Disease relevance of chpA

• chpA and chpB, Escherichia coli chromosomal homologs of the pem locus responsible for stable maintenance of plasmid R100 [1].
• A study on the sigmaB operon of Staphylococcus aureus showed that the mazF gene of this organism is cotranscribed with the sigmaB operon in response to heat shock, providing the first example that the expression of the mazEFlocus might be indeed associated with stress responses [2].
• mazF, a novel counter-selectable marker for unmarked chromosomal manipulation in Bacillus subtilis [3].

High impact information on chpA

• Here we show that the chromosomal genes mazE and mazF, located in the Escherichia coli rel operon, have all of the properties required for an addiction module [4].
• Thus, induction of relE transcription severely inhibited translation, whereas induction of chpAK transcription inhibited both translation and replication [5].
• The chpA (mazEF) locus of Escherichia coli has been described as a cell killing module that induces bacterial apoptosis during nutritional stress [6].
• Based on these results, it was suggested that rather than inducing cell death, mazF induces a state of reversible bacteriostasis (K. Pederson, S. K. Christensen, and K. Gerdes, Mol. Microbiol. 45:501-510, 2002) [7].
• parD and chpA are homologous conditional killer systems of plasmid and chromosomal origin, respectively, encoding a killer protein (Kid and ChpAK) and an antidote (Kis and ChpAI) [8].

Biological context of chpA

• Following in vitro mutagenesis with hydroxylamine, chpA mutants that improve this complementation were isolated [8].
• mazEF is a toxin-antitoxin module located on the Escherichia coli chromosome and that of some other bacteria, including pathogens. mazF specifies for a stable toxin, MazF, and mazE specifies for a labile antitoxin, MazE, that antagonizes MazF [9].

Associations of chpA with chemical compounds

• The mazF gene was placed under the control of an isopropyl-beta-D-thiogalactopyranoside (IPTG)-inducible expression system and associated with a spectomycin-resistance gene to form the MazF cassette, which was flanked by two directly-repeated (DR) sequences [3].

References