Nature and mechanism of the in vivo oligomerization of nucleoid protein H-NS

• DOI: 10.1038/sj.emboj.7600754
• Publication Date: 2005-07-28T20:23:45Z
• Authors: Stefano Stella; Roberto Spurio; Maurizio Falconi; Cynthia L Pon; Claudio O Gualerzi
• Keywords: Nucleoid; Linker; Tetramer; Tetratricopeptide

Two types of two-hybrid systems demonstrate that the transcriptional repressor, nucleoid-associated protein H-NS (histone-like, nucleoid structuring protein) forms dimers and tetramers in vivo, the latter being the active form of the protein. The H-NS 'protein oligomerization' domain (N-domain) is unable to oligomerize in the absence of the intradomain linker while the 'DNA-binding' C-domain clearly displays a protein-protein interaction capacity, which contributes to H-NS tetramerization and which is lost following Pro115 mutation. Linker deletion or substitution with KorB linker abolishes H-NS oligomerization. A model describing H-NS dimerization and tetramerization based on all available data and suggesting the existence in the tetramer of a bundle of four alpha-helices, each contributed by an H-NS monomer, is presented.