Some time ago I posted breaking news about solved structure of usher pore. And few days ago it was deposited into PDB as 2VQI (publication appeared in Cell, here’s the abstract). The structure is a beatiful dimer (see above) of 24 stranded beta-barrel, the first of its kind. The paper contains also structures of the whole complex reconstructed based on cryo-EM data.
Interestingly, while the structure of the native dimer is symmetrical, the function of the units is not. Both of twinned pores are involved in alternating recruitment of chaperone:pili-subunit complexes, but only one actually transports pili subunits out. Overall, given large amount of detailed studies on the mechanistic properties of pili transport and formation, this is the best understood translocation process at a structural level.
Read the paper and draw your own conclusions, but for me it changes the way of thinking about protein translocation in bacteria. We learnt a lot on bacterial secretion by observing how similar proteins are involved in fundamentally different processes (for example DNA export and toxin secretion may use the same system). Similarly, usher pore is going to serve as an exemplar for newly found translocation elements.
Freelancing science 
Blogging overtaken by life streaming
I don’t post new things as often as I used to couple of months ago, but it’s not all my fault. FriendFeed and Google Reader (especially the newest feature of adding notes to shared things) create so much better space for rapid thoughts exchange than a blog, that I comment, link and share most of the things over there, and that includes even making scientific collaborations. This blog is going to loose a little of its dynamics, but already after few weeks I see advantages (like saving time) of moving micro-posts to World Wide Talk Show, as Robert Scoble calls FF.
Amount of interesting conversations at FF and Twitter combined is so huge that I don’t do random web browsing anymore (and I’m not the only one who says that). And I don’t even subscribe to thousands of people – it’s less than a hundred in total on both services. This list includes scientists (here’s probably already outdated list at Nature’s blog Nascent of scientist at FF), technologists and other interesting chaps.
So join us at Twitter or FriendFeed – my login at both services is “freesci”. Life is about interesting conversations, isn’t it? 🙂
UPDATE: Pierre Lindenbaum has obviously similar thoughts.
Posted by Pawel Szczesny on May 15, 2008 in Comments
Tags: FriendFeed, Google Reader, RSS, Twitter, World Wide Talk Show