Monthly Archives: April 2008

When I initially saw The MIT Registry of Standard Biological Parts, I just fell in love with the idea. However, after closer inspection I realized that it’s not what I hoped to find. The Registry collects an interchangeable functional modules that can be assembled into novel biological systems. And it does it as good as it sounds, but to a certain extent. Pedro wrote some time ago about unavoidable complexity and potential issues with collected parts. I completely agree with his arguments but I have even more doubts about the Registry’s current approach.

First of all, my feeling is that DNA-centric view of life starts to limit us in understanding what is happening at a molecular level. It moved forward science a lot and it is still extremely useful, but with genetics we are not going to understand and avoid emergent properties of biological systems. DNA, RNA, proteins at a sequence and structure level are all interacting with each other. This properties are encoded in DNA, I agree. However, as Pedro pointed out, we have no way to predict what happens after transferring a part to other organism. It is possible to select for mutations that will render this part usable in the other organism, but I don’t think this approach would be of much use if we deal with organisms that are hard to grow (imagine you want to insert a specific system into extremophile organism). And what is more, it’s not necessarily practical if we transfer the part to an organism which already has a similar element encoded in the genome.

In my humble opinion, the Registry can be extended in two directions, transforming parts into a containers that have a specific functional role and include sub-gene elements, like domains or tectons. Let me describe both in more detail.

Currently a BioBrick is assigned a function and a sequence. I would rather see a functional role, that can be fulfilled by many different sequences. For example, if we have an enzymatic function the BioBrick would include not only single DNA sequence from a single organism, but also a protein sequence, domains, sequence motifs and a structure (whatever is available), and all these should be available for all organisms for which we can assign reliably this information. To clarify, I’m far from populating the Registry with BLAST results. I would rather have it done manually, or at least in the way The SEED allows experts to create subsystems and assign a functional roles to proteins. In this way we could just take a gene from a target organism instead of mutating the original one. Having a container would mean that we could include there different flavors of the same gene (for example, after optimization).

For the second thing, I’m a big fan of creating novel functions out of existing elements. That’s a reason why I believe the Registry should include building blocks of proteins as well as other fancy things, like riboswitches. One of the obvious example would be a signal transduction element, where one can attach different receptor domains to the same membrane component. This has been done already thousands of times – why not to standardize it?

Maybe with these two changes maybe we could finally connects some dots and make a complexity of biological systems more understandable or at least traceable. Future directions of the Registry are not very well defined, so I believe there’s a space for at least discussion about such ideas.