6p0s
Crystal structure of ternary DNA complex "FX2" containing E. coli Fis and phage lambda XisCrystal structure of ternary DNA complex "FX2" containing E. coli Fis and phage lambda Xis
Structural highlights
FunctionFIS_ECOLI Activates ribosomal RNA transcription, as well other genes. Plays a direct role in upstream activation of rRNA promoters. Binds to a recombinational enhancer sequence that is required to stimulate hin-mediated DNA inversion. Prevents initiation of DNA replication from oriC.[1] [2] Publication Abstract from PubMedLocalized arrays of proteins cooperatively assemble onto chromosomes to control DNA activity in many contexts. Binding cooperativity is often mediated by specific protein-protein interactions, but cooperativity through DNA structure is becoming increasingly recognized as an additional mechanism. During the site-specific DNA recombination reaction that excises phage lambda from the chromosome, the bacterial DNA architectural protein Fis recruits multiple lambda-encoded Xis proteins to the attR recombination site. Here, we report X-ray crystal structures of DNA complexes containing Fis + Xis, which show little, if any, contacts between the two proteins. Comparisons with structures of DNA complexes containing only Fis or Xis, together with mutant protein and DNA binding studies, support a mechanism for cooperative protein binding solely by DNA allostery. Fis binding both molds the minor groove to potentiate insertion of the Xis beta-hairpin wing motif and bends the DNA to facilitate Xis-DNA contacts within the major groove. The Fis-structured minor groove shape that is optimized for Xis binding requires a precisely positioned pyrimidine-purine base-pair step, whose location has been shown to modulate minor groove widths in Fis-bound complexes to different DNA targets. Cooperative DNA binding by proteins through DNA shape complementarity.,Hancock SP, Cascio D, Johnson RC Nucleic Acids Res. 2019 Sep 19;47(16):8874-8887. doi: 10.1093/nar/gkz642. PMID:31616952[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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