by Andre on 21 February 2006
I’m in Salt Lake City at the Biophysical Society annual meeting this week and I just saw some great talks on single molecule mechanics. It’s time for a food break so I’ll take the chance to tell you a little bit about the conference so far.
After arriving on Friday evening and starting a sampling of Salt Lake brew pubs at Squatters (highly recommended), I attended the first talks of the conference yesterday. Rather than try to summarize everything (you can read the abstracts online for that), I’ll just highlight some of my favourites. One of them was by Hendrik Dietz from Matthias Rief’s lab whom I met last summer during my visit there. He showed that even though he hasn’t demonstrated the simultaneous fluorescence/atomic force microscope that he’s working on, he’s kept himself productively busy:
He talked about some recent work that they just published on engineered green fluorescent proteins that will polymerize into a long chain (via disulphide bonds between cysteine residues they added) appropriate for single molecule AFM pulling. One of the nice things about engineered proteins is that you can add the cysteines where you want and so they could pull the GFPs along several different axes instead of only the normal N- to C-terminus axis (see the figure for two examples). They found that there was a surprising array of stabilities along the different axes: the average unfolding forces ranged from the normal ~80 pN unfolding forces up to over 500 pN. I find this interesting from two points of view: as an expanded way to study protein structure and mechanics with AFM and as a tool to demonstrate the first simultaneous forced unfolding of proteins correlated with fluorescence changes.
Based on his talk I will now make the prediction that the first success in simultaneous fluorescence/force microscopy at the single molecule level will come from Hendrik since he now has a construct with lots of fluorescence, high unfolding forces, and a clear signature of unfolding in both fluorescence and force. There are still challenges, but it’s get closer all the time. Good luck Hendrik!