Assembly of Kch, a putative potassium channel from Escherichia coli
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
ID 175738
Author(s) Lundbäck, Anna-Karin; Müller, Shirley A; Engel, Andreas; Hebert, Hans
Author(s) at UniBasel Engel, Andreas
Müller, Shirley
Year 2009
Title Assembly of Kch, a putative potassium channel from Escherichia coli
Journal Journal of structural biology
Volume 168
Number 2
Pages / Article-Number 288-93
Keywords Kch, RCK, Potassium channel, Membrane protein, Single particle, Negative stain, Electron microscopy, Mass measurement, STEM

Attempts to explore the structure and function of Kch, a putative potassium channel of Escherichia coli have yielded varying results; potassium-associated functions have been found in vivo but not in vitro. Here the kch gene is shown to produce two proteins, full-length Kch and the large C-terminal cytosolic domain (the RCK domain). Further, these two proteins are associated at the initial stages of purification. Previous structural studies of full-length Kch claim that the isolated protein forms large aggregates that are not suitable for analysis. The results presented here show that the purified protein sample, although heterogeneous, has one major population with a mass of about 400kDa, implying the presence of two Kch tetramers in a complex form. A three dimensional reconstruction at 25A based on electron microscopy data from negatively stained particles, revealed a 210A long and 95A wide complex in which the two tetrameric Kch units are linked by their RCK domains, giving rise to a large central ring of density. The formation of this dimer of tetramers on expression or during purification, may explain why attempts to reconstitute Kch into liposomes for activity measurements have failed.

Publisher Academic Press
ISSN/ISBN 1047-8477
Full Text on edoc No
Digital Object Identifier DOI 10.1016/j.jsb.2009.07.018
PubMed ID
ISI-Number WOS:000270865000008
Document type (ISI) Journal Article

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