This week there are two fascinating stories in Nature Methods each giving us a glimpse of what structural biology might look like in a decade or so. Both papers describe a technical tour de force, shooting jets of micro crystals into the beam of a X-ray free electron laser and collecting X-ray diffraction images.
The first report utilizes recombinant protein (TbCatB) crystals that are grown in Sf9 insect cells. Yes, that's right: protein crystals grown in vivo, no crystallization setups necessary here.
Koopmann, R., Cupelli, K., Redecke, L., Nass, K., DePonte, D., White, T., Stellato, F., Rehders, D., Liang, M., Andreasson, J., Aquila, A., Bajt, S., Barthelmess, M., Barty, A., Bogan, M., Bostedt, C., Boutet, S., Bozek, J., Caleman, C., Coppola, N., Davidsson, J., Doak, R., Ekeberg, T., Epp, S., Erk, B., Fleckenstein, H., Foucar, L., Graafsma, H., Gumprecht, L., Hajdu, J., Hampton, C., Hartmann, A., Hartmann, R., Hauser, G., Hirsemann, H., Holl, P., Hunter, M., Kassemeyer, S., Kirian, R., Lomb, L., Maia, F., Kimmel, N., Martin, A., Messerschmidt, M., Reich, C., Rolles, D., Rudek, B., Rudenko, A., Schlichting, I., Schulz, J., Seibert, M., Shoeman, R., Sierra, R., Soltau, H., Stern, S., Strüder, L., Timneanu, N., Ullrich, J., Wang, X., Weidenspointner, G., Weierstall, U., Williams, G., Wunderer, C., Fromme, P., Spence, J., Stehle, T., Chapman, H., Betzel, C., & Duszenko, M. (2012). In vivo protein crystallization opens new routes in structural biology Nature Methods, 9 (3), 259-262 DOI: 10.1038/nmeth.1859
The second paper describes a similar experiment, carried out with small crystals of the Blastochloris viridis photosynthetic reaction center grown within lipidic phases. The resulting images actually resemble conventional X-ray diffraction images with proper Bragg spots, good enough to build a somewhat meager 8.2 Å resolution electron density map.
Johansson LC, Arnlund D, White TA, Katona G, Deponte DP, Weierstall U, Doak RB, Shoeman RL, Lomb L, Malmerberg E, Davidsson J, Nass K, Liang M, Andreasson J, Aquila A, Bajt S, Barthelmess M, Barty A, Bogan MJ, Bostedt C, Bozek JD, Caleman C, Coffee R, Coppola N, Ekeberg T, Epp SW, Erk B, Fleckenstein H, Foucar L, Graafsma H, Gumprecht L, Hajdu J, Hampton CY, Hartmann R, Hartmann A, Hauser G, Hirsemann H, Holl P, Hunter MS, Kassemeyer S, Kimmel N, Kirian RA, Maia FR, Marchesini S, Martin AV, Reich C, Rolles D, Rudek B, Rudenko A, Schlichting I, Schulz J, Seibert MM, Sierra RG, Soltau H, Starodub D, Stellato F, Stern S, Strüder L, Timneanu N, Ullrich J, Wahlgren WY, Wang X, Weidenspointner G, Wunderer C, Fromme P, Chapman HN, Spence JC, & Neutze R (2012). Lipidic phase membrane protein serial femtosecond crystallography. Nature methods PMID: 22286383
Granted, all of this is currently in the proof-of-concept stage - no actual high resolution structure determined yet - but this is how new exciting breakthrough technologies often start out. I'm wondering how long it will take for these technologies to mature to a state where they produce useful resolution structures and when they will become applicable to 'the rest of us'. Ten years, mid of the century maybe?
No protein crystallization setups, no crystal harvest, no cryo. X-FEL kills the crystallization champ.
This might change our game quite a bit.
Cheers,
Peter