title: Identification of essential arginine residues of Escherichia coli DedA/Tvp38 family membrane proteins YqjA and YghB.
abstract: Escherichia coli DedA/Tvp38 family proteins YghB and YqjA are putative membrane transporters with 62% amino acid identity and overlapping functions. An E. coli strain (BC202) with nonpolar ΔyghB and ΔyqjA mutations displays cell-division defects and temperature sensitivity and is sensitive to antibiotics and alkaline pH. In this study, we performed site-directed mutagenesis on conserved, charged amino acids of YqjA and YghB. We discovered two conserved predicted membrane-embedded arginines (R130 and R136) that are critical for function in both proteins as defined by their ability to complement BC202 phenotypes, when expressed from a plasmid. Lysine can substitute for arginine at position R130 indicating a charge dependence at this position, but could not substitute at R136. In light of the established role that arginine plays in the translocation mechanism of numerous membrane transporters, we hypothesize that these amino acids play a role in the transport mechanism of these DedA/Tvp38 family proteins.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: Sujeet
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: Cersten L
authors.initials: CL
authors.lastname: Bradley
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: Patience
authors.initials: P
authors.lastname: Mukashyaka
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA wdoerr@lsu.edu.
authors.forename: William T
authors.initials: WT
authors.lastname: Doerrler
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001120:Arginine / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000737:chemistry / Q000187:drug effects / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009154:Mutation
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C530999:YghB protein, E coli; C531000:YqjA protein, E coli; D001120:Arginine; D008239:Lysine
keywords: alkaline tolerance; antibiotic resistance; membrane transport; site-directed mutagenesis