Identifying the catalytic residue of the ATPase reaction of DNA gyrase

摘要: Abstract We propose a mechanism for the hydrolysis of ATP by DNA gyrase B protein in which Glu42 acts as general base and His38 has role aligning polarizing glutamate residue. We have tested this site-directed mutagenesis, converting to Ala, Asp, Gln, Ala. In presence wild-type A protein, proteins bearing mutations Ala42 Gln42 show no detectable supercoiling or ATPase activities, while Asp42 Ala38 reduced activities. cleavage relaxation reactions gyrase, do not require hydrolysis, mutant similar When 43-kDa N-terminal fragment (which hydrolyzes ATP) contained Gln42, was bound but hydrolyzed, supporting idea that is involved nucleotide binding.