A new family of bacterial condensins

• Published in: Molecular microbiology 2011-08, Vol.81 (4), p.881-896
• Main Authors: Petrushenko, Zoya M., She, Weifeng, Rybenkov, Valentin V.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - chemistry; Adenosine Triphosphatases - genetics; Adenosine Triphosphatases - isolation & purification; Adenosine Triphosphatases - metabolism; Adenosine Triphosphate - metabolism; Bacteria; Bacteriology; Biological and medical sciences; Cells; Chromatin; Chromosome Segregation; Chromosomes; Chromosomes, Bacterial - metabolism; Cluster Analysis; Deoxyribonucleic acid; DNA; DNA, Bacterial - genetics; DNA, Bacterial - metabolism; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - isolation & purification; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Microbiology; Miscellaneous; Models, Biological; Multiprotein Complexes - chemistry; Multiprotein Complexes - genetics; Multiprotein Complexes - isolation & purification; Multiprotein Complexes - metabolism; Operon; Polymorphism, Genetic; Protein Binding; Protein Structure, Secondary; Protein Subunits - genetics; Pseudomonas aeruginosa; Pseudomonas aeruginosa - genetics; Pseudomonas aeruginosa - physiology; Sequence Analysis, DNA; Sequence Homology, Amino Acid
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2011.07763.x

Summary Condensins play a central role in global chromatin organization. In bacteria, two families of condensins have been identified, the MukBEF and SMC–ScpAB complexes. Only one of the two complexes is usually found in a given species, giving rise to a paradigm that a single condensin organizes bacterial chromosomes. Using sequence analysis, we identified a third family of condensins, MksBEF (MukBEF‐like SMC proteins), which is broadly present in diverse bacteria. The proteins appear distantly related to MukBEF, have a similar operon organization and similar predicted secondary structures albeit with notably shorter coiled‐coils. All three subunits of MksBEF exhibit significant sequence variation and can be divided into a series of overlapping subfamilies. MksBEF often coexists with the SMC–ScpAB, MukBEF and, sometimes, other MksBEFs. In Pseudomonas aeruginosa, both SMC and MksB contribute to faithful chromosome partitioning, with their inactivation leading to increased frequencies of anucleate cells. Moreover, MksBEF can complement anucleate cell formation in SMC‐deficient cells. Purified PaMksB showed activities typical for condensins including ATP‐modulated DNA binding and condensation. Notably, DNA binding by MksB is negatively regulated by ATP, which sets it apart from other known SMC proteins. Thus, several specialized condensins might be involved in organization of bacterial chromosomes.