2ief
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Structure of the cooperative Excisionase (Xis)-DNA complex reveals a micronucleoprotein filament
OverviewOverview
The DNA architectural protein Xis regulates the construction of, higher-order nucleoprotein intasomes that integrate and excise the genome, of phage lambda from the Escherichia coli chromosome. Xis modulates the, directionality of site-specific recombination by stimulating phage, excision 10(6)-fold, while simultaneously inhibiting phage reintegration., Control is exerted by cooperatively assembling onto a approximately 35-bp, DNA regulatory element, which it distorts to preferentially stabilize an, excisive intasome. Here, we report the 2.6-A crystal structure of the, complex between three cooperatively bound Xis proteins and a 33-bp DNA, containing the regulatory element. Xis binds DNA in a head-to-tail, orientation to generate a micronucleoprotein filament. Although each, protomer is anchored to the duplex by a similar set of nonbase specific, contacts, malleable protein-DNA interactions enable binding to sites that, differ in nucleotide sequence. Proteins at the ends of the duplex sequence, specifically recognize similar binding sites and participate in, cooperative binding via protein-protein interactions with a bridging Xis, protomer that is bound in a less specific manner. Formation of this, polymer introduces approximately 72 degrees of curvature into the DNA with, slight positive writhe, which functions to connect disparate segments of, DNA bridged by integrase within the excisive intasome.
About this StructureAbout this Structure
2IEF is a Single protein structure of sequence from Enterobacteria phage lambda. Full crystallographic information is available from OCA.
ReferenceReference
Structure of the cooperative Xis-DNA complex reveals a micronucleoprotein filament that regulates phage lambda intasome assembly., Abbani MA, Papagiannis CV, Sam MD, Cascio D, Johnson RC, Clubb RT, Proc Natl Acad Sci U S A. 2007 Feb 13;104(7):2109-14. Epub 2007 Feb 7. PMID:17287355
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