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A single residue mutation in Hha preserving structure and binding to H–NS results in loss of H–NS mediated gene repression properties
Author(s) -
Cordeiro Tiago N.,
Garcı'a Jesús,
Pons José-Ignacio,
Aznar Sonia,
Juárez Antonio,
Pons Miquel
Publication year - 2008
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/j.febslet.2008.07.037
Subject(s) - psychological repression , mutant , escherichia coli , operon , isoleucine , chemistry , lac operon , wild type , mutation , microbiology and biotechnology , gene , cysteine , biology , biochemistry , gene expression , amino acid , leucine , enzyme
In this study, we report that a single mutation of cysteine 18 to isoleucine (C18I) in Escherichia coli Hha abolishes the repression of the hemolysin operon observed in the wild‐type protein. The phenotype also includes a significant decrease in the growth rate of E. coli cells at low ionic strength. Other substitutions at this position (C18A, C18S) have no observable effects in E. coli growth or hemolysin repression. All mutants are stable and well folded and bind H–NS in vitro with similar affinities suggesting that Cys 18 is not directly involved in H–NS binding but this position is essential for the activity of the H–NS/Hha heterocomplexes in the regulation of gene expression.