Esp1396I restriction-modification system: structural organization and mode of regulation

Abstract

Esp1396I restriction-modification (RM) system recognizes an interrupted palindromic DNA sequence 5'-CCA(N)(5)TGG-3'. The Esp1396I RM system was found to reside on pEsp1396, a 5.6 kb plasmid naturally occurring in Enterobacter sp. strain RFL1396. The nucleotide sequence of the entire 5622 bp pEsp1396 plasmid was determined on both strands. Identified genes for DNA methyltransferase (esp1396IM) and restriction endonuclease (esp1396IR) are transcribed convergently. The restriction endonuclease gene is preceded by the small ORF (esp1396IC) that possesses a strong helix-turn-helix motif and resembles regulatory proteins found in PvuII, BamHI and few other RM systems. Gene regulation studies revealed that C.Esp1396I acts as both a repressor of methylase expression and an activator of regulatory protein and restriction endonuclease expression. Our data indicate that C protein from Esp1396I RM system activates the expression of the Enase gene, which is co-transcribed from the promoter of regulatory gene, by the mechanism of coupled translation.

Restriction-Modification Systems as Minimal Forms of Life

“…Some C proteins also regulate their own synthesis (Kita et al 2002;Cesnaviciene et al 2003). Thus, these proteins may play a role in the establishment and auto-regulation of restriction-modification systems.…”

“…4.2.3), these proteins also have a helix-turn-helix domain that is probably responsible for DNA binding. Their modes of action and their recognition sites have been analyzed (Rimseliene et al 1995;O'Sullivan and Klaenhammer 1998;Bart et al 1999;Kita et al 2002;Cesnaviciene et al 2003). That C regulatory proteins actually participate in post-segregational killing has been demonstrated for EcoRV (Nakayama and Kobayashi 1998).…”

Overexpression, purification and preliminary X-ray diffraction analysis of the controller protein C.Csp231I fromCitrobactersp. RFL231

“…These helix-turn-helix proteins have been shown to act as regulators of both their own transcription and that of the restriction endonuclease (ENase) encoded within the same operon. In some cases, C proteins also regulate transcription of the methyltransferase (MTase; Tao et al, 1991;Ives et al, 1992;Rimšelienė et al, 1995;Lubys et al, 1999;Č esnavičienė et al, 2003;Semenova et al, 2005;Bogdanova et al, 2008).…”

Regulation of RNA Polymerase Promoter Selectivity by Covalent Modification of DNA

“…7 C proteins also positively regulate their own expression. 7,8 Thus, the presumably slow initial accumulation of C proteins allows sufficient time for methyltransferase gene expression, followed by stable activated expression of restriction endonuclease gene.…”