8r0s
Structure of reverse transcriptase from Cauliflower Mosaic Virus in complex with RNA/DNA hybrid
Structural highlights
FunctionA0A2D2PYL0_9VIRU Encodes for at least two polypeptides: protease (PR) and reverse transcriptase (RT). The protease processes the polyprotein in cis. Reverse transcriptase is multifunctional enzyme that converts the viral RNA genome into dsDNA in viral cytoplasmic capsids. This enzyme displays a DNA polymerase activity that can copy either DNA or RNA templates, and a ribonuclease H (RNase H) activity that cleaves the RNA strand of RNA-DNA heteroduplexes in a partially processive 3'- to 5'-endonucleasic mode. Neo-synthesized pregenomic RNA (pgRNA) are encapsidated, and reverse-transcribed inside the nucleocapsid. Partial (+)DNA is synthesized from the (-)DNA template and generates the relaxed circular DNA (RC-DNA) genome. After budding and infection, the RC-DNA migrates in the nucleus, and is converted into a plasmid-like covalently closed circular DNA (cccDNA).[ARBA:ARBA00025678] Publication Abstract from PubMedReverse transcriptases (RTs) are enzymes with DNA polymerase and RNase H activities. They convert single-stranded RNA into double-stranded DNA and are key enzymes for the replication of retroviruses and retroelements. Caulimoviridae is a major family of plant-infecting viruses. Caulimoviruses have a circular dsDNA genome that is replicated by reverse transcription, but in contrast to retroviruses, they lack integrase. Caulimoviruses are related to Ty3 retroelements. Ty3 RT has been extensively studied structurally and biochemically, but corresponding information for caulimoviral RTs is unavailable. In the present study, we report the first crystal structure of cauliflower mosaic virus (CaMV) RT in complex with a duplex made of RNA and DNA strands (RNA/DNA hybrid). CaMV RT forms a monomeric complex with the hybrid, unlike Ty3 RT, which does so as a dimer. Results of the RNA-dependent DNA polymerase and DNA-dependent DNA polymerase activity assays showed that individual CaMV RT molecules are able to perform full polymerase functions. However, our analyses showed that an additional CaMV RT molecule needs to transiently associate with a polymerase-competent RT molecule to execute RNase H cuts of the RNA strand. Collectively, our results provide details into the structure and function of CaMV RT and describe how the enzyme compares to other related RTs. Structural and biochemical characterization of cauliflower mosaic virus reverse transcriptase.,Prabaharan C, Figiel M, Szczepanowski RH, Skowronek K, Zajko W, Thangaraj V, Chamera S, Nowak E, Nowotny M J Biol Chem. 2024 Jul 11:107555. doi: 10.1016/j.jbc.2024.107555. PMID:39002684[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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