Identification of the CTAG-recognizing restriction-modification systems MthZI and MthFI from Methanobacterium thermoformicicum and characterization of the plasmid-encoded mthZIM gene.
Two CTAG-recognizing restriction and modification (R/M) systems, designated MthZI and MthFI, were identified in the thermophilic archaeon Methanobacterium thermoformicicum strains Z-245 and FTF, respectively. Further analysis revealed that the methyltransferase (MTase) genes are plasmid-located in both strains. The plasmid pFZ1-encoded mthZIM gene of strain Z-245 was further characterized by subcloning and expression studies in Escherichia coli followed by nucleotide sequence analysis. The mthZIM gene is 1065 bp in size and may code for a protein of 355 amino acids (M(r) 42,476 Da). The deduced amino acid sequence of the M.MthZI enzyme shares substantial similarity with four distinct regions from several m4C- and m6A-MTases, and contains the TSPPY motif that is so far only found in m4C-MTases. Partially overlapping with the mthZIM gene and in reverse orientation, an additional ORF was identified with a size of 606 bp potentially coding for a protein of 202 amino acids (M(r) 23.710 Da). This ORF is suggested to encode the corresponding endonuclease R.MthZI.
Nölling
J
J
Department of Microbiology, Wageningen Agricultural University, The Netherlands.
de Vos
W M
WM
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D017014:Methanobacterium / Q000201:enzymology* / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D004269:DNA, Bacterial; C040836:CTAG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific