This chapter reviews the evidence for channels in bacteria and evaluates their roles in cell physiology. Ion channels may play important roles in protection against excessive turgor pressure across the membrane (MscL, MscS, and possibly KefA) and during detoxification of electrophilic compounds (KefB, KefC). Other channels, such as KcsA, may play important roles in potassium acquisition or in balancing the potassium gradient with the membrane potential. The reality of Kch as a channel can only be a subject for speculation. However, if it were to function as an outwardly-rectified channel it might participate in membrane re-polarization during periods of starvation or, given its resemblance to the Ca2+-regulated, Drosophila slo channel, there may be a role for this channel in signaling the Ca2+ status of the cell. Other phenomena in bacteria may have their source in transport systems with channel-like properties. Most prominent among these is the Trk potassium transport system in Escherichia coli. For each of the proteins their open state has different implications for the cell and consequently tight regulation of opening is very important. The porins are open most of the time and are more correctly designated pores.
|Title of host publication||Transport Processes in Eukaryotic and Prokaryotic Organisms|
|Number of pages||37|
|Publication status||Published - 1996|
|Name||Handbook of Biological Physics|
Bibliographical noteFunding Information:
The authors wish to thank Mike Ashford, Paul Blount, Frank Harold, Ching Kung, Wolf Epstein and Sergei Sukharevf or their critical reading of this manuscript and for sharing their insights in membrane bioenergeticas and channel function. The authors would like to thank the Wellcome Trust and the BBSRC for financial support for their research programme. In addition the group is indebted to the following who have provide helpful comments, encouragement, vital strains and technological expertise Evert Bakker, Wolf Epstein, Andrei Kubalski, Barry Holland, Hilde Schrempf, Julius Adler and Changhai Cui. In addition the group is indebted to the efforts of previous members of the group who have helped the story of KefA, KefB and KefC to emerge.