TELSAM-target protein fusions can form diffraction-quality crystals without direct inter-polymer contacts
To better understand complicated biological systems, the protein structures associated with those systems must be determined. The historical approach in determining protein structures is protein crystallography, but traditional protein crystallization techniques are difficult and only successful in producing crystals 10-30% of the time. Polymer forming protein crystallization chaperones show promise in achieving crystallization on a range of target proteins. Crystallographers covalently attach target proteins to monomers of polymer forming proteins, increasing the likelihood of crystal formation due the highly ordered nature of polymer scaffolds. One example of a polymer forming protein crystallization chaperone is the TELSAM helical protein which previously achieved the crystallization of 10/11 target proteins. Unfortunately, many of the crystals obtained were too disordered to achieve a structural determination. In this presentation, we discuss work to solve the disorder problem in TELSAM derived crystals, which is achieved by altering the packing arrangement of target proteins. The goal is to test crystal formation, diffraction data, and multiple target proteins across a variety of engineered crystal lattice packing arrangements. We attained initial crystals with our 1TEL-CMG2 (TELSAM-CMG2) construct and determined the folded structure of the protein in the crystal lattice utilizing X-ray diffraction and modeling software. Due to the results of previous TELSAM-driven protein crystallization studies, we believed that 1TEL constructs would be incapable of forming highly ordered protein crystals. Thus, the crystal data we obtained transcends the current understanding of TELSAM-driven protein crystallization and has major implications on future applications of this form of protein crystallography. We are now working to publish our results and testing other TELSAM constructs with other target proteins to further increase our understanding of TELSAM-driven protein crystallization.