2ht0 | pdb_00002ht0
IHF bound to doubly nicked DNA
Structural highlights
Function[IHFB_ECOLI] One of the 2 subunits of integration host factor (IHF), a specific DNA-binding protein that functions in genetic recombination as well as in transcriptional and translational control.[1] [2] Plays a crucial role in the lysogenic life cycle of bacteriophage lambda, as it is required not only in the recombination reaction, which inserts lambda DNA into the E.coli chromosome, but also for the synthesis of int and cI repressor, two phage proteins necessary for DNA insertion and repression, respectively. The synthesis of int and cI proteins is regulated indirectly by IHF via translational control of the lambda cII protein.[3] [4] Has an essential role in conjugative DNA transfer (CDT), the unidirectional transfer of ssDNA plasmid from a donor to a recipient cell. It is the central mechanism by which antibiotic resistance and virulence factors are propagated in bacterial populations. Part of the relaxosome, which facilitates a site- and strand-specific cut in the origin of transfer by TraI, at the nic site. Relaxosome formation requires binding of IHF and TraY to the oriT region, which then faciliates binding of TraI.[5] [6] [IHFA_ECOLI] One of the 2 subunits of integration host factor (IHF), a specific DNA-binding protein that functions in genetic recombination as well as in transcriptional and translational control.[7] [8] Plays a crucial role in the lysogenic life cycle of bacteriophage lambda, as it is required not only in the recombination reaction, which inserts lambda DNA into the E.coli chromosome, but also for the synthesis of int and cI repressor, two phage proteins necessary for DNA insertion and repression, respectively. The synthesis of int and cI proteins is regulated indirectly by IHF via translational control of the lambda cII protein.[9] [10] Has an essential role in conjugative DNA transfer (CDT), the unidirectional transfer of ssDNA plasmid from a donor to a recipient cell. It is the central mechanism by which antibiotic resistance and virulence factors are propagated in bacterial populations. Part of the relaxosome, which facilitates a site- and strand-specific cut in the origin of transfer by TraI, at the nic site. Relaxosome formation requires binding of IHF and TraY to the oriT region, which then faciliates binding of TraI.[11] [12] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHU and IHF are prokaryotic proteins that induce very large bends in DNA. They are present in high concentrations in the bacterial nucleoid and aid in chromosomal compaction. They also function as regulatory cofactors in many processes, such as site-specific recombination and the initiation of replication and transcription. HU and IHF have become paradigms for understanding DNA bending and indirect readout of sequence. While IHF shows significant sequence specificity, HU binds preferentially to certain damaged or distorted DNAs. However, none of the structurally diverse HU substrates previously studied in vitro is identical with the distorted substrates in the recently published Anabaena HU(AHU)-DNA cocrystal structures. Here, we report binding affinities for AHU and the DNA in the cocrystal structures. The binding free energies for formation of these AHU-DNA complexes range from approximately 10-14.5 kcal/mol, representing K(d) values in the nanomolar to low picomolar range, and a maximum stabilization of at least approximately 6.3 kcal/mol relative to complexes with undistorted, non-specific DNA. We investigated IHF binding and found that appropriate structural distortions can greatly enhance its affinity. On the basis of the coupling of structural and relevant binding data, we estimate the amount of conformational strain in an IHF-mediated DNA kink that is relieved by a nick (at least 0.76 kcal/mol) and pinpoint the location of the strain. We show that AHU has a sequence preference for an A+T-rich region in the center of its DNA-binding site, correlating with an unusually narrow minor groove. This is similar to sequence preferences shown by the eukaryotic nucleosome. Structure-based analysis of HU-DNA binding.,Swinger KK, Rice PA J Mol Biol. 2007 Jan 26;365(4):1005-16. Epub 2006 Oct 13. PMID:17097674[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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