Shock Response; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics* / Q000378:metabolism*; D013295:Streptococcus mutans / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D013379:Substrate Specificity; D013729:Terpenes / Q000378:metabolism
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004075:Diglycerides; D013729:Terpenes; C017788:undecaprenol; D017853:Phosphotransferases (Alcohol Group Acceptor); C021454:undecaprenol kinase