Interference of mRNA function by sequence-specific endoribonuclease PemK.
In Escherichia coli, programmed cell death is mediated through the system called "addiction module," which consists of a pair of genes encoding a stable toxin and a labile antitoxin. The pemI-pemK system is an addiction module present on plasmid R100. It helps to maintain the plasmid by post-segregational killing in E. coli population. Here we demonstrate that purified PemK, the toxin encoded by the pemI-pemK addiction module, inhibits protein synthesis in an E. coli cell-free system, whereas the addition of PemI, the antitoxin against PemK, resumes the protein synthesis. Further studies reveal that PemK is a sequence-specific endoribonuclease that cleaves mRNAs to inhibit protein synthesis, whereas PemI blocks the endoribonuclease activity of PemK. PemK cleaves only single-stranded RNA preferentially at the 5' or 3' side of the A residue in the "UAH" sequences (where H is C, A, or U). Upon induction, PemK cleaves cellular mRNAs to effectively block protein synthesis in E. coli. The pemK homologue genes have been identified on the genomes of a wide range of bacteria. We propose that PemK and its homologues form a novel endoribonuclease family that interferes with mRNA function by cleaving cellular mRNAs in a sequence-specific manner.
Zhang
Junjie
J
Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
Zhang
Yonglong
Y
Zhu
Ling
L
Suzuki
Motoo
M
Inouye
Masayori
M
D001483:Base Sequence; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D007700:Kinetics; D014176:Protein Biosynthesis / Q000235:genetics; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment
D017931:DNA Primers; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C080273:PemK protein, E coli; D012329:RNA, Bacterial; D012333:RNA, Messenger; D004722:Endoribonucleases