Function and Structural Organization of the Replication Protein of Bamboo mosaic virus

Abstract

The genus Potexvirus is one of the eight genera belonging to the family Alphaflexiviridae according to the Virus Taxonomy 2015 released by International Committee on Taxonomy of Viruses (www.ictvonline.org/index.asp). Currently, the genus contains 35 known species including many agricultural important viruses, e.g., Potato virus X (PVX). Members of this genus are characterized by flexuous, filamentous virions of 13 nm in diameter and 470–580 nm in length. A potexvirus has a monopartite positive-strand RNA genome, encoding five open-reading frames (ORFs), with a cap structure at the 5′ end and a poly(A) tail at the 3′ end. Besides PVX, Bamboo mosaic virus (BaMV) is another potexvirus that has received intensive attention due to the wealth of knowledge on the molecular biology of the virus. In this review, we discuss the enzymatic activities associated with each of the functional domains of the BaMV replication protein, a 155-kDa polypeptide encoded by ORF1. The unique cap formation mechanism, which may be conserved across the alphavirus superfamily, is particularly addressed. The recently identified interactions between the replication protein and the plant host factors are also described.

Autophagy is involved in assisting the replication of Bamboo mosaic virus in Nicotiana benthamiana

“…Bamboo mosaic virus (BaMV) is a single-stranded positive-sense RNA virus belonging to Potexvirus of the family Alphaflexiviridae. The genome has five ORFs: ORF1 encodes the protein for viral RNA replication (Li et al , 1998, 2001a, 2001b; Huang et al , 2004; Meng and Lee, 2017); ORF2–ORF4 encode the proteins for cell-to-cell and systemic movement (Lin et al , 2004, 2006); and ORF5 encodes the capsid protein for encapsidation, symptom development, and viral movement (Lan et al , 2010; Hung et al , 2014a, 2014b). Host factors participating in the infection cycle of BaMV in N. benthamiana have been identified by using ultraviolet crosslinking (Lin et al , 2007; Prasanth et al , 2011; Huang et al , 2012), yeast two-hybrid (Lee et al , 2011), and cDNA-amplified fragment length polymorphism (Cheng et al , 2010) techniques.…”

Mitogen‐activated protein kinase phosphatase 1 reduces the replication efficiency of Bamboo mosaic virus in Nicotiana benthamiana

“…ORF1 directs the synthesis of the 155-kDa viral replication protein (REP BaMV ), principally responsible for transcription/replication of the viral genome and the synthesis of the 5' cap structure (Huang et al, 2005;Li et al, 1998Li et al, , 2001aLi et al, , 2001b. Organization of the functional domains and the domainassociated enzymatic activity of REP BaMV in terms of 5' cap formation and replication were summarized in a recent review (Meng and Lee, 2017). ORF2, 3 and 4 are overlapped, collectively referred to as triple gene block (TGB), and their translated proteins, TGBp1, TGBp2 and TGBp3, respectively, are essential for the virus movement in plants (Lin et al, 2004(Lin et al, , 2006.…”

Nuclear-Encoded Plastidal Carbonic Anhydrase Is Involved in Replication of Bamboo mosaic virus RNA in Nicotiana benthamiana

“…The genome comprises a 5′ cap structure, 3′ poly(A) tail, and five open reading frames (ORFs 1-5) ( Lin et al, 1994 ). ORF1, encoding a 155-kDa polypeptide, harbors three functional domains ( Meng and Lee, 2017 ): the capping enzyme domain, which exerts AdoMet-dependent guanylyltransferase activity ( Li et al, 2001a ; Huang et al, 2004 ; Hu et al, 2011 ); the helicase-like domain, which contains NTPase and RNA 5′-triphosphatase activities ( Li et al, 2001b ); and the RNA-dependent RNA polymerase (RdRp) core domain ( Li et al, 1998 ; Cheng et al, 2001 ). ORFs 2-4, encoding 28-, 13-, and 6-kDa polypeptides, respectively, overlap and are called triple-gene-block (TGB), designated TGBp1, -2, and -3, respectively.…”