RESUMEN
Reflectin proteins are natural copolymers consisting of repeated canonical domains. They are located in a biophotonic system called Bragg lamellae and manipulate the dynamic structural coloration of iridocytes. Their biological functions are intriguing, but the underlying mechanism is not fully understood. Reflectin A1, A2, B1, and C were found to present distinguished cyto-/nucleoplasmic localization preferences in the work. Comparable intracellular localization was reproduced by truncated reflectin variants, suggesting a conceivable evolutionary order among reflectin proteins. The size-dependent access of reflectin variants into the nucleus demonstrated a potential model of how reflectins get into Bragg lamellae. Moreover, RfA1 was found to extensively interact with the cytoskeleton, including its binding to actin and enrichment at the microtubule organizing center. This implied that the cytoskeleton system plays a fundamental role during the organization and transportation of reflectin proteins. The findings presented here provide evidence to get an in-depth insight into the evolutionary processes and working mechanisms of reflectins, as well as novel molecular tools to achieve tunable intracellular transportation.
RESUMEN
Amyloid beta (Aß) aggregation and oxidative stress are two of the central events in Alzheimer's Disease (AD). Both these phenomena can be caused by the interaction of Aß with metal ions. In the last years the interaction between ZnII , CuII , and Aß was much studied, but between iron and Aß it is still little known. In this work we determine how three Aß peptides, present in AD, interact with FeIII -citrate. The three Aß peptides are: full length Aß1-42, an isoform truncated at Glutamic acid in position three, Aß3-42, and its pyroglutamated form AßpE3-42. Conformation and morphology of the three peptides, aggregated with and without FeIII -citrate were studied. Besides, we have determined the strength of the interactions Aß/FeIII -citrate studying the effect of ethylenediaminetetraacetic acid as chelator. Results reported here demonstrate that FeIII -citrate promotes the aggregation in all the three peptides. Moreover, Aspartic acid 1, Glutamic acid 3, and Tyrosine 10 have an important role in the coordination with iron, generating a more stable complex for Aß1-42 compared to that for the truncated peptides.