Recombinant E.coli repD protein

RepD is a plasmid-encoded replication initiation protein originally identified in the rolling-circle replication (RCR) system of Staphylococcus aureus plasmids, such as pC221. It plays a critical role in initiating plasmid DNA replication by binding to a specific origin sequence (ori) and recruiting host-encoded helicases, like PriC, to unwind DNA. RepD belongs to the Rep family of proteins, which are essential for the replication of small, circular plasmids in Gram-positive bacteria. Its function is tightly regulated, as uncontrolled replication could destabilize the plasmid-host balance.

Structurally, RepD contains conserved domains for oligomerization, DNA binding, and helicase interaction. The N-terminal domain mediates sequence-specific DNA recognition at the origin, while the C-terminal region facilitates helicase loading. RepD’s activity is often controlled by antisense RNAs or accessory proteins to modulate plasmid copy number, reflecting its evolutionary adaptation to bacterial hosts.

Recombinant RepD (repD重组蛋白) refers to the protein produced via heterologous expression systems (e.g., E. coli) for biochemical and structural studies. Studies on recombinant RepD have clarified its molecular mechanism in replication initiation, including its dynamic interaction with DNA and helicases. This has broader implications for understanding plasmid biology, horizontal gene transfer, and antimicrobial resistance dissemination in pathogens. Additionally, RepD’s properties have inspired synthetic biology applications, such as designing minimal replication systems or gene-editing tools. Research continues to explore its potential in biotechnology and as a target for controlling plasmid-borne resistance genes.