title: The XmnI restriction-modification system: cloning, expression, sequence organization and similarity between the R and M genes.
abstract: The xmnIRM genes from Xanthomonas manihotis 7AS1 have been cloned and expressed in Escherichia coli. The nucleotide (nt) sequences of both genes were determined. The XmnI methyltransferase (MTase)-encoding gene is 1861 bp in length and codes for 620 amino acids (aa) (68660 Da). The restriction endonuclease (ENase)-encoding gene is 959 bp long and therefore codes for a 319-aa protein (35275 Da). The two genes are aligned tail to tail and they overlap at their respective stop codons About 4 x 10(4) units/g wet cell paste of R.XmnI was obtained following IPTG induction in a suitable E. coli host. The xmnIR gene is expressed from the T7 promoter. M.XmnI probably modifies the first A in the sequence, GAA(N)4TTC. The xmnIR and M genes contain regions of conserved similarity and probably evolved from a common ancestor. M.XmnI is loosely related to M.EcoRI. The XmnI R-M system and the type-I R-M systems probably derived from a common ancestor.
authors.affiliation: New England Biolabs, Inc., Beverly, MA 01915, USA.
authors.forename: D O
authors.initials: DO
authors.lastname: Nwankwo
authors.forename: J J
authors.initials: JJ
authors.lastname: Lynch
authors.forename: L S
authors.initials: LS
authors.lastname: Moran
authors.forename: A
authors.initials: A
authors.lastname: Fomenkov
authors.forename: B E
authors.initials: BE
authors.lastname: Slatko
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004269:DNA, Bacterial; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics*; D004926:Escherichia coli; D019143:Evolution, Molecular; D015870:Gene Expression; D005798:Genes, Bacterial; D005807:Genes, Overlapping; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000235:genetics*; D013379:Substrate Specificity; D014974:Xanthomonas / Q000201:enzymology* / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; C101716:DNA modification methylase XmnI; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); C028649:endodeoxyribonuclease XmnI; D015252:Deoxyribonucleases, Type II Site-Specific