title: Evidence of participation of McrB(S) in McrBC restriction in Escherichia coli K-12.
abstract: The McrBC restriction system has the ability to restrict DNA containing 5-hydroxymethylcytosine, N4-methylcytosine, and 5-methylcytosine at specific sequences. The mcrB gene produces two gene products. The complete mcrB open reading frame produces a 51-kDa protein (McrB(L)) and a 33-kDa protein (McrB(S)). The smaller McrB polypeptide is produced from an in-frame, internal translational start site in the mcrB gene. The McrB(S) sequence is identical to that of McrB(L) except that it lacks 161 amino acids present at the N-terminal end of the latter protein. It has been suggested that McrB(L) is the DNA binding restriction subunit. The function of McrB(S) is unknown, although there has been speculation that it plays some role in the modulation of McrBC restriction. Studies of the function of McrB(S) have been challenging since it is produced in frame with McrB(L). In this study, we tested the effects of underproduction (via antisense RNA) and overproduction (via gene dosage) of mcrBC gene products on restriction levels of the mcrBC+ strain JM107. Among the parameters monitored was the induction of SOS responses, which indicate of DNA damage. Evidence from this study suggests that McrB(S) is necessary for stabilization of the McrBC restriction complex in vivo.
authors.affiliation: Department of Biological Sciences, Nicholls State University, Thibodaux, Louisiana 70310, USA.
authors.forename: T P
authors.initials: TP
authors.lastname: Beary
authors.forename: H D
authors.initials: HD
authors.lastname: Braymer
authors.forename: E C
authors.initials: EC
authors.lastname: Achberger
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D018387:Codon, Initiator; D004262:DNA Restriction Enzymes / Q000378:metabolism*; D015280:DNA Restriction-Modification Enzymes / Q000378:metabolism*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D011485:Protein Binding; D014176:Protein Biosynthesis; D016372:RNA, Antisense / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D013014:SOS Response, Genetics
chemical_list: D001426:Bacterial Proteins; D018387:Codon, Initiator; D015280:DNA Restriction-Modification Enzymes; D029968:Escherichia coli Proteins; D016372:RNA, Antisense; D011994:Recombinant Proteins; C069326:mcrC protein, E coli; D004262:DNA Restriction Enzymes; C120301:McrBC endonuclease; C059678:mcrB protein, E coli