Intron-encoded homing endonuclease I-TevI also functions as a transcriptional autorepressor.Edgell, D.R., Derbyshire, V., Van Roey, P., LaBonne, S., Stanger, M.J., Li, Z., Boyd, T.M., Shub, D.A., Belfort, M.
(2004) Nat Struct Mol Biol 11: 936-944
- PubMed: 15361856
- DOI: https://doi.org/10.1038/nsmb823
- Primary Citation of Related Structures:
- PubMed Abstract:
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.
Wadsworth Center, New York State Department of Health, Center for Medical Sciences, 150 New Scotland Avenue, Albany, New York 12208, USA.