Disease relevance of pemK

• Upon induction, PemK cleaves cellular mRNAs to effectively block protein synthesis in E. coli [1].

High impact information on pemK

• The pemI-pemK system is an addiction module present on plasmid R100 [1].
• The pemK homologue genes have been identified on the genomes of a wide range of bacteria [1].
• The coexistence of the pem+ plasmid with a high-copy-number plasmid carrying the other open reading frame inhibited stabilization, and thus, the second open reading frame is a gene designated pemI, which encodes the inhibitor which might control the killing function of pemK [2].
• Inactivation of one of the two translational open reading frames in the pem region caused the loss of the killing function, and thus, the open reading frame is a gene designated pemK, which encodes the killing factor [2].

Biological context of pemK

• The low copy number plasmid R100 carries the pem region, consisting of two genes, pemI and pemK, which are required for stable maintenance of the plasmid [3].
• This indicates that pemK and pemI cistrons form an operon, and that the expression of the operon is negatively regulated by its own products [3].
• Plasmid R100 was found to have two genes, designated pemK and pemI, that were responsible for its stable inheritance during cell division [2].
• This indicates that both PemI and PemK proteins bind to the promoter region to autoregulate their synthesis [3].

Regulatory relationships of pemK

• 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 [1].

Analytical, diagnostic and therapeutic context of pemK

• We then conducted a gel retardation assay in vitro and found that the two pem products, each of which was obtained as a tripartite protein (PemI-collagen-LacZ and PemK-collagen-LacZ), bound cooperatively to a specific fragment containing the proximal region of the pem operon [3].

References