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Half-life of Escherichia coli polyadenylated lipoprotein mRNA
J Taljanidisz1, P Shen, N Sarkar
1Boston Biomedical Research Institute, MA 02114, USA.
Abstract:
In the light of recent evidence that the half-life of bacterial mRNA may be modulated by polyadenylation at the 3' end, we determined the half-life of polyadenylated lpp mRNA, which is an abundant and comparatively stable message encoding a major lipoprotein of the outer membrane. Messenger RNAs were pulse-labeled with [3H] adenosine and poly(A) RNA was isolated at various times after pulse-labeling by affinity chromatography on oligo(dT) cellulose. The amount of lpp mRNA remaining was quantitated by hybridization with the antisense strand of the lpp gene cloned in M13mp18. The observed half-life for polyadenylated lpp mRNA was 12 min. This represents the first half-life measurement for a specific polyadenylated mRNA in E. coli, and is slightly longer than the half-life of total lpp RNA reported earlier. It coincides with the functional half-life for lpp mRNA determined by Inouye and coworkers by measuring the rate of lipoprotein synthesis at various times after rifampicin addition. This suggest that polyadenylated lpp RNA is the predominant and translationally active form of lpp mRNA within the cell.
Insights
Polyadenylation influences bacterial mRNA stability. This study measured the half-life of polyadenylated lpp mRNA in E. coli, finding it to be 12 minutes, suggesting it is the primary active form.
Area of Science:
- Molecular Biology
- Bacterial Genetics
Background:
- Recent evidence suggests polyadenylation modulates bacterial mRNA half-life.
- Lipoprotein (lpp) mRNA encodes a major outer membrane lipoprotein in E. coli.
- Understanding mRNA stability is crucial for bacterial gene regulation.
Purpose of the Study:
- To determine the half-life of polyadenylated lpp mRNA in E. coli.
- To investigate the role of polyadenylation in lpp mRNA stability and translational activity.
Main Methods:
- Pulse-labeling of bacterial mRNA with [3H] adenosine.
- Isolation of polyadenylated RNA using oligo(dT) cellulose affinity chromatography.
- Quantification of lpp mRNA levels via hybridization with a specific antisense probe.
Main Results:
- The measured half-life of polyadenylated lpp mRNA was 12 minutes.
- This is the first reported half-life for a specific polyadenylated mRNA in E. coli.
- The half-life is slightly longer than previously reported for total lpp RNA and matches its functional half-life.
Conclusions:
- Polyadenylated lpp mRNA is the predominant and translationally active form in E. coli.
- Polyadenylation appears to stabilize lpp mRNA, influencing its functional half-life.
- This finding contributes to understanding post-transcriptional regulation in bacteria.