Correlation between insertion mutant activities and amino acid sequence identities of the TaqI and TthHB8 restriction endonucleases.
A two-codon insertion mutagenesis method has been generalized. Over two dozen insertion mutants throughout the gene encoding TaqI restriction endonuclease were constructed and activity was characterized. All mutants with activity either cleaved or nicked the canonical T decreases CGA recognition sequence. Some insertion mutants created duplication of gene regions, termed Gemini proteins, which still retained activity. The correlation between mutants with poor activity and the regions of shared amino acid identity between the isoschizomeric TaqI and TthHB8I suggests these regions are involved in DNA recognition and/or catalysis.
Barany
F
F
Department of Microbiology, Hearst Microbiology Research Center, Cornell University Medical College, New York, NY 10021.
Zebala
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D003062:Codon / Q000235:genetics; D004252:DNA Mutational Analysis; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D016254:Mutagenesis, Insertional; D012689:Sequence Homology, Nucleic Acid; D013824:Thermus / Q000201:enzymology* / Q000235:genetics
D003062:Codon; D015252:Deoxyribonucleases, Type II Site-Specific; C027046:TCGA-specific type II deoxyribonucleases