Publication: Functional properties of KcsA R64 mutants
Authors
Kremer, Erica Catharina Everdina ; Montoya Díaz, Estafanía ; Molina Gallego, María Luisa ; Killian, J. Antoinette ; González Ros, José Manuel
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Publisher
Utrecht University
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DOI
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info:eu-repo/semantics/bookPart
Description
Abstract
The structural and functional properties of the potassium channel
KcsA from the bacterium Streptomyces lividans are known to be
influenced by lipids in various ways. Residue R64 in KcsA is implicated to
be part of the lipid binding pocket and is involved in tetramer stability
(chapter 4). In this study we investigated whether R64 is also involved in
channel functioning. For this purpose we analyzed the channel
conductance of two KcsA mutants (KcsA-R64D and KcsA-R64A) which
were reconstituted into giant asolectin vesicles. It was found that both
mutants had a similar conductance as KcsA-WT including the ability for
high and low open probability gating. However both mutant channels were
found to be less stable compared to KcsA-WT: the majority of KcsA-WT
channels gate during periods of time up to hours, whereas a large number
of mutant channels deactivates shortly after stimulation. This indicates
that R64 plays a role in conformational rearrangements that are necessary
for channel gating. Together the results suggest that gating and tetramer
stability are linked, and that lipid binding to R64 is an key feature for both.
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