Eukaryotic HMGB proteins as replacements for HU in E. coli repression loop formation.
DNA looping is important for gene repression and activation in Escherichia coli and is necessary for some kinds of gene regulation and recombination in eukaryotes. We are interested in sequence-nonspecific architectural DNA-binding proteins that alter the apparent flexibility of DNA by producing transient bends or kinks in DNA. The bacterial heat unstable (HU) and eukaryotic high-mobility group B (HMGB) proteins fall into this category. We have exploited a sensitive genetic assay of DNA looping in living E. coli cells to explore the extent to which HMGB proteins and derivatives can complement a DNA looping defect in E. coli lacking HU protein. Here, we show that derivatives of the yeast HMGB protein Nhp6A rescue DNA looping in E. coli lacking HU, in some cases facilitating looping to a greater extent than is observed in E. coli expressing normal levels of HU protein. Nhp6A-induced changes in the DNA length-dependence of repression efficiency suggest that Nhp6A alters DNA twist in vivo. In contrast, human HMGB2-box A derivatives did not rescue looping.
Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905, USA.
Nicole A
NA
Becker
Jason D
JD
Kahn
L James
LJ
Maher
D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D024002:HMGB Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D024261:HMGB2 Protein / Q000737:chemistry / Q000235:genetics; D024001:HMGN Proteins; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics; D009875:Operator Regions, Genetic; D010641:Phenotype; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics; D017384:Sequence Deletion
D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D024002:HMGB Proteins; D024261:HMGB2 Protein; D024001:HMGN Proteins; C086471:NHP6A protein, S cerevisiae; D009687:Nuclear Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C116822:hns protein, E coli; D004247:DNA