Methylation-related Epigenetic Signals in Bacterial DNA

摘要: The term “epigenetic signals” may seem extraneous to the life-style of bacteria, because classic concept epigenetics has been applied changes in gene expression that govern differentiation and development (Waddington 1956). However, is often associated with DNA or chromatin structure (Holliday Pugh 1975; Riggs 1975), modification provided an attractive model for study epigenetic regulation. In prokaryotes, most common methylation: For instance, DNAs from enteric bacteria contain minor amounts 6-methyladenine 5-methylcytosine (Marinus 1987). Base modifications are formed by two classes methylases: (1) those restriction/modification systems (Bickle Kruger 1993) (2) methyltransferases do not have a restriction enzyme counterpart: Dam methylase (DNA adenine methyltransferase) Dcm cytosine methyltransferase). Both enzymes transfer methyl group S -adenosylmethionine base located specific, double-stranded sequences (Noyer-Weidner Trautner 1993). target 5′-GATC-3′ (Lacks Greenberg 1977; Hattman et al. 1978). methylates inner pentanucleotides 5′-CCAGG-3′ 5′-CCTGG-3′ (May 1975). While biological role remains largely unknown 1987; Noyer-Weidner 1993; Glasner 1995), methyltransferase known participate control many cellular processes: replication, chromosome segregation, mismatch repair, transcriptional regulation certain genes (for reviews, see Marinus Messer 1988; Barras 1989;