Scientists have taken another step in their quest to understand the bare genetic essentials of life.A team led by US research entrepreneur Craig Venter has created a semi-synthetic, functioning bacterium in the lab that has fewer than 500 genes.This minimal number is lower than in any known free-living bug in nature.The group says its investigations aim to push the boundaries of fundamental knowledge and could lead to novel means to make new drugs and other chemicals.”Our long-term vision has been to design and build synthetic organisms on demand where you can add in specific functions and predict what the outcome is going to be,” said Daniel Gibson, who is a co-author on a paper describing the latest work in Science Magazine.”We think these cells would be a very useful chassis for many industrial applications, from medicine to biochemicals, biofuels, nutrition and agriculture,” he told reporters.The team reported its first semi-synthetic organism in 2010.
In that project, the scientists constructed in the lab the entire “genetic software” of Mycoplasma mycoides, a microbe that lives in cattle and other ruminants.This artificial package of DNA was then transplanted into the cell of another Mycoplasma species that had been emptied of its genome, and “booted up”. The engineered bug, dubbed Syn 1.0, duly started to divide.In the new paper, Dr Venter and his colleagues report how they have now reduced the biochemical instructions in this organism to the bare minimum.After a long series of trial and error experiments, the Mycoplasma microbe, now dubbed Syn 3.0, can operate on just 473 genes – about half the number found in the wild bug, and about 50 fewer than in the related Mycoplasma genitalium, which has the smallest set of genes in any independent organism known to science.By way of comparison, more complex organisms such plants and animals can have many tens of thousands of genes driving their biology.Dr Venter and colleagues have been pursuing the idea of a minimal genome for 20 years. Their earlier studies suggested the rock-bottom number could be around 300. But in pinning down Sin 3.0’s must-haves, the California-based scientists have found that the real number is higher.
source: Jonathan Amos (BBC)
