The Biology Refugia: House Too Small? - Overlapping Genes in Viruses - 0 views
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the longer the genome, the less gene overlap is present. They confirmed that this also held for DNA viruses. But when they grouped viruses by the kind of capsids they have–icosahedral vs. flexible–they found that this relationship is strong in the icosahedral capsid viruses, but weak in those with flexible capsids.
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icosahedral capsids are particularly rigid and constrained in size
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Even more outrageous is the notion that genes can overlap and still code for perfectly functional proteins, because this implies that, for part of the gene at least, a different reading frame still has functional meaning. This flies against our intuition that frame-shift mutations are the deadliest of all, and has been likened to taking a paragraph of text, moving all the spaces between words down by a character, and still being able to read it, but this time with a completely different meaning!
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Aha! This blog post (and the 2010 paper it cites) talks about evidence confirming my hunch about the plasticity of helical vs. icosahedral capsids with regard to genome size. The main focus of the paper is why viruses adopt overlapping genomes.
