Functional mRNA half lives in E. coli

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Abstract
Summary Analysis of the synthetic rate of individual protein species at various times after complete inhibition of transcription with either streptolygidin or rifampicin was carried out by two-dimensional polyacrylamide electrophoresis of total Escherichia coli cell extracts. The decay rate of the potential to synthesize different proteins was assumed to be equal to the functional decay rate of the corresponding mRNA. We conclude the following: (a) The tufA and tufB messengers have different half lives (3.0 and 2.4 min, recpectively). (b) Different genes within the same transcriptional unit can have different half lives (S7, EFG and EFTuA — 2.5, 3.8 and 3.0 min, respectively). (c) There is at least a twenty-fold variation in individual mRNA half lives in E. coli; ribosomal protein Sl mRNA was observed to have the shortest half life in the cell (40 sec), while the longest observed half life was approximately 20 min (all values at 30°C). (d) addition of rifampicin increases the absolute rate of RNA polymerase subunit α and β synthesis twofold. (e) The induction of the synthesis of α subunit of RNA polymerase takes palce without a concomitant induction of ribosomal protein S4 and L17, which are reported to be on either side of α in the same transcriptional unit.