Envelope for an artificial cell
(糖心视频Org.com) -- Chemists have taken an important step in making artificial life forms from scratch. Using a novel chemical reaction, they have created self-assembling cell membranes, the structural envelopes that contain and support the reactions required for life.
Neal Devaraj, assistant professor of chemistry at the University of California, San Diego, and Itay Budin, a graduate student at Harvard University, report their success in the Journal of the American Chemical Society.
鈥淥ne of our long term, very ambitious goals is to try to make an artificial cell, a synthetic living unit from the bottom up 鈥� to make a living organism from non-living molecules that have never been through or touched a living organism,鈥� Devaraj said. 鈥淧resumably this occurred at some point in the past. Otherwise life wouldn鈥檛 exist.鈥�
By assembling an essential component of earthly life with no biological precursors, they hope to illuminate life鈥檚 origins.
鈥淲e don鈥檛 understand this really fundamental step in our existence, which is how non-living matter went to living matter,鈥� Devaraj said. 鈥淪o this is a really ripe area to try to understand what knowledge we lack about how that transition might have occurred. That could teach us a lot 鈥� even the basic chemical, biological principles that are necessary for life.鈥�
Molecules that make up cell membranes have heads that mix easily with water and tails that repel it. In water, they form a double layer with heads out and tails in, a barrier that sequesters the contents of the cell.
Devaraj and Budin created similar molecules with a novel reaction that joins two chains of lipids. Nature uses complex enzymes that are themselves embedded in membranes to accomplish this, making it hard to understand how the very first membranes came to be.
鈥淚n our system, we use a sort of primitive catalyst, a very simple metal ion,鈥� Devaraj said. 鈥淭he reaction itself is completely artificial. There鈥檚 no biological equivalent of this chemical reaction. This is how you could have a de novo formation of membranes.鈥�
They created the synthetic membranes from a watery emulsion of an oil and a detergent. Alone it鈥檚 stable. Add copper ions and sturdy vesicles and tubules begin to bud off the oil droplets. After 24 hours, the oil droplets are gone, 鈥渃onsumed鈥� by the self-assembling membranes.
Although other scientists recently announced the creation of a 鈥渟ynthetic cell,鈥� only its genome was artificial. The rest was a hijacked bacterial cell. Fully artificial life will require the union of both an information-carrying genome and a three-dimensional structure to house it.
The real value of this discovery might reside in its simplicity. From commercially available precursors, the scientists needed just one preparatory step to create each starting lipid chain.
鈥淚t鈥檚 trivial and can be done in a day,鈥� Devaraj said. 鈥淣ew people who join the lab can make membranes from day one.鈥�
Provided by University of California - San Diego
