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Pore mutations affecting tetrameric assembly and functioning of the potassium channel KcsA from Streptomyces lividans
Author(s) -
Splitt Heiner,
Meuser Dirk,
Borovok Ilya,
Betzler Michael,
Schrempf Hildgund
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01429-0
Subject(s) - kcsa potassium channel , mutant , alanine , leucine , residue (chemistry) , potassium channel , chemistry , amino acid , cysteine , methionine , valine , methanobacterium , biochemistry , biophysics , biology , ion channel , gene , enzyme , receptor , archaea
Designed mutations within the Streptomyces lividans kcsA gene resulted in a set of mutant proteins, which were characterized in respect to their assembly and channel activities. (i) The amino acid residue leucine 81 located at the external side of KcsA was found to be exchangeable by a cysteine residue without affecting the channel characteristics. (ii) Substitution of the first glycine (G77) residue within the GYG motif by an alanine or substitution of the tyrosine (Y) residue 78 by a phenylalanine (F) led to mutant proteins which form tetramers of reduced stability. In contrast to the AYG mutant protein, GFG functions as an active K + channel whose characteristics correspond to those of the wild‐type KcsA channel. (iii) The investigated mutant proteins, which carry different mutations (T72A, T72C, V76A, V76E, G77E, Y78A, G79A, G79D, G79E) within the signature sequence of the pore region, do not at all or only to a very small degree assemble as tetramers and lack channel activity.