H-NS oligomerization domain structure reveals the mechanism for high order self-association of the intact protein |
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Authors: | Esposito Diego Petrovic Arsen Harris Richard Ono Shusuke Eccleston John F Mbabaali Amina Haq Ihtshamul Higgins Christopher F Hinton Jay C D Driscoll Paul C Ladbury John E |
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Affiliation: | Department of Biochemistry and Molecular Biology, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK. |
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Abstract: | H-NS plays a role in condensing DNA in the bacterial nucleoid. This 136 amino acid protein comprises two functional domains separated by a flexible linker. High order structures formed by the N-terminal oligomerization domain (residues 1-89) constitute the basis of a protein scaffold that binds DNA via the C-terminal domain. Deletion of residues 57-89 or 64-89 of the oligomerization domain precludes high order structure formation, yielding a discrete dimer. This dimerization event represents the initial event in the formation of high order structure. The dimers thus constitute the basic building block of the protein scaffold. The three-dimensional solution structure of one of these units (residues 1-57) has been determined. Activity of these structural units is demonstrated by a dominant negative effect on high order structure formation on addition to the full length protein. Truncated and site-directed mutant forms of the N-terminal domain of H-NS reveal how the dimeric unit self-associates in a head-to-tail manner and demonstrate the importance of secondary structure in this interaction to form high order structures. A model is presented for the structural basis for DNA packaging in bacterial cells. |
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Keywords: | chromatin coiled-coil DNA packaging nucleoid assembly histone-like |
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