Photoactive Yellow Protein Represents a Distinct, Evolutionarily Novel Family of PAS Domains

Light Control in Microbial Systems

Light is a key environmental component influencing many biological processes, particularly in prokaryotes such as archaea and bacteria. Light control techniques have revolutionized precise manipulation at molecular and cellular levels in recent years. Bacteria, with adaptability and genetic tractability, are promising candidates for light control studies. This review investigates the mechanisms underlying light activation in bacteria and discusses recent advancements focusing on light control methods and techniques for controlling bacteria. We delve into the mechanisms by which bacteria sense and transduce light signals, including engineered photoreceptors and light-sensitive actuators, and various strategies employed to modulate gene expression, protein function, and bacterial motility. Furthermore, we highlight recent developments in light-integrated methods of controlling microbial responses, such as upconversion nanoparticles and optical tweezers, which can enhance the spatial and temporal control of bacteria and open new horizons for biomedical applications.

Multifaceted photoreceptor compositions in dual phototrophic systems - A genomic analysis

For microbes and their hosts, sensing of external cues is essential for their survival. For example, in the case of plant associated microbes, the light absorbing pigment composition of the plant as well as the ambient light conditions determine the well-being of the microbe. In addition to light sensing, some microbes can utilize xanthorhodopsin based proton pumps and bacterial photosynthetic complexes that work in parallel for energy production. They are called dual phototrophic systems. Light sensing requirements in these type of systems are obviously demanding. In nature, the photosensing machinery follows mainly the same composition in all organisms. However, the specific role of each photosensor in specific light conditions is elusive. In this study, we provide an overall picture of photosensors present in dual phototrophic systems. We compare the genomes of the photosensor proteins from dual phototrophs to those from similar microbes with "single" phototrophicity or microbes without phototrophicity. We find that the dual phototrophic bacteria obtain a larger variety of photosensors than their light inactive counterparts. Their rich domain composition and functional repertoire remains similar across all microbial photosensors. Our study calls further investigations of this particular group of bacteria. This includes protein specific biophysical characterization in vitro, microbiological studies, as well as clarification of the ecological meaning of their host microbial interactions.

MiST 4.0: a new release of the microbial signal transduction database, now with a metagenomic component

Signal transduction systems in bacteria and archaea link environmental stimuli to specific adaptive cellular responses. They control gene expression, motility, biofilm formation, development and other processes that are vital to survival. The microbial signal transduction (MiST) database is an online resource that stores tens of thousands of genomes and allows users to explore their signal transduction profiles, analyze genomes in bulk using the database application programming interface (API) and make testable hypotheses about the functions of newly identified signaling systems. However, signal transduction in metagenomes remained completely unexplored. To lay the foundation for research in metagenomic signal transduction, we have prepared a new release of the MiST database, MiST 4.0, which features over 10 000 metagenome-assembled genomes (MAGs), a scaled representation of proteins and detailed BioSample information. In addition, several thousands of new genomes have been processed and stored in the database. A new interface has been developed that allows users to seamlessly switch between genomes and MAGs. MiST 4.0 is freely available at https://mistdb.com; metagenomes and MAGs can also be explored using the API available on the same page.

Current Trends of Bacterial and Fungal Optoproteins for Novel Optical Applications

Photoproteins, luminescent proteins or optoproteins are a kind of light-response protein responsible for the conversion of light into biochemical energy that is used by some bacteria or fungi to regulate specific biological processes. Within these specific proteins, there are groups such as the photoreceptors that respond to a given light wavelength and generate reactions susceptible to being used for the development of high-novel applications, such as the optocontrol of metabolic pathways. Photoswitchable proteins play important roles during the development of new materials due to their capacity to change their conformational structure by providing/eliminating a specific light stimulus. Additionally, there are bioluminescent proteins that produce light during a heatless chemical reaction and are useful to be employed as biomarkers in several fields such as imaging, cell biology, disease tracking and pollutant detection. The classification of these optoproteins from bacteria and fungi as photoreceptors or photoresponse elements according to the excitation-emission spectrum (UV-Vis-IR), as well as their potential use in novel applications, is addressed in this article by providing a structured scheme for this broad area of knowledge.

Origin and functional diversification of PAS domain, a ubiquitous intracellular sensor

Signal perception is a key function in regulating biological activities and adapting to changing environments. Per-Arnt-Sim (PAS) domains are ubiquitous sensors found in diverse receptors in bacteria, archaea, and eukaryotes, but their origins, distribution across the tree of life, and extent of their functional diversity are not fully characterized. Here, we show that using sequence conservation and structural information, it is possible to propose specific and potential functions for a large portion of nearly 3 million PAS domains. Our analysis suggests that PAS domains originated in bacteria and were horizontally transferred to archaea and eukaryotes. We reveal that gas sensing via a heme cofactor evolved independently in several lineages, whereas redox and light sensing via flavin adenine dinucleotide and flavin mononucleotide cofactors have the same origin. The close relatedness of human PAS domains to those in bacteria provides an opportunity for drug design by exploring potential natural ligands and cofactors for bacterial homologs.