The VirB4 family of proposed traffic nucleoside triphosphatases: common motifs in plasmid RP4 TrbE are essential for conjugation and phage adsorption.
Proteins of the VirB4 family are encoded by conjugative plasmids and by type IV secretion systems, which specify macromolecule export machineries related to conjugation systems. The central feature of VirB4 proteins is a nucleotide binding site. In this study, we asked whether members of the VirB4 protein family have similarities in their primary structures and whether these proteins hydrolyze nucleotides. A multiple-sequence alignment of 19 members of the VirB4 protein family revealed striking overall similarities. We defined four common motifs and one conserved domain. One member of this protein family, TrbE of plasmid RP4, was genetically characterized by site-directed mutagenesis. Most mutations in trbE resulted in complete loss of its activities, which eliminated pilus production, propagation of plasmid-specific phages, and DNA transfer ability in Escherichia coli. Biochemical studies of a soluble derivative of RP4 TrbE and of the full-length homologous protein R388 TrwK revealed that the purified forms of these members of the VirB4 protein family do not hydrolyze ATP or GTP and behave as monomers in solution.
Rabel
Christian
C
Max-Planck-Institut für Molekulare Genetik, Abteilung Lehrach, Ihnestrasse 73, Dahlem, D-14195 Berlin, Germany.
Grahn
A Marika
AM
Lurz
Rudi
R
Lanka
Erich
E
D017766:Acid Anhydride Hydrolases / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000327:Adsorption; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D001435:Bacteriophages / Q000502:physiology*; D001483:Base Sequence; D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D004247:DNA / Q000378:metabolism; D029968:Escherichia coli Proteins; D010861:Fimbriae, Bacterial / Q000502:physiology; D006160:Guanosine Triphosphate / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D043583:Nucleoside-Triphosphatase; D010957:Plasmids; D037521:Virulence Factors
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D037521:Virulence Factors; C074744:trbE protein, E coli; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D004247:DNA; D017766:Acid Anhydride Hydrolases; D043583:Nucleoside-Triphosphatase