title: Mechanism of cos DNA cleavage by bacteriophage lambda terminase: multiple roles of ATP.
abstract: In the terminus-generating (ter) reaction of phage lambda, the phage enzyme terminase catalyzes the production of staggered nicks within the cohesive-end nicking site (cosN). Although the two nicks are related by a rotational symmetry axis that bisects cosN, the in vitro ter reaction is strikingly asymmetric at the nucleotide level. Nicking of the lambda r strand precedes nicking of the I strand. Furthermore, when the two nicking reactions are uncoupled, they have different nucleotide cofactor requirements. ATP plays critical roles during cos cleavage: First, nicking of both DNA strands is stimulated by the addition of ATP. Second, ATP is required for the correct specificity of r-strand nicking since, in the absence of nucleotide, the r-strand nick is shifted 8 bases to the left. Studies with nonhydrolyzable analogs indicate that ATP hydrolysis is not required for these functions. However, after the two nicks are made, terminase catalyzes a disengagement of the cohered ends in a reaction that requires ATP hydrolysis.
authors.affiliation: Department of Medical Genetics, University of Toronto, Ontario, Canada.
authors.forename: R R
authors.initials: RR
authors.lastname: Higgins
authors.forename: H J
authors.initials: HJ
authors.lastname: Lucko
authors.forename: A
authors.initials: A
authors.lastname: Becker
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D010582:Bacteriophage lambda / Q000235:genetics*; D001483:Base Sequence; D004279:DNA, Viral / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000502:physiology*; D007700:Kinetics; D012045:Regulatory Sequences, Nucleic Acid; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000502:physiology*
chemical_list: D000227:Adenine Nucleotides; D004279:DNA, Viral; D014764:Viral Proteins; D000255:Adenosine Triphosphate; D004706:Endodeoxyribonucleases; C030894:terminase