Details

Autor(en) / Beteiligte

• Tendeng, Christian
• Krin, Evelyne
• Soutourina, Olga A.
• Marin, Antoine
• Danchin, Antoine
• Bertin, Philippe N.

Titel

A Novel H-NS-like Protein from an Antarctic Psychrophilic Bacterium Reveals a Crucial Role for the N-terminal Domain in Thermal Stability

Ist Teil von

• The Journal of biological chemistry, 2003-05, Vol.278 (21), p.18754-18760

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2003

Quelle

MEDLINE

Beschreibungen/Notizen

• We describe here new members of the H-NS protein family identified in a psychrotrophic Acinetobacter spp. bacterium collected in Siberia and in a psychrophilic Psychrobacter spp. bacterium collected in Antarctica. Both are phylogenetically closely related to the HvrA and SPB Rhodobacter transcriptional regulators. Their amino acid sequence shares 40% identity, and their predicted secondary structure displays a structural and functional organization in two modules similar to that of H-NS in Escherichia coli. Remarkably, the Acinetobacter protein fully restores to the wild-type H-NS-dependent phenotypes, whereas the Psychrobacter protein is no longer able to reverse the effects of H-NS deficiency in an E. coli mutant strain above 30 °C. Moreover, in vitro experiments demonstrate that the ability of the Psychrobacter H-NS protein to bind curved DNA and to form dimers is altered at 37 °C. The construction of hybrid proteins containing the N- or the C-terminal part of E. coli H-NS fused to the C- or N-terminal part of the Psychrobacter protein demonstrates the role of the N-terminal domain in this process. Finally, circular dichroism analysis of purified H-NS proteins suggests that, as compared with the E. coli and Acinetobacter proteins, the α-helical domain displays weaker intermolecular interactions in the Psychrobacter protein, which may account for the low thermal stability observed at 37 °C.