Your Weekly Dose of Proteins, September 25
Your Weekly Dose of Proteins
Frankly, I love proteins. Ever since I began exploring biology, I have been fascinated with these guys. In fact, I love proteins more than I love DNA. I think one of the reasons for this phenomenon is that proteins have an extreme variety in their 3D shapes, while DNA is pretty much the same ole’ double helix every time.
So, in honor of these hard-working proteins, I will have a new feature of this site: “Your Weekly Dose of Proteins,” where once a week I will show neat 3D renderings of proteins and explore proteins in general.
For our first weekly dose of proteins, I introduce you to a protein known as “YscJ.” YscJ is a component of the type III secretory system, and it forms an oligomeric ring complex, through which proteins are transported. What does ‘oligomer’ mean? This basically means that YscJ attaches to other YscJ monomers to form a complex that consists only of YscJ monomers.
YscJ is homologous to the flagellar component FliF, which also forms a ring structure.
The kewl thing about YscJ is the neat ring complex that it forms, beautifully illustrated by the below 3D models of the YscJ ring complex.
Top View: The YscJ ring complex. Each differently colored unit represents one YscJ monomer. Proteins are transported through the hole of the complex.
Side View: The YscJ ring complex. More than a couple dozen YscJ monomers are used to form the ring.
Of great interest to me is the question of how the origin flagellar FliF ring complex evolved by non-teleological processes. The YscJ ring complex could plausibly evolve from the flagellar ring complex – no new novelties would have to be introduced there – but how did the flagellar FliF ring complex evolve from a state where there was originally no FliF ring complex? Not only is there the problem of forming the first FliF protein, but there is the problem of how the FliF monomers were cobbled together to form the ring complex. The ring complex is made up of ~26 FliF monomers. Would 12 FliF monomers be of any use to a cell? These are questions to ponder in another post.
For now, let us enjoy the beauty of this world of proteins – a magnificence that transcends the debate over their origins.