Oligomerization of the chromatin‐structuring protein H‐NS

H‐NS is a major component of the bacterial nucleoid, involved in condensing and packaging DNA and modulating gene expression. The mechanism by which this is achieved remains unclear. Genetic data show that the biological properties of H‐NS are influenced by its oligomerization properties. We have applied a variety of biophysical techniques to study the structural basis of oligomerization of the H‐NS protein from Salmonella typhimurium. The N‐terminal 89 amino acids are responsible for oligomerization. The first 64 residues form a trimer dominated by an α‐helix, likely to be in coiled–coil conformation. Extending this polypeptide to 89 amino acids generated higher order, heterodisperse oligomers. Similarly, in the full‐length protein no single, defined oligomeric state is adopted. The C‐terminal 48 residues do not participate in oligomerization and form a monomeric, DNA‐binding domain. These N‐ and C‐terminal domains are joined via a flexible linker which enables them to function independently within the context of the full‐length protein. This novel mode of oligomerization may account for the unusual binding properties of H‐NS.

[1]  C. Dorman,et al.  Domain organization and oligomerization among H-NS-like nucleoid-associated proteins in bacteria. , 1999, Trends in microbiology.

[2]  D. Ussery,et al.  DNA Binding Is Not Sufficient for H-NS-mediated Repression ofproU Expression* , 1997, The Journal of Biological Chemistry.

[3]  M. Cusick,et al.  Domain structure and RNA annealing activity of the Escherichia coli regulatory protein StpA , 1998, Molecular microbiology.

[4]  A. Lupas.  Coiled coils: new structures and new functions. , 1996, Trends in biochemical sciences.

[5]  T. Mizuno,et al.  Systematic mutational analysis revealing the functional domain organization of Escherichia coli nucleoid protein H-NS. , 1996, Journal of molecular biology.

[6]  Dieter Suter,et al.  Two-dimensional chemical exchange and cross-relaxation spectroscopy of coupled nuclear spins , 1981 .

[7]  D. Ussery,et al.  The chromatin-associated protein H-NS. , 1994, Biochimie.

[8]  A. Danchin,et al.  Role of Escherichia coli histone-like nucleoid-structuring protein in bacterial metabolism and stress response--identification of targets by two-dimensional electrophoresis. , 1997, European journal of biochemistry.

[9]  C. Gualerzi,et al.  The oligomeric structure of nucleoid protein H‐NS is necessary for recognition of intrinsically curved DNA and for DNA bending , 1997, The EMBO journal.

[10]  T. Mizuno,et al.  Clarification of the dimerization domain and its functional significance for the Escherichia coli nucleoid protein H-NS. , 1997, Journal of molecular biology.

[11]  S W Lin,et al.  Vectors for selective expression of cloned DNAs by T7 RNA polymerase. , 1987, Gene.

[12]  D. Ussery,et al.  The chromatin‐associated protein H‐NS alters DNA topology in vitro. , 1994, The EMBO journal.

[13]  C. Higgins,et al.  The chromatin-associated protein H-NS interacts with curved DNA to influence DNA topology and gene expression , 1992, Cell.

[14]  T. Mizuno,et al.  Solution structure of the DNA binding domain of a nucleoid‐associated protein, H‐NS, from Escherichia coli , 1995, FEBS letters.

[15]  F. Studier,et al.  Use of bacteriophage T7 RNA polymerase to direct selective high-level expression of cloned genes. , 1986, Journal of molecular biology.

[16]  J. Sambrook,et al.  Molecular Cloning: A Laboratory Manual , 2001 .

[17]  X. Zeng,et al.  Buried asparagines determine the dimerization specificities of leucine zipper mutants. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[18]  W C Johnson,et al.  Information content in the circular dichroism of proteins. , 1981, Biochemistry.

[19]  C. Higgins,et al.  Protein H1: a role for chromatin structure in the regulation of bacterial gene expression and virulence? , 1990, Molecular microbiology.

[20]  T. Mizuno,et al.  An Escherichia coli protein that preferentially binds to sharply curved DNA. , 1990, Journal of biochemistry.

[21]  C. Richardson,et al.  A bacteriophage T7 RNA polymerase/promoter system for controlled exclusive expression of specific genes. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[22]  R M Williams,et al.  Molecular aspects of the E. coli nucleoid protein, H-NS: a central controller of gene regulatory networks. , 1997, FEMS microbiology letters.

[23]  C. Higgins,et al.  Histone-like protein H1 (H-NS), DNA supercoiling, and gene expression in bacteria , 1990, Cell.

[24]  Johnson Wc,et al.  Information content in the circular dichroism of proteins. , 1981 .

[25]  L. Bracco,et al.  Synthetic curved DNA sequences can act as transcriptional activators in Escherichia coli. , 1989, The EMBO journal.

[26]  K. Drlica,et al.  Histonelike proteins of bacteria. , 1987, Microbiological reviews.

[27]  C. Pon,et al.  Proteins from the prokaryotic nucleoid: primary and quaternary structure of the 15‐kD Escherichia coli DNA binding protein H‐NS , 1988, Molecular microbiology.

[28]  S. Grzesiek,et al.  NMRPipe: A multidimensional spectral processing system based on UNIX pipes , 1995, Journal of biomolecular NMR.

[29]  Ian R. Booth,et al.  A physiological role for DNA supercoiling in the osmotic regulation of gene expression in S. typhimurium and E. coli , 1988, Cell.

[30]  H. Buc,et al.  Probing the structure, function, and interactions of the Escherichia coli H-NS and StpA proteins by using dominant negative derivatives , 1996, Journal of bacteriology.

[31]  D. Pettijohn,et al.  Histone-like proteins and bacterial chromosome structure. , 1988, The Journal of biological chemistry.