Calmodulin Enhances Cryptochrome Binding to INAD in Drosophila Photoreceptors.

Light is the main environmental stimulus that synchronizes the endogenous timekeeping systems in most terrestrial organisms. Drosophila cryptochrome (dCRY) is a light-responsive flavoprotein that detects changes in light intensity and wavelength around dawn and dusk. We have previously shown that dCRY acts through Inactivation No Afterpotential D (INAD) in a light-dependent manner on the Signalplex, a multiprotein complex that includes visual-signaling molecules, suggesting a role for dCRY in fly vision. Here, we predict and demonstrate a novel Ca2+-dependent interaction between dCRY and calmodulin (CaM). Through yeast two hybrid, coimmunoprecipitation (Co-IP), nuclear magnetic resonance (NMR) and calorimetric analyses we were able to identify and characterize a CaM binding motif in the dCRY C-terminus. Similarly, we also detailed the CaM binding site of the scaffold protein INAD and demonstrated that CaM bridges dCRY and INAD to form a ternary complex in vivo. Our results suggest a process whereby a rapid dCRY light response stimulates an interaction with INAD, which can be further consolidated by a novel mechanism regulated by CaM.

1H, 13C and 15N resonance assignment of the cytosolic dithiol glutaredoxin 1 from the pathogen Trypanosoma brucei.

Trypanosomatids are parasites responsible for several tropical and subtropical diseases, such as Chaga's disease, sleeping sickness and Leishmaniasis. In contrast to the mammalian host, the thiol-redox metabolism of these pathogens depends on trypanothione [bis-glutathionylspermidine, T(SH)2] instead of glutathione (GSH) providing a set of lineage-specific proteins as drug target candidates. Glutaredoxins (Grx) are ubiquitous small thiol-disulfide oxidoreductases that belong to the thioredoxin-fold family. They play a central role in redox homeostasis and iron sulfur-cluster biogenesis. Each species, including trypanosomes, possesses its own set of isoforms distributed in different subcellular compartments. The genome of trypanosomatids encodes for two class I (dithiolic) Grxs named 2-C-Grx1 and 2-C-Grx2. Both proteins were shown to efficiently reduce different disulfides at the expenses of T(SH)2 using a mechanism that involves the two cysteines in the active site. Moreover, the cytosolic Trypanosoma brucei 2-C-Grx1 but not the mitochondrial 2-C-Grx2 was able to coordinate an iron-sulfur cluster with T(SH)2 or GSH as ligand. As a first step to unravel the structural basis for the specificity observed in the trypanosomal glutaredoxins, we present here the NMR resonance assignment of 2-C-Grx1 from the parasite T. brucei brucei.

[Cluster of malignant mesothelioma cases in a thermostat manufacturing industry]. / Cluster di casi di mesotelioma maligno in una azienda produttrice di termostati.

BACKGROUND: Malignant mesothelioma is a rare disease and the identification of a cluster of cases suggests a possible presence of an asbestos contamination source. OBJECTIVES: To describe 3 cases of malignant mesothelioma (2 pleural and 1 peritoneal) that occurred in workers employed in the same thermostat factory. METHODS: Since this occupational sector is not traditionally known for asbestos exposure the Lombardy Mesothelioma Registry proposed to Local Occupational Health Unit to investigate this industry. RESULTS: From the first inspection of the plant, an environmental asbestos contamination (ropes covering oven handle and gasket) was found. But the greatest source of exposure was identified in the melamine resin reinforced with asbestos that constituted some internal parts of thermostats and that were sheared and perforated by the workers. So the 3 cases were defined as occupational diseases and legal procedures were initiated. CONCLUSION: The results underline the importance of a close cooperation within Local Occupational Health Units and Mesothelioma Registry in the identification and evaluation of asbestos occupational exposure otherwise not recognized, determining thus the loss of precious information.