Intracellular microbial rhodopsin-based optogenetics to control metabolism and cell signaling.

Microbial rhodopsin (MRs) ion channels and pumps have become invaluable optogenetic tools for neuroscience as well as biomedical applications. Recently, MR-optogenetics expanded towards subcellular organelles opening principally new opportunities in optogenetic control of intracellular metabolism and signaling via precise manipulations of organelle ion gradients using light. This new optogenetic field expands the opportunities for basic and medical studies of cancer, cardiovascular, and metabolic disorders, providing more detailed and accurate control of cell physiology. This review summarizes recent advances in studies of the cellular metabolic processes and signaling mediated by optogenetic tools targeting mitochondria, endoplasmic reticulum (ER), lysosomes, and synaptic vesicles. Finally, we discuss perspectives of such an optogenetic approach in both fundamental and applied research.

Ferritin self-assembly, structure, function, and biotechnological applications.

Ferritin is a vital protein complex responsible for storing iron in almost all living organisms. It plays a crucial role in various metabolic pathways, inflammation processes, stress response, and pathogenesis of cancer and neurodegenerative diseases. In this review we discuss the role of ferritin in diseases, cellular iron regulation, its structural features, and its role in biotechnology. We also show that molecular mechanisms of ferritin self-assembly are key for a number of biotechnological and pharmaceutical applications. The assembly pathways strongly depend on the interface context of ferritin monomers and the stability of its different intermediate oligomers. To date, several schemes of self-assembly kinetics have been proposed. Here, we compare different self-assembly mechanisms and discuss the possibility of self-assembly control by switching between deadlock intermediate states.

Mirror proteorhodopsins.

Proteorhodopsins (PRs), bacterial light-driven outward proton pumps comprise the first discovered and largest family of rhodopsins, they play a significant role in life on the Earth. A big remaining mystery was that up-to-date there was no described bacterial rhodopsins pumping protons at acidic pH despite the fact that bacteria live in different pH environment. Here we describe conceptually new bacterial rhodopsins which are operating as outward proton pumps at acidic pH. A comprehensive function-structure study of a representative of a new clade of proton pumping rhodopsins which we name "mirror proteorhodopsins", from Sphingomonas paucimobilis (SpaR) shows cavity/gate architecture of the proton translocation pathway rather resembling channelrhodopsins than the known rhodopsin proton pumps. Another unique property of mirror proteorhodopsins is that proton pumping is inhibited by a millimolar concentration of zinc. We also show that mirror proteorhodopsins are extensively represented in opportunistic multidrug resistant human pathogens, plant growth-promoting and zinc solubilizing bacteria. They may be of optogenetic interest.