title: The N-terminal domain of the Caulobacter crescentus CgtA protein does not function as a guanine nucleotide exchange factor.
abstract: The Caulobacter crescentus GTP binding protein CgtA is a member of the Obg/GTP1 subfamily of monomeric GTP binding proteins. In vitro, CgtA displays moderate affinity for both GDP and GTP, and rapid exchange rate constants for either nucleotide. One possible explanation for the observed rapid guanine nucleotide exchange [corrected] rates is that CgtA is a bimodal protein with a C-terminal GTP binding domain and an N-terminal GEF domain. In this study we demonstrate that although the N-terminus of CgtA is required for function in vivo, this domain plays no significant role in the guanine nucleotide binding, exchange or GTPase activity.
authors.affiliation: Department of Biology, University of Michigan, 830 N University, Ann Arbor, MI 48109-1048, USA.
authors.forename: B
authors.initials: B
authors.lastname: Lin
authors.forename: J R
authors.initials: JR
authors.lastname: Maddock
mesh_terms: D000483:Alleles; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D016935:Caulobacter crescentus / Q000737:chemistry* / Q000201:enzymology; D005453:Fluorescence; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D020559:Monomeric GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D020662:Guanine Nucleotide Exchange Factors; D010446:Peptide Fragments; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; C108621:CgtA protein, bacteria; D020558:GTP Phosphohydrolases; D020559:Monomeric GTP-Binding Proteins