RP4 plasmid (RP4)

The RP4 plasmid is a 60 kb self-transmissible IncPα plasmid with an extremely broad host range, stably maintained in Gram-negative bacteria and capable of conjugative DNA transfer to Gram-positive bacteria and yeasts. It encodes two main transfer regions, Tra1 and Tra2: Tra1 handles DNA processing via a relaxosome at the origin of transfer (oriT), involving proteins like TraI (relaxase), TraH, TraJ, and TraK, while Tra2 (core region with trbB-L genes) and traF form the mating pair formation (Mpf) system, creating a membrane-spanning apparatus for cell-to-cell contact, pilus production, and DNA transport through inner and outer membranes. Most Mpf proteins localize to the outer membrane, with TrbB in soluble/cytoplasmic membrane fractions, forming a multicomponent complex akin to a type IV secretion system (T4SS). RP4 serves as a model for plasmid biology and shares similarities with Agrobacterium Ti plasmid Vir regions for T-DNA transfer. It is not a human therapeutic target but a tool in synthetic biology for engineering conjugation in bacteria like E. coli and Pseudomonas. No drugs target RP4 directly, as it functions in bacterial genetics rather than human disease pathways.

Other names

IncPα plasmid RP4promiscuous IncP plasmid