Photodynamic therapy (PDT) applications are limited by the low penetration of UV−visible light into biological tissues. Considering Xrays as an alternative to excite photosensitizers (PS) in a deeper tumor, an intermediate particle able to convert the X-ray energy into visible light (scintillating nanoparticle, ScNP) is necessary. Moreover, accumulation of PS in the target cells is also required. Genetically encoded proteins could be used as a photosensitizer, allowing the exclusive expression of PS inside the tumor cells. Here, the interaction of eGFP, KillerOrange, and KillerRed proteins with LaF 3 :Tb 3+ ScNP was investigated, for the first time, in terms of its physicochemical and energy transfer properties. The protein structure, stability, and function were evaluated upon adverse physiological conditions and X-ray irradiation. Optimal parameters for energy transfer from ScNP to the proteins were investigated, paving the way for the use of genetically encoded photosensitizers for applications in X-ray activated photodynamic therapy.

Acyl-CoA Binding Proteins (ACBP) form a housekeeping family of proteins that is responsible for the buffering of long chain acyl-coenzyme A esters (LCFA-CoA) inside the cell. Even though numerous studies have focused on the characterization of different members of the ACBP family, the knowledge about the impact of both LCFA-CoA and phospholipids on ACBP structure and stability remains scarce. Besides, there are still controversies regarding the possible interaction of ACBP with biological membranes, even though this might be essential for the cargo capture and delivery. In this study, we observed that LCFA-CoA and phospholipids play opposite roles on protein stability and that the interaction with the membrane is dictated by electrostatic interaction. Furthermore, the results support the hypothesis that the LCFA-CoA delivery is driven by the increase of the negative charge on the membrane surface. The combined influence played by the different molecules on ACBP structure is discussed on the light of cargo capture/delivery giving new insights about this important process.

The Golgi complex is a membranous organelle located in the heart of the eukaryotic secretory pathway. A subfamily of the Golgi matrix proteins, called GRASPs, are key players in the stress-induced unconventional secretion, the Golgi dynamics during mitosis/apoptosis, and Golgi ribbon formation. The Golgi ribbon is vertebrate-specific and correlates with the appearance of two GRASP paralogs (GRASP55/GRASP65) and two coiled-coil Golgins (GM130/Golgin45), which interact with each other in vivo. Although essential for the Golgi ribbon formation and the increase in Golgi structural complexity, the molecular details leading to their appearance only in this subphylum are still unknown. Moreover, despite the new functionalities supported by the GRASP paralogy, little is known about the structural and evolutionary differences between these paralogues. In this context, we used ancestor sequence reconstruction and several biophysical/biochemical approaches to assess the evolution of the GRASP structure, flexibility, and how they started anchoring their Golgin partners. Our data showed that the Golgins appeared in evolution and were anchored by the single GRASP ancestor before gorasp gene duplication and divergence in Metazoans. After the gorasp divergence, variations inside the GRASP binding pocket determined which paralogue would recruit each Golgin partner (GRASP55 with Golgin45 and GRASP65 with GM130). These interactions are responsible for the protein's specific Golgi locations and the appearance of the Golgi ribbon. We also suggest that the capacity of GRASPs to form supramolecular structures is a long-standing feature, which likely affects GRASP's participation as a trigger of the stress-induced secretory pathway.

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