2QOJ

Coevolution of a homing endonuclease and its host target sequence

Summary for 2QOJ

• Entry DOI: 10.2210/pdb2qoj/pdb
• Related: 1p8k
• Descriptor: LAGLIDADG endonuclease, I-AniI DNA target seq1, I-AniI DNA target seq2, ... (5 entities in total)
• Functional Keywords: laglidadg homing endonuclease, i-anii, hydrolase, intron homing, mitochondrion, mrna processing, mrna splicing, hydrolase-dna complex, hydrolase/dna
• Biological source: Emericella nidulans (strain FGSC A4 / ATCC 38163 / CBS 112.46 / NRRL 194 / M139) (Aspergillus nidulans); More
• Cellular location: Mitochondrion: H9D0N7
• Total number of polymer chains: 3
• Total formula weight: 48755.32

Authors

Scalley-Kim, M.,McConnell Smith, A.,Stoddard, B.L. (deposition date: 2007-07-20, release date: 2008-11-11, Last modification date: 2024-11-06)

Primary citation

Scalley-Kim, M.,McConnell-Smith, A.,Stoddard, B.L.
Coevolution of a homing endonuclease and its host target sequence.
J.Mol.Biol., 372:1305-1319, 2007

PubMed Abstract: We have determined the specificity profile of the homing endonuclease I-AniI and compared it to the conservation of its host gene. Homing endonucleases are encoded within intervening sequences such as group I introns. They initiate the transfer of such elements by cleaving cognate alleles lacking the intron, leading to their transfer via homologous recombination. Each structural homing endonuclease family has arrived at an appropriate balance of specificity and fidelity that avoids toxicity while maximizing target recognition and invasiveness. I-AniI recognizes a strongly conserved target sequence in a host gene encoding apocytochrome B and has fine-tuned its specificity to correlate with wobble versus nonwobble positions across that sequence and to the amount of degeneracy inherent in individual codons. The physiological target site in the host gene is not the optimal substrate for recognition and cleavage: at least one target variant identified during a screen is bound more tightly and cleaved more rapidly. This is a result of the periodic cycle of intron homing, which at any time can present nonoptimal combinations of endonuclease specificity and insertion site sequences in a biological host.

PubMed: 17720189
DOI: 10.1016/j.jmb.2007.07.052

Experimental method

X-RAY DIFFRACTION (2.4 Å)