Bacterial life has been pared to its genetic bare necessities in work led by scientist and entrepreneur Craig Venter, founder of the Craig Venter Institute in La Jolla, California.
The result is the cell JCVI-syn3.0, which thrives with a synthetic genome shorter than any in nature. Richard Kitney, co-director of the Centre for Synthetic Biology and Innovation at Imperial College, London, casts an independent eye over the research and looks at what it tells us and what it doesn’t.
What is the main advance from the creation of syn3.0?
What Venter’s team has done is to identify clear gaps in our knowledge about what makes a cell viable. They have essentially removed sections of the genome one by one to see what happens – in other words, to see if it dies and to try and understand why.
Does it take us closer towards the creation of living organisms from scratch?
This is not really a step forward in that sense.
What new insights has the bacterium syn3.0 given about life’s minimum requirements?
The failure of a predecessor bug with even fewer genes led to the refinement of genome design rules and identified a group of “indispensable” genes whose function now needs to be investigated.
What do you make of the fact that almost a third of the genes in syn3.0 have no known function, yet seem essential to life? What might they be doing?
This is partially because of the incomplete state of knowledge within the field. As Venter’s team also points out, the tools used to match genes in syn3.0’s genome to comparable ones with known functions in other organisms may have failed to identify some because their sequences differ too much. It is of course an intriguing question as to what any unidentified genes do.
Does the fact Venter borrowed the “shell” of a different organism as a host and provided a perfect environment for growth detract from his achievement?
Borrowing the shell of a naturally occurring bacterium is of course a major simplification of the technical challenge of making a synthetic organism – but it allowed the researchers to concentrate on the genome-minimisation problem, which is a very large endeavour on its own. Because of their choice of a rich growth medium, they could snip out many functions from the original host, because these are not needed when food is plentiful. What this all highlights is that there is in fact no universal minimal cell, only a minimal cell for a given set of conditions.
Does the work offer clues about how life began?
No, it tells us nothing about how life started naturally.
Where will this go next? Is it just a “vanity” project, or does it create useful avenues to pursue?
Venter and his colleagues are serious researchers pursuing an important goal, so this is absolutely not a vanity project. It is an important step towards meeting the need of synthetic biology for stable, well-understood host cells. What is, nevertheless, clear is that the host genome as presented has quite a way to go in terms of extending the catalogue of usable organisms available for synthetic biology.
Interview by Andy Coghlan
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