Structural highlights
Function
REP_PCV2 Essential for the replication of viral ssDNA. The closed circular ssDNA genome is first converted to a superhelical dsDNA. Rep and/or Rep' binds a specific hairpin at the genome origin of replication. Introduces an endonucleolytic nick within the conserved sequence 5'-AGTATTAC-3' in the intergenic region of the genome, thereby initiating the rolling circle replication (RCR). Following cleavage, binds covalently to the 5'-phosphate of DNA as a tyrosyl ester. The cleavage gives rise to a free 3'-OH that serves as a primer for the cellular DNA polymerase. The polymerase synthesizes the (+) strand DNA by rolling circle mechanism. After one round of replication, a Rep-catalyzed nucleotidyl transfer reaction releases a circular single-stranded virus genome, thereby terminating the replication. Displays origin-specific DNA cleavage, and nucleotidyl transferase.[1] [2]
Publication Abstract from PubMed
Replication initiator proteins (Reps) from the HUH-endonuclease superfamily process specific single-stranded DNA (ssDNA) sequences to initiate rolling circle/hairpin replication in viruses, such as crop ravaging geminiviruses and human disease causing parvoviruses. In biotechnology contexts, Reps are the basis for HUH-tag bioconjugation and a critical adeno-associated virus genome integration tool. We solved the first co-crystal structures of Reps complexed to ssDNA, revealing a key motif for conferring sequence specificity and for anchoring a bent DNA architecture. In combination, we developed a deep sequencing cleavage assay, termed HUH-seq, to interrogate subtleties in Rep specificity and demonstrate how differences can be exploited for multiplexed HUH-tagging. Together, our insights allowed engineering of only four amino acids in a Rep chimera to predictably alter sequence specificity. These results have important implications for modulating viral infections, developing Rep-based genomic integration tools, and enabling massively parallel HUH-tag barcoding and bioconjugation applications.
Molecular underpinnings of ssDNA specificity by Rep HUH-endonucleases and implications for HUH-tag multiplexing and engineering.,Tompkins KJ, Houtti M, Litzau LA, Aird EJ, Everett BA, Nelson AT, Pornschloegl L, Limon-Swanson LK, Evans RL, Evans K, Shi K, Aihara H, Gordon WR Nucleic Acids Res. 2021 Jan 25;49(2):1046-1064. doi: 10.1093/nar/gkaa1248. PMID:33410911[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Cheung AK. The essential and nonessential transcription units for viral protein synthesis and DNA replication of porcine circovirus type 2. Virology. 2003 Sep 1;313(2):452-9. PMID:12954212 doi:10.1016/s0042-6822(03)00373-8
- ↑ Cheung AK. Specific functions of the Rep and Rep׳ proteins of porcine circovirus during copy-release and rolling-circle DNA replication. Virology. 2015 Jul;481:43-50. PMID:25768890 doi:10.1016/j.virol.2015.01.004
- ↑ Tompkins KJ, Houtti M, Litzau LA, Aird EJ, Everett BA, Nelson AT, Pornschloegl L, Limón-Swanson LK, Evans RL, Evans K, Shi K, Aihara H, Gordon WR. Molecular underpinnings of ssDNA specificity by Rep HUH-endonucleases and implications for HUH-tag multiplexing and engineering. Nucleic Acids Res. 2021 Jan 25;49(2):1046-1064. PMID:33410911 doi:10.1093/nar/gkaa1248
