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An RNA degradosome assembly in Caulobacter crescentus.

Hardwick SW, Chan VS, Broadhurst RW, Luisi BF - Nucleic Acids Res. (2010)

Bottom Line: These recognition 'microdomains' punctuate structurally an extensive region that is otherwise predicted to be natively disordered.Finally, we observe that the abundance of RNase E varies through the cell cycle, with maxima at morphological differentiation and cell division.This variation may contribute to the program of gene expression during cell division.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.

ABSTRACT
In many bacterial species, the multi-enzyme RNA degradosome assembly makes key contributions to RNA metabolism. Powering the turnover of RNA and the processing of structural precursors, the RNA degradosome has differential activities on a spectrum of transcripts and contributes to gene regulation at a global level. Here, we report the isolation and characterization of an RNA degradosome assembly from the α-proteobacterium Caulobacter crescentus, which is a model organism for studying morphological development and cell-cycle progression. The principal components of the C. crescentus degradosome are the endoribonuclease RNase E, the exoribonuclease polynucleotide phosphorylase (PNPase), a DEAD-box RNA helicase and the Krebs cycle enzyme aconitase. PNPase and aconitase associate with specific segments in the C-terminal domain of RNase E that are predicted to have structural propensity. These recognition 'microdomains' punctuate structurally an extensive region that is otherwise predicted to be natively disordered. Finally, we observe that the abundance of RNase E varies through the cell cycle, with maxima at morphological differentiation and cell division. This variation may contribute to the program of gene expression during cell division.

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Cell-cycle variation of RNase E. (Top) Representative western blots of RNase E, PNPase, aconitase and FliF protein abundance during the cell division cycle. The two maxima of RNase E abundance are marked at the top with +. (Bottom) Cartoon representation of the stages of C. crescentus cell division.
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Figure 6: Cell-cycle variation of RNase E. (Top) Representative western blots of RNase E, PNPase, aconitase and FliF protein abundance during the cell division cycle. The two maxima of RNase E abundance are marked at the top with +. (Bottom) Cartoon representation of the stages of C. crescentus cell division.

Mentions: The abundance of degradosome components during the cell division cycle was monitored in a synchronous C. crescentus culture by western blotting. A pattern of variation in the abundance of RNase E was apparent, with two distinct maxima: first at the point of differentiation between swarmer and stalked cell forms (∼30 min), and also prior to cell division (∼100 min). Strikingly, following the differentiation between swarmer and stalked forms the apparent level of RNase E in the cell drops to approximately one-third of the maximum amount, before returning to near-peak levels at the point of cell division (Figure 6). The same synchronous cell cultures were probed with an antibody against the flagellar protein FliF, and the expected loss of signal for FliF following the differentiation from swarmer to stalked cells, before peaking again towards the end of the cell division cycle, confirmed that the cultures were successfully synchronized.Figure 6.


An RNA degradosome assembly in Caulobacter crescentus.

Hardwick SW, Chan VS, Broadhurst RW, Luisi BF - Nucleic Acids Res. (2010)

Cell-cycle variation of RNase E. (Top) Representative western blots of RNase E, PNPase, aconitase and FliF protein abundance during the cell division cycle. The two maxima of RNase E abundance are marked at the top with +. (Bottom) Cartoon representation of the stages of C. crescentus cell division.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3045602&req=5

Figure 6: Cell-cycle variation of RNase E. (Top) Representative western blots of RNase E, PNPase, aconitase and FliF protein abundance during the cell division cycle. The two maxima of RNase E abundance are marked at the top with +. (Bottom) Cartoon representation of the stages of C. crescentus cell division.
Mentions: The abundance of degradosome components during the cell division cycle was monitored in a synchronous C. crescentus culture by western blotting. A pattern of variation in the abundance of RNase E was apparent, with two distinct maxima: first at the point of differentiation between swarmer and stalked cell forms (∼30 min), and also prior to cell division (∼100 min). Strikingly, following the differentiation between swarmer and stalked forms the apparent level of RNase E in the cell drops to approximately one-third of the maximum amount, before returning to near-peak levels at the point of cell division (Figure 6). The same synchronous cell cultures were probed with an antibody against the flagellar protein FliF, and the expected loss of signal for FliF following the differentiation from swarmer to stalked cells, before peaking again towards the end of the cell division cycle, confirmed that the cultures were successfully synchronized.Figure 6.

Bottom Line: These recognition 'microdomains' punctuate structurally an extensive region that is otherwise predicted to be natively disordered.Finally, we observe that the abundance of RNase E varies through the cell cycle, with maxima at morphological differentiation and cell division.This variation may contribute to the program of gene expression during cell division.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.

ABSTRACT
In many bacterial species, the multi-enzyme RNA degradosome assembly makes key contributions to RNA metabolism. Powering the turnover of RNA and the processing of structural precursors, the RNA degradosome has differential activities on a spectrum of transcripts and contributes to gene regulation at a global level. Here, we report the isolation and characterization of an RNA degradosome assembly from the α-proteobacterium Caulobacter crescentus, which is a model organism for studying morphological development and cell-cycle progression. The principal components of the C. crescentus degradosome are the endoribonuclease RNase E, the exoribonuclease polynucleotide phosphorylase (PNPase), a DEAD-box RNA helicase and the Krebs cycle enzyme aconitase. PNPase and aconitase associate with specific segments in the C-terminal domain of RNase E that are predicted to have structural propensity. These recognition 'microdomains' punctuate structurally an extensive region that is otherwise predicted to be natively disordered. Finally, we observe that the abundance of RNase E varies through the cell cycle, with maxima at morphological differentiation and cell division. This variation may contribute to the program of gene expression during cell division.

Show MeSH
Related in: MedlinePlus