The potassium binding protein Kbp is a cytoplasmic potassium sensor

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Ashraf, Khuram U. and Josts, Inokentijs and Mosbahi, Khedidja and Kelly, Sharon M. and Byron, Olwyn and Smith, Brian O. and Walker, Daniel (2016) The potassium binding protein Kbp is a cytoplasmic potassium sensor. Structure, 24 (5). pp. 741-749. ISSN 0969-2126 (https://doi.org/10.1016/j.str.2016.03.017)

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Abstract

Escherichia coli possesses a number of specific K+ influx and efflux systems that maintain an appropriate intracellular K+ concentration. Although regulatory mechanisms have been identified for a number of these transport systems, the exact mechanism through which K+ concentration is sensed in the cell remains unknown. In this work we show that Kbp (K+ binding protein, formerly YgaU), a soluble 16-kDa cytoplasmic protein from Escherichia coli, is a highly specific K+ binding protein and is required for normal growth in the presence of high levels of external K+. Kbp binds a single potassium ion with high specificity over Na+ and other metal ions found in biological systems, although, in common with K+ transporters, it also binds Rb+ and Cs+. Dissection of the K+ binding determinants of Kbp suggests a mechanism through which Kbp is able to sense changes in K+ concentration over the relevant range of intracellular K+ concentrations.

ORCID iDs

Ashraf, Khuram U., Josts, Inokentijs, Mosbahi, Khedidja, Kelly, Sharon M., Byron, Olwyn, Smith, Brian O. and Walker, Daniel ORCID logoORCID: https://orcid.org/0000-0002-4206-2942;
CORE (COnnecting REpositories)