PUBLICATIONS
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The MksG nuclease is the executing part of the bacterial plasmid defense system MksBEFG
Cells are continuously facing the risk of taking up foreign DNA that can compromise genomic integrity. Therefore, bacteria are in a constant arms race with mobile genetic elements such as phages, transposons and plasmids. They have developed several active strategies against invading DNA molecules that can be seen as a bacterial ‘innate immune system’. Here, we investigated the molecular arrangement of the Corynebacterium glutamicum MksBEFG complex, which is homologous to the MukBEF condensin system. We show here that MksG is a nuclease that degrades plasmid DNA. The crystal structure of MksG revealed a dimeric assembly through its C-terminal domain that is homologous to the TOPRIM domain of the topoisomerase II family of enzymes and contains the corresponding ion binding site essential for DNA cleavage in topoisomerases. The MksBEF subunits exhibit an ATPase cycle in vitro and we reason that this reaction cycle, in combination with the nuclease activity provided by MksG, allows for processive degradation of invading plasmids. Super-resolution localization microscopy revealed that the Mks system is spatially regulated via the polar scaffold protein DivIVA. Introduction of plasmids results in an increase in DNA bound MksG, indicating an activation of the system in vivo.
MksG is the active nuclease subunit of the defense system.
Nuclease activity assays of MksG dimer, 5 μM protein were incubated 1 h at 30°C with 250 ng plasmid DNA (pJC1, 6108 bp) and 10 mM different divalent Metal-ions (second lane with Mn2+ only 1 mM). Reaction was stopped by adding 6x purple loading dye (NEB) and boiling samples 5 min at 90°C. DNA was separated on an agarose gel in TAE buffer. Assays for mutants (MksG (E236A), MksG (D279A), MksG (Y258A)) were incubated 3 h at 30°C.
Published in Nucleic Acids Research; https://doi.org/10.1093/nar/gkad130
Key publications
The MksG nuclease is the executing part of the bacterial plasmid defense system MksBEFG
Weiß M, Giacomelli G, Assaya MB, Grundt F, Haouz A, Peng F, Petrella S, Wehenkel AM, Bramkamp M
Nucleic Acids Res. 2023 Mar 7:gkad130. doi: 10.1093/nar/gkad130
A Bacterial Dynamin-Like Protein Confers a Novel Phage Resistance Strategy on the Population Level in Bacillus subtilis
Guo L, Sattler, L, Shafqat S, Graumann PL, Bramkamp M
mBio, 2022 13 (1):e0375321. doi: 10.1128/mbio.03753-21
Subcellular Dynamics of a Conserved Bacterial Polar Scaffold Protein
Giacomelli G*, Feddersen H*, Peng F, Martins GB, Grafemeyer M, Meyer F, Mayer B, Graumann PL, Bramkamp M. Genes (Basel). 2022 Jan 30;13(2):278. doi: 10.3390/genes13020278
The CTPase activity of ParB determines the size and dynamics of prokaryotic DNA partition complexes
Osorio-Valeriano M, Altegoer F, Das CK, Steinchen W, Panis G, Connolley L, Giacomelli G, Feddersen H, Corrales-Guerrero L, Giammarinaro PI, Hanßmann J, Bramkamp M, Viollier PH, Murray S, Schäfer LV, Bange G, Thanbichler M.Mol Cell. 2021 Oct 7;81(19):3992-4007.e10. doi: 10.1016/j.molcel.2021.09.004
Flotillin mediated membrane fluidity controls peptidoglycan synthesis and MreB movement
Zielińska A, Savietto A, de Sousa Borges A, Martinez D, Berbon M, Roelofsen JR, Hartman AM, de Boer R, van der Klei IJ, Hirsch AKH, Habenstein B, Bramkamp M, Scheffers D-J
Elife, 2020, 9:e57179. doi: 10.7554/eLife.57179
Böhm K, Giacomelli G, Schmidt A, Imhof A, Koszul R, Marbouty M, Bramkamp M
Nat Commun, 2020, 11(1):1485. doi: 10.1038/s41467–020–15238–4
The Antituberculosis Drug Ethambutol Selectively Blocks Apical Growth in CMN Group Bacteria
Schubert K, Sieger B, Meyer F, Giacomelli G, Böhm K, Rieblinger A, Lindenthal L, Sachs N, Wanner G, Bramkamp M
mBio, 2017 Feb 7, vol. 8 no. 1 e02213-16. doi: 10.1128/mBio.02213-16
A dynamin-like protein involved in bacterial cell membrane surveillance under environmental
stress
Sawant P, Eissenberger K, Karier L, Mascher T, Bramkamp M
Environ Microbiol, 2016, 18: 2705–2720. doi:10.1111/1462-2920.13110
A prophage-encoded actin-like protein required for efficient viral DNA replication in bacteria
Donovan C, Heyer A, Pfeifer E, Polen T, Wittmann A, Krämer R, Frunzke J, Bramkamp M
Nucleic Acids Res, 2015 Apr 27. pii: gkv374. doi: 10.1093/nar/gkv374
Flotillins functionally organize the bacterial membrane
Bach JN, Bramkamp M
Mol Microbiol, 2013 Jun, 88(6):1205-17. doi: 10.1111/mmi.12252
Bramkamp M, Emmins R, Weston L, Donovan C, Daniel RA, Errington J
Mol Microbiol, 2008 Dec, 70(6):1556-69. doi: 10.1111/j.1365-2958.2008.06501.x
Press releases
09/29/2022: New bacterial species discovered in the intestine
Researchers from MPI-EB Plön and Kiel University hope that the newly described species will provide a better understanding of the evolution of the genus Bacteroides as part of a healthy microbiota.
CAU press release: https://www.uni-kiel.de/en/university/details/news/142-unterweger-archmicrob
02/15/2022: Last line of defense: How bacterial populations are protected against viral infections
A research team from Kiel University describes how a bacterial dynamin protein is involved in a previously unknown protective mechanism against bacteriophage infections.
CAU press release: https://www.uni-kiel.de/en/university/details/news/021-bramkamp-mbio
11/16/2021: Previously unknown mode of bacterial growth discovered
Research teams from Kiel University’s Microbiology and the Universities of Amsterdam and Munich use imaging and modelling to explain why single bacterial cells do not always grow exponentially.
CAU press release: https://www.uni-kiel.de/en/university/details/news/251-meyer-elife
06/03/2021: Molecular powerhouse of the cell division motor
Interdisciplinary research teams from the Max-Planck-Institute of Biochemistry and the Institute of General Microbiology at Kiel University show that dynamic proteins can deform the cell membrane of bacterial cells and thus initiate cell division.
CAU press release: https://www.uni-kiel.de/en/university/details/news/124-ramirez-naturecomms
07/15/2020: How proteins regulate the outer envelope of bacterial cells
Research team in Kiel has identified the involvement of so-called flotillin proteins in the fluidization of bacterial cell membranes.
CAU press release: https://www.uni-kiel.de/en/university/details/news/173-zielinska-elife
03/20/2020: New piece of the puzzle in the architecture of life
Kiel research team investigates previously-unknown reproduction mechanism in the biotech-relevant bacterium Corynebacterium glutamicum.
CAU press release: https://www.uni-kiel.de/en/university/details/news/083-bramkamp-naturecomms
2017: Many forks make light work
LMU press release about new insights into the control of DNA replication and cell division in Corynebacterium glutamicum, a biotechnologically important microorganism, could help to optimize the industrial production of amino acids.
https://phys.org/news/2017-06-forks.html
2017: Lock-out on the building site
LMU press release about the selective block of apical growth in CMN group bacteria caused by the antituberculosis drug Ethambutol. Ethambutol has long been part of the standard therapy for tuberculosis. LMU researchers now describe how the antibiotic acts on the bacterium that causes the disease: It specifically inhibits growth of the cell wall from the cell poles.
