Generation and evaluation of a large mutational library from the Escherichia coli mechanosensitive channel of large conductance, MscL: implications for channel gating and evolutionary design.
Random mutagenesis of the mechanosensitive channel of large conductance (MscL) from Escherichia coli coupled with a high-throughput functional screen has provided new insights into channel structure and function. Complementary interactions of conserved residues proposed in a computational model for gating have been evaluated, and important functional regions of the channel have been identified. Mutational analysis shows that the proposed S1 helix, despite having several highly conserved residues, can be heavily mutated without significantly altering channel function. The pattern of mutations that make MscL more difficult to gate suggests that MscL senses tension with residues located near the lipid headgroups of the bilayer. The range of phenotypical changes seen has implications for a proposed model for the evolutionary origin of mechanosensitive channels.
Maurer
Joshua A
JA
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Dougherty
Dennis A
DA
D000595:Amino Acid Sequence; D017124:Conserved Sequence; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D015723:Gene Library; D015640:Ion Channel Gating / Q000502:physiology*; D007473:Ion Channels / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010641:Phenotype; D017434:Protein Structure, Tertiary
D029968:Escherichia coli Proteins; D007473:Ion Channels; C086596:MscL protein, E coli