Disease relevance of BMVs1gp1

• Using an RNA-dependent RNA polymerase (replicase) preparation from barley leaves infected with brome mosaic virus (BMV) to synthesize the viral subgenomic RNA in vitro, we now provide evidence that subgenomic RNA arises by internal initiation on the (-)-strand of genomic RNA [1].
• We believe that this also represents the first in vitro demonstration of a replicase from a eukaryotic (+)-stranded RNA virus capable of initiating synthesis of (+)-sense RNA [1].
• An RNA-dependent RNA polymerase (replicase) extract from brome mosaic virus-infected barley leaves has been shown to initiate synthesis of (-) sense RNA from (+) sense virion RNA [2].
• Each deletion strain was transformed to express BMV replicase proteins and a BMV RNA replication template with the capsid gene replaced by a luciferase reporter [3].
• Recent studies have shown that disrupted (open) rotavirus cores have an associated replicase activity which supports the synthesis of dsRNA from viral mRNA in a cell-free system (D. Chen, C. Q.-Y. Zeng, M. J. Wentz, M. Gorziglia, M. K. Estes, and R. F. Ramig, J. Virol. 68:7030-7039, 1994) [4].

High impact information on BMVs1gp1

• Mutant viral RNAs synthesized in vitro show altered aminoacylation and replicase template activities [5].
• An RNA3 mutant bearing a 20-base deletion yielding normal levels of aminoacylation and enhanced levels of replicase template activity and adenylation in vitro was able to replicate in protoplasts and plants; however, its accumulation in protoplasts was reduced relative to wild-type [6].
• Identification of sequences in Brome mosaic virus replicase protein 1a that mediate association with endoplasmic reticulum membranes [7].
• In contrast, we find that position-specific changes in the RNA sequence will affect replicase recognition, modulate the polymerization process, and contribute to the differential accumulation of viral RNAs [8].
• Sequencing using cordycepin triphosphate to terminate (-) strands during their synthesis by the replicase generated sequence ladders that confirmed that copying was accurate, and that initiation occurred very close to the 3' end [2].

Chemical compound and disease context of BMVs1gp1

• Additional experiments involving coinoculation of either C3/DeltaCP-EGFP or C3/CP:EGFP with heterologous brome mosaic bromovirus (BMV) genomic RNAs 1 and 2 revealed that, in addition to movement protein and CP, viral replicase also influences cell-to-cell spread [9].

Biological context of BMVs1gp1

• By native gel electrophoresis, enzymatic structure probing, and NMR spectroscopy it is shown here that in the absence of viral replicase the hexanucleotide loop 5'C1AUAG5A3' of this RNA structure can adopt a pseudo trinucleotide loop conformation by transloop base pairing between C1 and G5 [10].
• Several sequences encoding functions, including replicase binding, initiation of (-) strand synthesis and tyrosine esterification are known to be nested within this region [11].

Anatomical context of BMVs1gp1

• Brome mosaic virus replicase proteins localize with the movement protein at infection-specific cytoplasmic inclusions in infected barley leaf cells [12].

Associations of BMVs1gp1 with chemical compounds

• Biochemical studies of the 5'AUG3' loop with various substitutions in the context of the whole SLC construct confirm that the clamped adenine motif exists in S-AUG remains a primary structural feature required for RNA synthesis by the BMV replicase [13].

Analytical, diagnostic and therapeutic context of BMVs1gp1

• Subcellular localization of the Brome mosaic virus replicase-related 1a and 2a proteins, and the 3a movement protein in infected barley leaves was examined by immunogold electron microscopy [12].

References