A few years ago I attended an ASM Branch meeting where an investigator gave a talk about a metagenomic survey of oceanic bacteriophages. In typical fashion for this type of study, one slide listed dozens genes of note identified as being encoded in phage genomes. With surprise I noticed that one of these was ftsZ, which encodes the prokaryotic tubulin homolog responsible for cell division in most bacteria and several phyla of archaea. I wondered: Why on Earth would a phage contain a cytoskeletal protein? The ftsZ gene is even found in chloroplasts and the mitochondria of certain protists, but at least these organelles have the evolutionary history of having been independent membrane-bound cells. But with a virus there is no ‘cyto’ in which to place any ‘skeleton’. An obvious hypothesis is that the phage might make use of a tubulin-like protein within the host for it nefarious phage reproduction cycle – but in what way?
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