Open AccessHeteromeric Interactions among Nucleoid-Associated Bacterial Proteins: Localization of StpA-Stabilizing Regions in H-NS ofEscherichia coli
Author(s) -
Jörgen Johansson,
Sven Eriksson,
Berit Sondén,
Sun Nyunt Wai,
Bernt Eric Uhlin
Publication year - 2001
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.183.7.2343-2347.2001
Subject(s) - homomeric , escherichia coli , biology , nucleoid , proteolysis , protease , prokaryote , proteases , protein subunit , biochemistry , microbiology and biotechnology , gene , enzyme
The nucleoid-associated proteins H-NS and StpA in Escherichia coli bind DNA as oligomers and are implicated in gene regulatory systems. There is evidence for both homomeric and heteromeric H-NS-StpA complexes. The two proteins show differential turnover, and StpA was previously found to be subject to protease-mediated degradation by the Lon protease. We investigated which regions of the H-NS protein are able to prevent degradation of StpA. A set of truncated H-NS derivatives was tested for their ability to mediate StpA stability and to form heteromers in vitro. The data indicate that H-NS interacts with StpA at two regions and that the presence of at least one of the H-NS regions is necessary for StpA stability. Our results also suggest that a proteolytically stable form of StpA, StpA(F21C), forms dimers, whereas wild-type StpA in the absence of H-NS predominantly forms tetramers or oligomers, which are more susceptible to proteolysis.