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The Acinetobacter calcoaceticus NCIB8250 mop operon mRNA is differentially degraded, resulting in a higher level of
1Lehrstuhl für Mikrobiologie, Institut für Mikrobiologie, Biochemie und Genetik der Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Abstract:
The 7.5-kb polycistronic mop mRNA is differentially degraded in Acinetobacter calcoaceticus. The 4.9-kb 5' portion of the transcript contains the genes mopKLMNOP, encoding the multi-component phenol hydroxylase, and its 5' end decays three times faster than the 2.3-kb 3' portion encoding catechol 1,2-dioxygenase (catA). Larger amounts of the catA mRNA than the mopKLMNOP mRNA are present in the cells as a result of this processing. The site for endonucleolytic cleavage is located in the intercistronic region between mopP and catA, and contains a potential stem-loop structure and a putative RNase E cleavage site. Decay of the mop mRNA in Escherichia coli depends on RNase E. Thus, we propose that an RNase E-like activity is also present in A. calcoaceticus. Expression of MopN, one polypeptide of the multi-component phenol hydroxylase, interferes with growth of A. calcoaceticus. Thus, harmful expression of MopN may be reduced by rapid decay of its mRNA, indicating that mRNA processing contributes to differential gene expression in the large mop operon of A. calcoaceticus NCIB8250.
Insights
Differential mRNA decay in Acinetobacter calcoaceticus regulates gene expression. Rapid decay of mopKLMNOP mRNA, compared to catA mRNA, controls phenol hydroxylase production and aids cell growth.
Area of Science:
- Microbiology
- Molecular Biology
- Gene Regulation
Background:
- The mop mRNA in Acinetobacter calcoaceticus is a 7.5-kb polycistronic transcript.
- This transcript encodes both multi-component phenol hydroxylase (mopKLMNOP) and catechol 1,2-dioxygenase (catA).
Purpose of the Study:
- To investigate the differential degradation of the mop mRNA in Acinetobacter calcoaceticus.
- To identify the mechanisms and implications of mRNA processing in the mop operon.
Main Methods:
- Analysis of mRNA decay rates for different regions of the mop transcript.
- Identification of the endonucleolytic cleavage site and its structural features.
- Comparison of mop mRNA decay in Acinetobacter calcoaceticus and Escherichia coli.
Main Results:
- The 5' portion of the mop mRNA (mopKLMNOP) decays three times faster than the 3' portion (catA).
- An intercistronic region between mopP and catA, containing a stem-loop and a putative RNase E site, is identified as the cleavage site.
- RNase E-dependent decay of mop mRNA in E. coli suggests a similar RNase E-like activity in A. calcoaceticus.
Conclusions:
- mRNA processing contributes to differential gene expression within the mop operon.
- Rapid decay of mopKLMNOP mRNA likely mitigates the harmful effects of MopN polypeptide expression on cell growth.
- This mRNA processing mechanism plays a role in regulating the production of phenol hydroxylase in A. calcoaceticus NCIB8250.