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Asn 141 is essential for DNA recognition by Eco RI restriction endonuclease
Author(s) -
Fritz Andreas,
Küster Wolfgang,
Alves Jürgen
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01274-5
Subject(s) - serine , restriction enzyme , mutant , alanine , biochemistry , dna , endonuclease , chemistry , tyrosine , enzyme , wild type , residue (chemistry) , amino acid , stereochemistry , microbiology and biotechnology , biology , gene
The amino acid residue Asn 141 of the restriction endonuclease Eco RI was proposed to make three hydrogen bonds to both adenine residues within the recognition sequence ‐GAATTC‐. We have mutated Asn 141 to alanine, aspartate, serine, and tyrosine. Only the serine mutant is active under normal buffer conditions although 1000‐fold less than wild‐type Eco RI. The alanine and aspartate mutants can be activated by Mn 2+ . At acidic pH the latter mutant becomes even more active than the wild‐type enzyme in the presence of Mn 2+ . We conclude that Asn 141 is essential for DNA recognition and that serine can partly substitute it.