6p0s
Crystal 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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