Recruitment of HU by piggyback: a special role of GalR in repressosome assembly.
In Gal repressosome assembly, a DNA loop is formed by the interaction of two GalR, bound to two distal operators, and the binding of the histone-like protein, HU, to an architecturally critical position on DNA to facilitate the GalR-GalR interaction. We show that GalR piggybacks HU to the critical position on the DNA through a specific GalR-HU interaction. This is the first example of HU making a specific contact with another protein. The GalR-HU contact that results in cooperative binding of the two proteins to DNA may be transient and absent in the final repressosome structure. A sequence-independent DNA-binding protein being recruited to an architectural site on DNA through a specific association with a regulatory protein may be a common mode for assembly of complex nucleoprotein structures.
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Department of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4255, USA.
Adhya
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D000596:Amino Acids / Q000737:chemistry; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D002875:Chromosomes / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D005966:Glucuronidase / Q000378:metabolism; D008954:Models, Biological; D008957:Models, Genetic; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011487:Protein Conformation; D012097:Repressor Proteins / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic
D000596:Amino Acids; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C050993:Galactose repressor proteins; D012097:Repressor Proteins; C116822:hns protein, E coli; D004247:DNA; D005966:Glucuronidase