title: A new family of bacterial condensins.
abstract: 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.
authors.affiliation: Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA.
authors.forename: Zoya M
authors.initials: ZM
authors.lastname: Petrushenko
authors.forename: Weifeng
authors.initials: W
authors.lastname: She
authors.forename: Valentin V
authors.initials: VV
authors.lastname: Rybenkov
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D020090:Chromosome Segregation; D002876:Chromosomes, Bacterial / Q000378:metabolism*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D009876:Operon; D011110:Polymorphism, Genetic; D011485:Protein Binding; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000502:physiology*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D021122:Protein Subunits; C108312:condensin complexes; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases