Overproduction of MazE has no effect in the absence of MazF [3]. Published reports disagree about whether MazF causes cell lysis in the absence of MazE [3] or whether the toxin causes reversible inhibition of cell growth, inhibiting translation and replication without causing cell inviability [7]. The MazE-MazF system mediates the toxicity of guanosine 3',5'-bispyrophosphate (rapid relA induction), which is associated with amino acid deprivation [3]; cell death caused by the antibiotics rifampicin, chloramphenicol, and spectinomycin [6]; and the thymineless death (TLD) response to thymine starvation [8]. The structure of the MazE-MazF complex is presented at 1.7 A resolution [9]. The complex is hexameric and is comprised of a MazE homodimer sandwiched between MazF homodimers [9]. MazE and MazF comigrate during native gel electrophoresis [3]. Protein-protein interactions in the MazE-MazF complex are discussed [9, 10]. It is proposed that the MazE monomer is less stably folded than the homodimer and that dimerization and associated structural changes may have an important role in protein activity [11]. The dimer interface has been structurally characterized [12]. The MazE N terminus is responsible for the DNA binding activity [10]. The MazE-DNA interaction has been characterized [10, 11], and the structure of the DNA binding domain is discussed [12]. Homology and genomic organization of similar antitoxin/toxin systems among bacteria has been reviewed [13]. MazE has similarity to episomal PemI [2]. Mutations in the N-terminal region of MazE affect its ability to suppress parD mutations in the episomal killer system [14]. Transcription of the mazEF "addiction module" is repressed by high concentrations of guanosine 3',5'-bispyrophosphate (ppGpp), suggesting that amino acid starvation induces lethality via RelA and the MazE-MazF system [3]. Thymine deprivation also represses mazEF transcription [8]. An autoinhibitory effect on transcription has been observed and an inversion mechanism also contributes to transcriptional regulation [1]. The lambda RexB protein has an inhibitory effect on ClpP-mediated proteolysis of MazE, increasing survival of lysogenized cells under conditions of amino acid deprivation [15]. Dromedary antibodies that recognize MazE have been generated [11]. MazE: "ma-ze" tr. "what is it?" in Hebrew [16] Reviews: [13, 17, 18]