Robust ParB Binding to Half- Sites in -A Mechanism for Retaining ParB on the Nucleoid?

Chromosome segregation in is assisted by the tripartite ParAB- system, composed of an ATPase (ParA), a DNA-binding protein (ParB) and its target sequence(s). ParB forms a nucleoprotein complex around four s () that overlaps and facilitates relocation of newly synthesized ori domains inside the cells by ParA. Remarkably, ParB of also binds to numerous heptanucleotides (half-s) scattered in the genome.

Diverse Partners of the Partitioning ParB Protein in Pseudomonas aeruginosa.

In the majority of bacterial species, the tripartite ParAB- system, composed of an ATPase (ParA), a DNA-binding protein (ParB), and its target sequence(s), assists in the chromosome partitioning. ParB forms large nucleoprotein complexes at (s), located in the vicinity of origin of chromosomal replication (), which after replication are subsequently positioned by ParA in cell poles. Remarkably, ParA and ParB participate not only in the chromosome segregation but through interactions with various cellular partners they are also involved in other cell cycle-related processes, in a species-specific manner.

Deciphering the Regulatory Circuits of RA3 Replication Module - Mechanisms of the Copy Number Control.

The RA3 plasmid, the archetype of IncU incompatibility group, represents a mosaic-modular genome of 45.9 kb. The replication module encompasses and (initiator) surrounded by two long repetitive sequences DR1 and DR2 of unknown function.

Alpha-Helical Protein KfrC Acts as a Switch between the Lateral and Vertical Modes of Dissemination of Broad-Host-Range RA3 Plasmid from IncU (IncP-6) Incompatibility Group.

KfrC proteins are encoded by the conjugative broad-host-range plasmids that also encode alpha-helical filament-forming KfrA proteins as exemplified by the RA3 plasmid from the IncU incompatibility group. The RA3 variants impaired in , , or both affected the host's growth and demonstrated the altered stability in a species-specific manner. In a search for partners of the alpha-helical KfrC protein, the host's membrane proteins and four RA3-encoded proteins were found, including the filamentous KfrA protein, segrosome protein KorB, and the T4SS proteins, the coupling protein VirD4 and ATPase VirB4.

Revealing biophysical properties of KfrA-type proteins as a novel class of cytoskeletal, coiled-coil plasmid-encoded proteins.

Background: DNA binding KfrA-type proteins of broad-host-range bacterial plasmids belonging to IncP-1 and IncU incompatibility groups are characterized by globular N-terminal head domains and long alpha-helical coiled-coil tails. They have been shown to act as transcriptional auto-regulators.

Results: This study was focused on two members of the growing family of KfrA-type proteins encoded by the broad-host-range plasmids, R751 of IncP-1β and RA3 of IncU groups.