The regulation of the Escherichia coli mazEF promoter involves an unusual alternating palindrome.
The Escherichia coli mazEF system is a chromosomal "addiction module" that, under starvation conditions in which guanosine-3',5'-bispyrophosphate (ppGpp) is produced, is responsible for programmed cell death. This module specifies for the toxic stable protein MazF and the labile antitoxic protein MazE. Upstream from the mazEF module are two promoters, P(2) and P(3) that are strongly negatively autoregulated by MazE and MazF. We show that the expression of this module is positively regulated by the factor for inversion stimulation. What seems to be responsible for the negative autoregulation of mazEF is an unusual DNA structure, which we have called an "alternating palindrome." The middle part, "a," of this structure may complement either the downstream fragment, "b," or the upstream fragment, "c". When the MazE.MazF complex binds either of these arms of the alternating palindrome, strong negative autoregulation results. We suggest that the combined presence of the two promoters, the alternating palindrome structure and the factor for inversion stimulation-binding site, all permit the expression of the mazEF module to be sensitively regulated under various growth conditions.
Marianovsky
I
I
Department of Cellular Biochemistry, Hebrew University-Hadassah Medical School, Ein Kerem, Jerusalem, 91120 Israel.
Aizenman
E
E
Engelberg-Kulka
H
H
Glaser
G
G
D000992:Antitoxins; D017209:Apoptosis / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D004722:Endoribonucleases; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D034982:Integration Host Factors; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D011485:Protein Binding
D000992:Antitoxins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D034982:Integration Host Factors; C422954:MazE protein, E coli; C422955:MazF protein, E coli; C440502:integration host factor, E coli; D004722:Endoribonucleases