The protein HU can displace the LexA repressor from its DNA‐binding sites

The major bacterial histone‐like protein HU is a small, basic, dimeric protein composed of two closely related subunits. HU is involved in several processes in the bacterial cell such as the initiation of replication, transposition, gene inversion and cell division. It has been suggested that HU could introduce structural changes to the DNA which would facilitate or inhibit the binding of regulatory proteins to their specific sites. In this study we investigated the effect of HU on the binding of LexA protein, the regulator of SOS functions, to three of its specific binding sites. We show that HU can displace LexA from its binding sites on the operators of the lexA, recA and sfiA genes. The lexA operator was the most sensitive while the higher affinity sfiA operator was the least sensitive. Since HU, like its homologue IHF, probably binds DNA in the minor groove we tested the effect of distamycin, a drug which binds to the minor groove, on LexA binding. Like HU, this drug disrupted LexA–operator complexes. These results suggest that distortion of the minor groove of the lexA operators excludes the binding of the repressor to the major groove.

[1]  J. W. Little.  The SOS Regulatory System , 1996 .

[2]  T. Megraw,et al.  Functional complementarity between the HMG1-like yeast mitochondrial histone HM and the bacterial histone-like protein HU. , 1993, The Journal of biological chemistry.

[3]  M. Haykinson,et al.  DNA looping and the helical repeat in vitro and in vivo: effect of HU protein and enhancer location on Hin invertasome assembly. , 1993, The EMBO journal.

[4]  C. Lazdunski,et al.  DNA sequence determinants of LexA-induced DNA bending. , 1993, Nucleic acids research.

[5]  M. Beltrame,et al.  Protein HU binds specifically to kinked DNA , 1993, Molecular microbiology.

[6]  M. Granger-Schnarr,et al.  LexA, the Self-Cleaving Transcriptional Repressor of the SOS System , 1993 .

[7]  E. Bonnefoy,et al.  HU, the major histone‐like protein of E. coli, modulates the binding of IHF to oriC. , 1992, The EMBO journal.

[8]  A. Kornberg,et al.  Opening of the replication origin of Escherichia coli by DnaA protein with protein HU or IHF. , 1992, The Journal of biological chemistry.

[9]  J. Rouvière-Yaniv,et al.  Role of the histone-like proteins OsmZ and HU in homologous recombination. , 1992, Gene.

[10]  U. K. Laemmli,et al.  In vivo topoisomerase II cleavage of the Drosophila histone and satellite III repeats: DNA sequence and structural characteristics. , 1992, The EMBO journal.

[11]  A. Dri,et al.  Inhibition of cell division in hupA hupB mutant bacteria lacking HU protein , 1991, Journal of bacteriology.

[12]  J. W. Little.  Mechanism of specific LexA cleavage: autodigestion and the role of RecA coprotease. , 1991, Biochimie.

[13]  E. Bonnefoy,et al.  HU and IHF, two homologous histone‐like proteins of Escherichia coli, form different protein‐DNA complexes with short DNA fragments. , 1991, The EMBO journal.

[14]  R. Lloubès,et al.  Interaction of a regulatory protein with a DNA target containing two overlapping binding sites. , 1991, The Journal of biological chemistry.

[15]  A. Toussaint,et al.  Multiple defects in Escherichia coli mutants lacking HU protein , 1989, Journal of bacteriology.

[16]  F. Imamoto,et al.  Participation of the hup gene product in site-specific DNA inversion in Escherichia coli. , 1989, Gene.

[17]  T. Baker,et al.  Transcriptional activation of initiation of replication from the E. coli chromosomal origin: An RNA-DNA hybrid near oriC , 1988, Cell.

[18]  G. de Murcia,et al.  Specific protein-DNA complexes: immunodetection of the protein component after gel electrophoresis and Western blotting. , 1988, Analytical biochemistry.

[19]  Jay D. Gralla,et al.  DNA dynamic flexibility and protein recognition: Differential stimulation by bacterial histone-like protein HU , 1988, Cell.

[20]  H. Nash,et al.  Synapsis of attachment sites during lambda integrative recombination involves capture of a naked DNA by a protein-DNA complex , 1988, Cell.

[21]  N. Kleckner,et al.  Tn10 transposition and circle formation in vitro , 1987, Cell.

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

[23]  J. W. Little,et al.  Lysine-156 and serine-119 are required for LexA repressor cleavage: a possible mechanism. , 1987, Proceedings of the National Academy of Sciences of the United States of America.

[24]  M. Simon,et al.  Host protein requirements for in vitro site-specific DNA inversion , 1986, Cell.

[25]  K. Mizuuchi,et al.  A defined system for the DNA strand-transfer reaction at the initiation of bacteriophage Mu transposition: protein and DNA substrate requirements. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[26]  M. Daune,et al.  Large-scale purification, oligomerization equilibria, and specific interaction of the LexA repressor of Escherichia coli. , 1985, Biochemistry.

[27]  R. Mache,et al.  Similarity between the bacterial histone‐like protein HU and a protein from spinach chloroplasts , 1984 .

[28]  D. Mount,et al.  The SOS regulatory system of Escherichia coli , 1982, Cell.

[29]  A. Aitken,et al.  Amino and carboxy terminal sequences of the DNA-binding protein HU from the Cyanobacterium Synechocystis PCC 6701 (ATCC 27170). , 1979, Biochemical and biophysical research communications.

[30]  C. Jacq,et al.  Characterization of a histone-like protein extracted from yeast mitochondria. , 1979, Proceedings of the National Academy of Sciences of the United States of America.

[31]  M. Yaniv,et al.  E. coli DNA binding protein HU forms nucleosome-like structure with circular double-stranded DNA , 1979, Cell.

[32]  J. Rouvière-Yaniv,et al.  Localization of the HU protein on the Escherichia coli nucleoid. , 1978, Cold Spring Harbor symposia on quantitative biology.

[33]  S. Nedospasov,et al.  Histone-like proteins in the purified Escherichia coli deoxyribonucleoprotein. , 1977, Nucleic acids research.

[34]  F. Gros,et al.  Characterization of a novel, low-molecular-weight DNA-binding protein from Escherichia coli. , 1975, Proceedings of the National Academy of Sciences of the United States of America.