Expression, Purification, Crystallization, and PAN-Cancer Analysis of the Human RNA 3'-terminal Phosphate Cyclase RTCA

RNA 3'-terminal phosphate cyclase (RTCA) is an enzyme that converts RNA 3'-terminal phosphate into an RNA 2',3'-cyclic phosphate terminus. RTCA regulates axon regeneration through the RNA repair and splicing pathway, as well as the production of ribosomal RNA and ribosome biogenesis. Although numerous biochemical studies have illuminated the function of human RTCA, the structure and how RTCA functions in various cancers remain to be elucidated. Here we expressed, purified, crystallized, and performed pan-cancer analysis of human RTCA. Combininig Ni-affinity chromatography with gel filter chromatography, high-purity RTCA protein was obtained. RTCA was crystallized utilizing the hanging drop vapor diffusion method. By preliminary X-ray diffraction analysis, it was shown that the resolution of the crystal was about 5 Å. In situ proteolytic analysis indicated that RTCA formed a compact structure in solution. Furthermore, our pan-cancer analysis revealed that RTCA is involved in the occurrence, poor prognosis, and development of various tumors, especially in lung cancer. Our pan-cancer analysis revealed that RTCA might act as a prognostic marker in lung cancer, and protein crystallization conditions provide a basis for RTCA protein structure elucidation.