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Gene Review:

I-TevI - DNA endonuclease encoded by group 1A...

Enterobacteria phage T4

Dean, A.B. et al., Mueller, J.E. et al., Edgell, D.R. et al., Bechhofer, D.H. et al., Kreuzer, K.N. et al., et al.

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Disease relevance of I-TevI

Homing of the phage T4 td intron is initiated by the intron-encoded endonuclease I-TevI, which cleaves the intronless allele 23 and 25 nucleotides upstream of the intron insertion site (IS) [1].
I-TevI, the T4 phage GIY-YIG intron endonuclease, functions both in promoting td intron homing, and in acting as a transcriptional autorepressor [2].

High impact information on I-TevI

After the td intron endonuclease I-TevI cleaves the intronless recipient 23 and 25 nucleotides upstream of the intron insertion site, exonucleolytic degradation is required for recombination to proceed [3].
Intron-encoded endonuclease I-TevI binds as a monomer to effect sequential cleavage via conformational changes in the td homing site [4].
In situ cleavage assays and phasing analyses indicate that upon nicking the bottom strand of the td homing site, I-TevI induces a directed bend of 38 degrees towards the major groove near the cleavage site [4].
When the cleavage site (CS) is shifted outside a given range, wild-type I-TevI defaults to the fixed distance, whereas zinc-finger mutants have lost the distance determinant and search out the displaced cleavage sequences [5].
I-TevI consists of an N-terminal catalytic domain and a C-terminal DNA-binding domain separated by a long, flexible linker [5].

Biological context of I-TevI

For these experiments, we generated a novel phage strain that cleaves its own genome within the nonessential frd gene by means of the I-TevI endonuclease (encoded within the intron of the wild-type td gene) [6].
The beta 22 intron has a fragmentary open reading frame (ORF) that encodes a putative helix-turn-helix DNA-binding motif, similar to one at the carboxyl terminus of the homing endonuclease (I-TevI) encoded by the T4 td intron [7].
This site is an operator that overlaps the T4 late promoter, which drives I-TevI expression from within the td intron [8].
Here, we describe a novel, high-affinity binding site for I-TevI endonuclease, encoded within the group I td intron of phage T4 [8].

Associations of I-TevI with chemical compounds

Although counterintuitive, a protein containing a 19-aa deletion of the zinc finger can extend further than can wild-type I-TevI to cleave a distant CS sequence, and a Cys-to-Ala mutant of the ligands for zinc, nominally a longer protein, can retract to cleave at a closer CS sequence [5].

Enzymatic interactions of I-TevI

We found previously that I-TevI cleaves td delta In target DNA 23-26 nucleotides upstream of the intron insertion site [9].

Other interactions of I-TevI

Furthermore, we show that co-conversion tracts generated by repair of SegG and I-TevI double-strand breaks contribute to the localized exclusion of T2 markers [10].

References

Role of exonucleolytic degradation in group I intron homing in phage T4. Huang, Y.J., Parker, M.M., Belfort, M. Genetics (1999) [Pubmed]
Distance determination by GIY-YIG intron endonucleases: discrimination between repression and cleavage functions. Liu, Q., Derbyshire, V., Belfort, M., Edgell, D.R. Nucleic Acids Res. (2006) [Pubmed]
Exon coconversion biases accompanying intron homing: battle of the nucleases. Mueller, J.E., Smith, D., Belfort, M. Genes Dev. (1996) [Pubmed]
Intron-encoded endonuclease I-TevI binds as a monomer to effect sequential cleavage via conformational changes in the td homing site. Mueller, J.E., Smith, D., Bryk, M., Belfort, M. EMBO J. (1995) [Pubmed]
Zinc finger as distance determinant in the flexible linker of intron endonuclease I-TevI. Dean, A.B., Stanger, M.J., Dansereau, J.T., Van Roey, P., Derbyshire, V., Belfort, M. Proc. Natl. Acad. Sci. U.S.A. (2002) [Pubmed]
Recombination-dependent DNA replication stimulated by double-strand breaks in bacteriophage T4. Kreuzer, K.N., Saunders, M., Weislo, L.J., Kreuzer, H.W. J. Bacteriol. (1995) [Pubmed]
An intron in the thymidylate synthase gene of Bacillus bacteriophage beta 22: evidence for independent evolution of a gene, its group I intron, and the intron open reading frame. Bechhofer, D.H., Hue, K.K., Shub, D.A. Proc. Natl. Acad. Sci. U.S.A. (1994) [Pubmed]
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. Nat. Struct. Mol. Biol. (2004) [Pubmed]
I-TevI, the endonuclease encoded by the mobile td intron, recognizes binding and cleavage domains on its DNA target. Bell-Pedersen, D., Quirk, S.M., Bryk, M., Belfort, M. Proc. Natl. Acad. Sci. U.S.A. (1991) [Pubmed]
SegG endonuclease promotes marker exclusion and mediates co-conversion from a distant cleavage site. Liu, Q., Belle, A., Shub, D.A., Belfort, M., Edgell, D.R. J. Mol. Biol. (2003) [Pubmed]

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