A RecB-family nuclease motif in the Type I restriction endonuclease EcoR124I.
The Type I restriction-modification enzyme EcoR124I is an ATP-dependent endonuclease that uses dsDNA translocation to locate and cleave distant non-specific DNA sites. Bioinformatic analysis of the HsdR subunits of EcoR124I and related Type I enzymes showed that in addition to the principal PD-(E/D)xK Motifs, I, II and III, a QxxxY motif is also present that is characteristic of RecB-family nucleases. The QxxxY motif resides immediately C-terminal to Motif III within a region of predicted alpha-helix. Using mutagenesis, we examined the role of the Q and Y residues in DNA binding, translocation and cleavage. Roles for the QxxxY motif in coordinating the catalytic residues or in stabilizing the nuclease domain on the DNA are discussed.
Sisáková
Eva
E
Institute of Microbiology v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Stanley
Louise K
LK
Weiserová
Marie
M
Szczelkun
Mark D
MD
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D004247:DNA / Q000378:metabolism; D015253:Deoxyribonucleases, Type I Site-Specific / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D043211:Exodeoxyribonuclease V / Q000737:chemistry; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D021122:Protein Subunits / Q000737:chemistry; D021381:Protein Transport; D016415:Sequence Alignment
D021122:Protein Subunits; D004247:DNA; D043211:Exodeoxyribonuclease V; C048242:endodeoxyribonuclease EcoR124I; D015253:Deoxyribonucleases, Type I Site-Specific