Delayed-relaxed response explained by hyperactivation of RelE

被引:45
作者
Christensen, SK [1 ]
Gerdes, K [1 ]
机构
[1] Univ So Denmark, Dept Biochem & Mol Biol, DK-5230 Odense M, Denmark
关键词
D O I
10.1111/j.1365-2958.2004.04127.x
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Escherichia coli encodes two rel loci, both of which contribute to the control of synthesis of macromolecules during amino acid starvation. The product of relA (ppGpp synthetase I) is responsible for the synthesis of guanosine tetraphosphate, ppGpp, the signal molecule that exerts stringent control of stable RNA synthesis. The second rel locus, relBE, was identified by mutations in relB that confer a so-called 'delayed-relaxed response' characterized by continued RNA synthesis after a lag period of approximate to 10 min after the onset of amino acid starvation. We show here that the delayed-relaxed response is a consequence of hyperactivation of RelE. As in wild-type cells, [ppGpp] increased sharply in relB101 relE cells after the onset of starvation, but returned rapidly to the prestarvation level. RelE is a global inhibitor of translation that is neutralized by RelB by direct protein-protein interaction. Lon protease activates RelE during amino acid starvation by degradation of RelB. We found that mutations in relB that conferred the delayed-relaxed phenotype destabilized RelB. Such mutations confer severe RelE-dependent inhibition of translation during amino acid starvation, indicating hyperactivation of RelE. Hyperactivation of RelE during amino acid starvation was shown directly by measurement of RelE-mediated cleavage of tmRNA. The RelE-mediated shutdown of translation terminated amino acid consumption and explains the rapid restoration of the ppGpp level observed in relB mutant cells. Restoration of the prestarvation level of ppGpp, in turn, allows for the resumption of stable RNA synthesis seen during the delayed-relaxed response.
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页码:587 / 597
页数:11
相关论文
共 33 条
[21]   Role of inorganic polyphosphate in promoting ribosomal, protein degradation by the ion protease in E-coli [J].
Kuroda, A ;
Nomura, K ;
Ohtomo, R ;
Kato, J ;
Ikeda, T ;
Takiguchi, N ;
Ohtake, H ;
Kornberg, A .
SCIENCE, 2001, 293 (5530) :705-708
[22]   Inorganic polyphosphate kinase is required to stimulate protein degradation and for adaptation to amino acid starvation in Escherichia coli [J].
Kuroda, A ;
Tanaka, S ;
Ikeda, T ;
Kato, J ;
Takiguchi, N ;
Ohtake, H .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1999, 96 (25) :14264-14269
[23]  
LAVALLE R, 1976, CONTROL RIBOSOME SYN, P408
[24]   Sok antisense RNA from plasmid R1 is functionally inactivated by RNase E and polyadenylated by poly(A) polymerase I [J].
Mikkelsen, ND ;
Gerdes, K .
MOLECULAR MICROBIOLOGY, 1997, 26 (02) :311-320
[25]   Conditional senescence in bacteria:: death of the immortals [J].
Nyström, T .
MOLECULAR MICROBIOLOGY, 2003, 48 (01) :17-23
[26]   Rapid induction and reversal of a bacteriostatic condition by controlled expression of toxins and antitoxins [J].
Pedersen, K ;
Christensen, SK ;
Gerdes, K .
MOLECULAR MICROBIOLOGY, 2002, 45 (02) :501-510
[27]   The bacterial toxin RelE displays codon-specific cleavage of rnRNAs in the ribosomal A site [J].
Pedersen, K ;
Zavialov, AV ;
Pavlov, MY ;
Elf, J ;
Gerdes, K ;
Ehrenberg, M .
CELL, 2003, 112 (01) :131-140
[28]   TRICINE SODIUM DODECYL-SULFATE POLYACRYLAMIDE-GEL ELECTROPHORESIS FOR THE SEPARATION OF PROTEINS IN THE RANGE FROM 1-KDA TO 100-KDA [J].
SCHAGGER, H ;
VONJAGOW, G .
ANALYTICAL BIOCHEMISTRY, 1987, 166 (02) :368-379
[29]   CORRELATION BETWEEN HISTIDINE OPERON EXPRESSION AND GUANOSINE 5'-DIPHOSPHATE-3'-DIPHOSPHATE LEVELS DURING AMINO-ACID DOWNSHIFT IN STRINGENT AND RELAXED STRAINS OF SALMONELLA-TYPHIMURIUM [J].
SHAND, RF ;
BLUM, PH ;
MUELLER, RD ;
RIGGS, DL ;
WARTZ, SW .
JOURNAL OF BACTERIOLOGY, 1989, 171 (02) :737-743
[30]   GUANOSINE 5'-DIPHOSPHATE 3'-DIPHOSPHATE (PPGPP) - POSITIVE EFFECTOR FOR HISTIDINE OPERON TRANSCRIPTION AND GENERAL SIGNAL FOR AMINO-ACID DEFICIENCY [J].
STEPHENS, JC ;
ARTZ, SW ;
AMES, BN .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1975, 72 (11) :4389-4393