title: Alternative arrangements of catalytic residues at the active sites of restriction enzymes.
abstract: A catalytic sequence motif PDX10-30(E/D)XK is found in many restriction enzymes. On the basis of sequence similarities and mapping of the conserved residues to the crystal structure of NgoMIV we suggest that residues D160, K182, R186, R188 and E195 contribute to the catalytic/DNA binding site of the Ecl18kI restriction endonuclease. Mutational analysis confirms the functional significance of the conserved residues of Ecl18kI. Therefore, we conclude that the active site motif 159VDX21KX12E of Ecl18kI differs from the canonical PDX10-30(E/D)XK motif characteristic for most of the restriction enzymes. Moreover, we propose that two subfamilies of endonucleases Ecl18kI/PspGI/EcoRII and Cfr10I/Bse634I/NgoMIV, specific, respectively, for CCNGG/CCWGG and RCCGGY/GCCGGC sites, share conserved active site architecture and DNA binding elements.
authors: Institute of Biotechnology, Graiciuno 8, 2028, Vilnius, Lithuania.
authors: Gintautas
authors: G
authors: Tamulaitis
authors: Alexander S
authors: AS
authors: Solonin
authors: Virginijus
authors: V
authors: Siksnys
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D020134:Catalytic Domain; D017124:Conserved Sequence; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D016415:Sequence Alignment
chemical_list: D000596:Amino Acids; D004247:DNA; C114636:endodeoxyribonuclease Ecl18kI; D015252:Deoxyribonucleases, Type II Site-Specific