title: The putative Walker A and Walker B motifs of Rrp2 are required for the growth of Borrelia burgdorferi.
abstract: Rrp2 encodes a putative bacterial enhancer binding protein (bEBP) in Borrelia burgdorferi. Point mutation (G239C) of Rrp2 abolishes the transcriptional activation of σ54-dependent rpoS. In contrast to canonical bEBPs that are dispensable for bacterial growth, Rrp2 is essential for borrelial growth in BSK medium. It has been believed that Rrp2's ATPase activity is not required for cell growth, but experimental evidence supporting this notion has been lacking. In particular, it has remained unclear whether the residue G239 is involved in Rrp2's presumptive ATPase activity. To address these information gaps, we examined the roles of Rrp2's potential strategic signatures including the G239 residue and the putative Walker A and Walker B motifs. Herein it was showed that Rrp2 has ATP binding and hydrolysis activities engendered by the Walker A and B motifs respectively. However, these activities were not significantly impaired by a G239C mutation. Further mutagenesis analyses indicated that Rrp2's Walker A and B motifs are required for borrelial growth; mutations of key residues in these two motifs were lethal to B. burgdorferi. The combined data suggest that the Walker A and Walker B motifs of Rrp2 are involved in the control of another unknown RpoS-independent gene product(s) associated with borrelial replication.
authors.affiliation: Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Ouyang
authors.affiliation: Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
authors.forename: Jianli
authors.initials: J
authors.lastname: Zhou
mesh_terms: D020816:Amino Acid Motifs; D000942:Antigens, Bacterial / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D025065:Borrelia burgdorferi / Q000254:growth & development / Q000378:metabolism*; D004261:DNA Replication / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D016296:Mutagenesis; D009154:Mutation; D051877:RNA Polymerase Sigma 54 / Q000235:genetics; D012808:Sigma Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C069567:sigma factor KatF protein, Bacteria; D051877:RNA Polymerase Sigma 54