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New in press

New in press

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 nuclease activity

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;

Key Publications

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

Chromosome organization by a conserved condensin–ParB system in the actinobacterium
Corynebacterium glutamicum

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

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

A novel component of the division-site selection system of Bacillus subtilis and a new mode of
action for the division inhibitor MinCD

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

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