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Samuels, E.

Publications and source records attributed to Samuels, E..

2 recordsLinked to original sources

A coelenterazine-dependent luciferase from the deep-sea coral Anthoptilum murrayi Kölliker, 1880 (Cnidaria: Octocorallia: Pennatulacea)

Bioluminescence is the production of visible light by living organisms through biochemical reactions in which specialized enzymes known as luciferases catalyze the oxidation of light-emitting substrates (luciferins), producing photons. In the ocean, bioluminescence is widespread among anthozoans (corals and sea anemones), yet the molecular basis of their light emission remains poorly defined. To date, molecular characterization within Anthozoa has largely focused on the sea pansy Renilla reniformis (Octocorallia: Renillidae), leaving anthozoan luciferase diversity underexplored. Here, we report the identification and biochemical characterization of a coelenterazine-dependent luciferase from the deepsea sea pen Anthoptilum murrayi (AnmLuc). Transcriptome analysis identified a transcript encoding a [~]34-kDa protein bearing motifs characteristic of coelenterazine-dependent luciferases. The coding sequence was cloned and the recombinant protein was expressed in Escherichia coli. The purified enzyme produced intense blue emission ({lambda}max {approx} 495 nm) in the presence of coelenterazine and displayed an activity optimum near 5 {degrees}C. These findings provide the first molecular characterization of a luciferase from a deep-sea anthozoan, expand the known diversity of coelenterazine-dependent luciferases in Cnidaria, and offer new insights into the mechanism and evolution of light emission in Anthozoa.

biochemistry↗

A putative ER-PM contact site complex relocalizes in response to Rare Earth Elements-induced endocytosis

In plant cells, environmental stressors induce changes in the cytosolic concentration of calcium ([Ca2+]cyt) that are transduced by Ca2+-sensing proteins. To confer specificity to the stress signaling response, [Ca2+]cyt sensing must be tightly regulated in space and time; the molecular mechanisms that restrict the localization and dynamics of Ca2+ sensors in plants, however, are largely unknown. In this report, we identify a putative Ca2+-sensitive complex containing the synaptotagmins 1 and 5 (SYT1 and SYT5) and the Ca2+-dependent lipid binding protein (CLB1), which is enriched at ER-PM contact sites (EPCS) and relocalizes in response to Rare Earth Elements (REEs)-induced endocytosis. Our results show that endocytosed REEs influence cytosolic Ca2+ signaling, as indicated by the activation of the Ca2+/Calmodulin-based ratiometric sensor GCaMP3, and promote the cytoskeleton-dependent accumulation of ER-PM contact sites at the cell cortex. Based on these results, we propose that the EPCS-localized SYT1/SYT5/CLB1 complex is part of an evolutionarily conserved and spatially regulated Ca2+-responsive mechanism that control cER-PM communication during stress episodes.

plant biology↗