Abstract
Replication of plus-strand RNA viruses depends on host factors that are recruited into viral replicase complexes. Previous studies showed that eukaryotic translation elongation factor (eEF1A) is one of the resident host proteins in the highly purified tombusvirus replicase complex. Using a random library of eEF1A mutants, we identified one mutant that decreased and three mutants that increased Tomato bushy stunt virus (TBSV) replication in a yeast model host. Additional in vitro assays with whole cell extracts prepared from yeast strains expressing the eEF1A mutants demonstrated several functions for eEF1A in TBSV replication: facilitating the recruitment of the viral RNA template into the replicase complex; the assembly of the viral replicase complex; and enhancement of the minus-strand synthesis by promoting the initiation step. These roles for eEF1A are separate from its canonical role in host and viral protein translation, emphasizing critical functions for this abundant cellular protein during TBSV replication.
Highlights
Genome-wide screens for host factors affecting RNA virus infections have led to the identification of several hundreds host proteins in recent years [1,2,3,4,5,6,7]
We show that the eukaryotic translation elongation factor, which is one of the resident host proteins in the highly purified tombusvirus replicase complex, is important for Tomato bushy stunt virus (TBSV) replication in a yeast model host
In vitro studies revealed that eukaryotic translation elongation factor 1A (eEF1A) facilitated the recruitment of the viral RNA template for replication and the assembly of the viral replicase complex, as well as eEF1A enhanced viral RNA synthesis in vitro
Summary
Genome-wide screens for host factors affecting RNA virus infections have led to the identification of several hundreds host proteins in recent years [1,2,3,4,5,6,7]. These works demonstrated complex interactions between the host and plus-stranded (+)RNA viruses, the largest group among viruses. (+)RNA viruses contain relatively small genomes and greatly depend on the resources of the infected hosts in many steps during the infection process These viruses recruit numerous host proteins to facilitate their replication and spread [8,9,10]. The viral RNA participates in RNA recombination [6,18,24], which likely plays a major role in virus evolution
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