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Sequential closure of the cytoplasm then periplasm during cell division in Escherichia coli
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Kungliga Tekniska Högskolan, Stockholm.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Show others and affiliations
2012 (English)In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 194, no 3, 584-586 p.Article in journal (Refereed) Published
Abstract [en]

To visualize the latter stages of cell division in live Escherichia coli, we have carried out Fluorescence Recovery After Photobleaching (FRAP) on 121 cells expressing cytoplasmic GFP and periplasmic mCherry. Our data show conclusively, that the cytoplasm is sealed prior to the periplasm during the division event.

Place, publisher, year, edition, pages
2012. Vol. 194, no 3, 584-586 p.
Keyword [en]
cell division, Escherichia coli, periplasm, FRAP
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
URN: urn:nbn:se:su:diva-62906DOI: 10.1128/JB.06091-11ISI: 000299309200005PubMedID: 22101847OAI: oai:DiVA.org:su-62906DiVA: diva2:445468
Note
5Available from: 2011-10-04 Created: 2011-10-04 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Cell division in Escherichia coli
Open this publication in new window or tab >>Cell division in Escherichia coli
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The Gram-negative bacterium Escherichia coli is a model system to describe the biochemistry and cell biology of cell division in bacteria. This process can be divided into three major steps. The first step involves the replication of the DNA, followed by an elongation step in which the cells become twice as long. In the last step the elongated cell constricts in the middle and the two daughter cells are separated. The cell division process in E. coli has been extensively studied for at least 50 years and a lot is known, however many details are still vague. New proteins involved in the process continue to be identified and the number of these proteins as well as the interactions among them are not yet fully known. It is therefore not completely understood how the contraction proceeds to form two daughter cells. In this thesis, I have carried out experiments that contribute to our understanding of cell division in E. coli. Using fluorescence microscopy I show that the contraction of the inner membrane in dividing E. coli proceeds in a linear fashion and that the periplasm closes after the cytoplasm. I have also analyzed the oligomeric state of two proteins involved in the cell division and I show that the early cell division protein ZipA can dimerize. This could explain how this protein can bundle FtsZ protofilaments, as it could bridge two protofilaments. Penicillin-binding protein 5 (PBP5) has been found to localize to the septum and it has been suggested to be connected to cell division. I have found that PBP5 forms a homo-oligomeric complex, most likely a dimer. The dimer can be modeled in a back-to-back conformation with the catalytic domains being flexible. This allows PBP5 to reach for pentapeptides of the peptidoglycan at different distances from the membrane. An understanding of the mechanisms used by the cell division proteins and their protein: protein interactions can be a first step towards determining new antibiotic targets.

Place, publisher, year, edition, pages
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2011. 61 p.
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
urn:nbn:se:su:diva-62908 (URN)978-91-7447-339-1 (ISBN)
Public defence
2011-11-18, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 14:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: Manuscript. Available from: 2011-10-27 Created: 2011-10-04 Last updated: 2011-10-18Bibliographically approved
2. Fluorescence Studies of Cell Division in Escherichia coli
Open this publication in new window or tab >>Fluorescence Studies of Cell Division in Escherichia coli
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In Escherichia coli the cell division is carried out by a large dynamic protein complex called the divisome. The divisome assembles in a two-step manner starting with the localization of the eukaryotic tubulin homologue FtsZ to the midcell. Together with other early arriving proteins FtsZ form an intermediate structure called the Z-ring. After a considerable time lag the divisome maturates fully by recruiting several other late arriving proteins before it starts to constrict the cell envelope that ultimately will lead to cytokinesis and the formation of two identical daughter cells. Despite of being objectives of extensive study over the last decades, understanding of the exact molecular roles of many of the divisome proteins is still lacking and to date there is very limited knowledge of the disassembly process of the divisome. In this thesis I have used various fluorescence microscopy based methods to better characterize the role of FtsZ and other divisome proteins during the final stages of the cell division. I have shown that FtsZ disassembles from the divisome prior to inner membrane closure indicating that it is not the force generator during this final step of division that it is widely thought to be. I have also shown that the disassembly of the divisome is a multistep process in which the proteins that arrive in the second step of divisome assembly also remain at the division septum longer than those proteins that arrive in the first step. These findings add new important information regarding the cell division and together they provide a more complete picture of this event that ultimately may lead to more efficient identification of novel antibiotic targets.

Place, publisher, year, edition, pages
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2014. 84 p.
Keyword
E. coli, Cell division, FtsZ, Fluorescence microscopy, FRAP
National Category
Biophysics
Research subject
Biophysics
Identifiers
urn:nbn:se:su:diva-102619 (URN)978-91-7447-852-5 (ISBN)
Public defence
2014-06-03, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius Väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.

Available from: 2014-05-12 Created: 2014-04-11 Last updated: 2014-05-13Bibliographically approved

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