Open AccessCytosine Methylation by the Sua I Restriction-Modification System: Implications for Genetic Fidelity in a Hyperthermophilic Archaeon
Author(s) -
Dennis W. Grogan
Publication year - 2003
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.185.15.4657-4661.2003
Subject(s) - biology , hyperthermophile , methylation , genetics , sulfolobus acidocaldarius , dna , dna methylation , cytosine , 5 methylcytosine , endonuclease , biochemistry , archaea , microbiology and biotechnology , gene , gene expression
5-methylcytosine in chromosomal DNA represents a potential source of frequent spontaneous mutation for hyperthermophiles. To determine the relevance of this threat for the archaeon Sulfolobus acidocaldarius, the mode of GGCC methylation by its restriction-modification system, SuaI, was investigated. Distinct isoschizomers of the SuaI endonuclease were used to probe the methylation state of GGCC in native S. acidocaldarius DNA. In addition, the methylation sensitivity of the SuaI endonuclease was determined with synthetic oligonucleotide substrates and modified natural DNAs. The results show that the SuaI system uses N(4) methylation to block cleavage of its recognition site, thereby avoiding the creation of G. T mismatches by spontaneous deamination at extremely high temperature.