title: Reciprocal stimulation of GTP hydrolysis by two directly interacting GTPases.
abstract: The Escherichia coli guanosine triphosphate (GTP)-binding proteins Ffh and FtsY have been proposed to catalyze the cotranslational targeting of proteins to the bacterial plasma membrane. A mutation was introduced into the GTP-binding domain of FtsY that altered its nucleotide specificity from GTP to xanthosine triphosphate (XTP). The mutant FtsY protein stimulated GTP hydrolysis by a ribonucleoprotein consisting of Ffh and 4.5S RNA in a reaction that required XTP, and it hydrolyzed XTP in a reaction that required both the Ffh-4.5S ribonucleoprotein and GTP. Thus, nucleotide triphosphate hydrolysis by Ffh and FtsY is likely to occur in reciprocally coupled reactions in which the two interacting guanosine triphosphatases act as regulatory proteins for each other.
authors.affiliation: Department of Biochemistry and Biophysics, University of California Medical School, San Francisco 94143-0448, USA.
authors.forename: T
authors.initials: T
authors.lastname: Powers
authors.forename: P
authors.initials: P
authors.lastname: Walter
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004789:Enzyme Activation; D029968:Escherichia coli Proteins; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009154:Mutation; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012265:Ribonucleotides / Q000378:metabolism / Q000494:pharmacology; D018271:Signal Recognition Particle / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C082931:Ffh protein, E coli; C087406:FtsY protein, Bacteria; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D012265:Ribonucleotides; D018271:Signal Recognition Particle; C065326:xanthosine 5'-triphosphate; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins