An essential GTPase, der, containing double GTP-binding domains from Escherichia coli and Thermotoga maritima.
A gene encoding a putative GTPase containing two tandemly repeated GTP-binding domains from a hyperthermophilic bacterium, Thermotoga maritima, was cloned and expressed in Escherichia coli. The gene (TM1446) termed der is highly conserved in Eubacteria including E. coli. The purified der product (Tm-Der) has GTPase activity but no ATPase activity. GTP, GDP, and dGTP but not GMP, ATP, CTP, and UTP compete for GTP binding to Tm-Der. An optimal condition for the GTPase assay was determined to be pH 7.5 in 400 mm KCl and 5 mm MgCl(2) at 70 degrees C, where K(m), V(max), and k(cat) values were determined to be 110 microm, 3.46 microm/min, and 0.87 min(-1), respectively. A der deletion strain of E. coli was constructed by replacing the der gene (originally annotated yfgK) with a kanamycin resistance gene. The deletion strain was found to form colonies only if the cells harbored a plasmid containing der, indicating that der is essential for E. coli growth.
Hwang
J
J
Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
Inouye
M
M
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D004926:Escherichia coli / Q000737:chemistry*; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D008969:Molecular Sequence Data; D020124:Thermotoga maritima / Q000737:chemistry*
D001426:Bacterial Proteins; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases