Stringent control and growth-rate-dependent control have nonidentical promoter sequence requirements.
AUTOR(ES)
Josaitis, C A
RESUMO
Escherichia coli uses at least two regulatory systems, stringent control and growth-rate-dependent control, to adjust rRNA output to amino acid availability and the steady-state growth rate, respectively. We examined transcription from rrnB P1 promoters containing or lacking the cis-acting UP element and FIS protein binding sites after amino acid starvation. The "core promoter" responds to amino acid starvation like the full-length wild-type promoter; thus, neither the UP element nor FIS plays a role in stringent control. To clarify the relationship between growth-rate-dependent regulation and stringent control, we measured transcription from growth-rate-independent promoters during amino acid starvation. Four rrnB P1 mutants defective for growth-rate control and two other growth-rate-independent promoters (rrnB P2 and pS10) still displayed stringent regulation. Thus, the two systems have different promoter determinants, consistent with the idea that they function by different mechanisms. Two mutations disrupted stringent control of rrnB P1: (i) a multiple base change in the "discriminator" region between the -10 hexamer and the transcription start site and (ii) a double substitution making the promoter resemble the E sigma 70 consensus promoter. These results have important implications for the mechanisms of both stringent control and growth-rate-dependent control of rRNA transcription.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=42649Documentos Relacionados
- Translational regulation is responsible for growth-rate-dependent and stringent control of the synthesis of ribosomal proteins L11 and L1 in Escherichia coli.
- Identification of promoter mutants defective in growth-rate-dependent regulation of rRNA transcription in Escherichia coli.
- Growth-rate-dependent regulation of the expression and inactivation of thymidylate synthase in Saccharomyces cerevisiae.
- Growth-rate-dependent expression and cloning of gnd alleles from natural isolates of Escherichia coli.
- Growth-rate-dependent adjustment of ribosome function in chemostat-grown cells of the fungus Mucor racemosus.