Rep-Type endonuclease

Cress-type Rep endonucleases are sequence-specific DNA binding proteins that recognize an ssDNA hairpin origin of replication. It is involved in the initiation of rolling circle replication by cleaving a strand of circular dsDNA, thereby releasing a 3'OH strand for polymerase initiation.

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Enzymatic reaction: All rep-type endonuclease belongs to the HUH-endonuclease superfamily. There are three class: Cress-type (Cressdnaviricota and Alphasatellitidae), Parvo -type (Piccovirales) and prokaryotic-type (Tubulavirales)

  • Tyr-endonuclease

Domain: Cress-type PFAM: PF02407
Gemini-type PFAM
Parvo-type PFAM: PF01057
Ino-type PFAM: PF05144
Micro-type PFAM: PF05840

Mechanism : The active site consists of an Tyrosine, a triad HUH or HUG (Histidine, hydrophobic, Histidine/Glutamine) and a Mg+ ion. The Tyr acts as a nucleophile and attacks the Phosphate atom of ssDNA strand at the top of an hairpin, while the mg+ ion assists the process by stabilizing the reaction intermediates. The result releases a 3'OH ssDNA strand, while the the other 5'Phosphate strand remains bound to the protein.

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Viral molecular biology Virus entry
Transcription and replication
Virus exit
Replication cycles
Virion
Enzymes
Significant viruses Sunburst PF02407

Cress-type: Porcine Circovirus 2 Rep
Parsing response... [0/0]

Parvo-type Parvovirus B19 Rep