title: Improvement in K+-limited growth rate associated with expression of the N-terminal fragment of one subunit (KdpA) of the multisubunit Kdp transporter in Escherichia coli.
abstract: Mutations in any one of three genes, kdpA, -B, or -C, in Escherichia coli abolish the activity of Kdp, a multisubunit K+-ATPase that belongs to the P-type ATPase family of cation transporters. We found in this study that expression in vivo of a 135-amino-acid-long N-terminal fragment (KdpA'), less than one-quarter the length of native KdpA, was able to mediate an improvement in K+-limited growth rates in two different contexts, even in the absence of both KdpC and the ATPase subunit KdpB. The first context was when KdpA' was overexpressed in cells from a heterologous inducible promoter, and the second was when KdpA' was provided with a C-terminally altered extension (following a spontaneous genetic rearrangement). Our results suggest that KdpA' provides an incipient pathway for K+ translocation which can serve to transport K+ into the cells in response to the cytoplasmic membrane potential.
authors.affiliation: Centre for Cellular and Molecular Biology, Hyderabad 500 007, India.
authors.forename: A A
authors.initials: AA
authors.lastname: Sardesai
authors.forename: J
authors.initials: J
authors.lastname: Gowrishankar
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins; D003470:Culture Media; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D011188:Potassium / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D002352:Carrier Proteins; D027682:Cation Transport Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D000251:Adenosine Triphosphatases; C058166:potassium translocating Kdp-ATPase, E coli; D011188:Potassium