1t2t
From Proteopedia
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Crystal structure of the DNA-binding domain of intron endonuclease I-TevI with operator site
Overview
Customary binding sites of intron-encoded homing endonucleases lie within cognate intronless alleles, at the so-called homing sites. Here, we describe a novel, high-affinity binding site for I-TevI endonuclease, encoded within the group I td intron of phage T4. This site is an operator that overlaps the T4 late promoter, which drives I-TevI expression from within the td intron. I-TevI binds the operator and homing sites with equal affinity, and functions as a transcriptional autorepressor. Distinct sequence and spacing requirements of the catalytic domain result in reduced cleavage activity on operator DNA. Crystallographic studies showed that the overall interactions of the DNA-binding domain with the operator and homing sites are similar, but have some different hydrogen-bonding contacts. We present a model in which the flexibility in protein-DNA interactions allows I-TevI to bind variant intronless alleles to promote intron mobility while facilitating its function in autorepression, and thereby persistence in its host.
About this Structure
1T2T is a Single protein structure of sequence from Bacteriophage t4 with as ligand. Full crystallographic information is available from OCA.
Reference
Intron-encoded homing endonuclease I-TevI also functions as a transcriptional autorepressor., Edgell DR, Derbyshire V, Van Roey P, LaBonne S, Stanger MJ, Li Z, Boyd TM, Shub DA, Belfort M, Nat Struct Mol Biol. 2004 Oct;11(10):936-44. Epub 2004 Sep 7. PMID:15361856
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