Environmental control of the in vivo oligomerization of nucleoid protein H-NS.
The nucleoid-associated transcriptional repressor H-NS forms both dimers and tetramers in vivo. Two types of two-hybrid systems, one capable of detecting protein dimerization and the other protein tetramerization, have been used to determine whether environmental changes could affect the oligomerization capacity of this protein in the cell. Increasing the temperature from 37 degrees C to 48 degrees C and changing the pH between 4.0 and 9.0 did not influence either dimerization or tetramerization, whereas lowering the temperature below 25 degrees C and increasing osmolarity were found to reduce the formation of H-NS tetramers, which are the active form of this protein, without affecting dimerization. These findings provide a rationale to explain the induction of H-NS expression during cold-shock, suggest a mechanism contributing to derepressing osmotic-shock genes transcriptionally regulated by H-NS and indicate that changes of the oligomerization properties of H-NS do not play a role in the H-NS and temperature-dependent control of virulence gene expression.
Stella
Stefano
S
Laboratory of Genetics, Department of Biology MCA, University of Camerino, 62032 Camerino (MC), Italy.
Falconi
Maurizio
M
Lammi
Matilde
M
Gualerzi
Claudio O
CO
Pon
Cynthia L
CL
D001426:Bacterial Proteins / Q000378:metabolism*; D003080:Cold Temperature; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D009997:Osmotic Pressure; D012097:Repressor Proteins / Q000378:metabolism*; D013696:Temperature; D020798:Two-Hybrid System Techniques
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; D012097:Repressor Proteins