GSE96573
Reduced protein expression in a virus attenuated by codon deoptimization
A general means of viral attenuation involves the extensive recoding of synonymous codons in the viral  genome. The mechanistic underpinnings of this approach remain unclear, however. Using quantitative  proteomics and RNA sequencing, we explore the molecular basis of attenuation in a strain of bacteriophage  T7 whose major capsid gene was engineered to carry 182 suboptimal codons. We do not detect  transcriptional effects from recoding. Proteomic observations reveal that translation is halved for the recoded  major capsid gene, and a more modest reduction applies to several co-expressed downstream genes.  We observe no changes in protein abundances of other co-expressed genes that are encoded upstream.  Viral burst size, like capsid protein abundance, is also decreased by half. Together, these observations  suggest that, in this virus, reduced translation of an essential polycistronic transcript and diminished  virion assembly form the molecular basis of attenuation. Overall design: mRNA profiles of T7-infected E. coli from three different strains of T7, across three distinct time points post-infection, with three replicates of each strain-time combination.