The size of transcriptional units for ribosomal proteins in Escherichia coli

Autor: von Meyenburg K, Gullov K, Maaloe O, Molin S
Rok vydání: 1974
Předmět:
Zdroj: Molecular and General Genetics MGG. 129:11-26
ISSN: 1432-1874
0026-8925
DOI: 10.1007/bf00269262
Popis: An analysis of the degree to which the 55 ribosomal protein genes are clustered in polycistronic transcriptional units in E. coli is presented. Three kinetic approaches were applied: a) The labeling kinetics of RNA at different times after addition of rifampicin to a culture of E. coli growing in glucose minimal medium was used to calculate the distribution of transcribing RNA polymerases over different size classes of mRNA operons. The average length of transcriptional units being transcribed at a given time is about 3300 base pairs. Less than 1% of mRNA synthesis originates from transcriptional units longer than 12000 base pairs and only about 10% from units longer than 7500 base pairs. From this the upper limit of the length of ribosomal protein operons can be estimated. b) The rate of ribosomal protein synthesis as a fraction of the rate of total protein synthesis (αr) was measured during the cessation of mRNA synthesis and its decay after rifampicin addition. αr appears to decrease from 0.125 to 0.09 indicating that probably most ribosomal protein transcriptional units are shorter than the average. c) The kinetics of the rates of synthesis of individual ribosomal proteins was analysed after the release of the inhibition by rifampicin in a partially rifampicin resistant strain at 40°C. The rates of synthesis for all of the 40 ribosomal proteins tested reach half their final values at times falling in the interval 1.4–3.5 min, though for the majority it was reached between 1.6–2.6 min.
Databáze: OpenAIRE
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