Current Opinion in Microbiology
ISSN / EISSN : 1369-5274 / 1369-5274
Published by: Elsevier BV (10.1016)
Total articles ≅ 2,913
Latest articles in this journal
Current Opinion in Microbiology, Volume 61, pp 82-90; doi:10.1016/j.mib.2021.03.006
Upon first glance at a bacterial genome, pseudoenzymes appear unremarkable due to their lack of critical motifs that facilitate catalysis. These pseudoenzymes exist within signal transduction enzymes including histidine kinases, response regulators, diguanylate cyclases, and phosphodiesterases. Here, we summarize recent studies of bacterial pseudo-histidine kinases and pseudo-response regulators that regulate cell division, capsule formation, and the circadian rhythm. These examples illuminate the mechanistic potential of catalytically dead signaling enzymes and their impact upon bacterial signal transduction. Moreover, proteins lacking characteristic catalytic features of two-component systems reveal the sophisticated underlying potential of canonical two-component systems.
Current Opinion in Microbiology, Volume 61, pp 91-98; doi:10.1016/j.mib.2021.03.005
While bacteria typically lack membrane bound organelles, the mechanisms of subcellular organization have been unclear. Bacteria have recently been found to harbor membraneless organelles containing enzymes of many biochemical pathways. These organelles, called biomolecular condensates, have been found to commonly form through the process of liquid–liquid phase separation and are typically enriched in nucleic acid binding proteins. Interestingly, eukaryote and bacterial transcription and RNA decay machinery have been found to form biomolecular condensates. Additionally, DEAD Box ATPases from eukaryotes and bacteria have also been found to modulate biomolecular condensates. The shared ability of RNA metabolic enzymes to assemble into biomolecular condensates across domains suggests that this mode of subcellular organization aids in the control of RNA metabolism.
Current Opinion in Microbiology, Volume 61, pp 58-66; doi:10.1016/j.mib.2021.03.002
Carboxysomes are CO2-fixing protein compartments present in all cyanobacteria and some proteobacteria. These structures are attractive candidates for carbon assimilation bioengineering because they concentrate carbon, allowing the fixation reaction to occur near its maximum rate, and because they self-assemble in diverse organisms with a set of standard biological parts. Recent discoveries have expanded our understanding of how the carboxysome assembles, distributes itself, and sustains its metabolism. These studies have already led to substantial advances in engineering the carboxysome and carbon concentrating mechanism into recombinant organisms, with an eye towards establishing the system in industrial microbes and plants. Future studies may also consider the potential of in vitro carboxysomes for both discovery and applied science.
Current Opinion in Microbiology, Volume 61, pp 25-34; doi:10.1016/j.mib.2021.02.003
Bacterial lipoproteins are globular proteins anchored to a membrane by a lipid moiety. By discovering new functions carried out by lipoproteins, recent research has highlighted the crucial roles played by these proteins in the cell envelope of Gram-negative bacteria. Here, after discussing the wide range of activities carried out by lipoproteins in the model bacterium Escherichia coli, we review new insights into the essential mechanisms involved in lipoprotein maturation, sorting and targeting to their final destination. A special attention will also be given to the recent identification of lipoproteins on the surface of E. coli and of other bacteria. The renewed interest in lipoproteins is driven by the need to identify novel targets for antibiotic development.
Current Opinion in Microbiology, Volume 61, pp 8-15; doi:10.1016/j.mib.2021.01.004
PAS domains are widespread, versatile domains found in proteins from all kingdoms of life. The PAS fold is composed of an antiparallel β-sheet with several flanking α-helices, and contains a conserved cleft for cofactor or ligand binding. The last few years have seen a prodigious increase in identified PAS domains and resolved PAS structures, including structures with effector and other domains. New bacterial PAS ligands have been discovered, and structure-function studies have improved our understanding of PAS signaling mechanisms. The list of bacterial PAS functions has now expanded to include roles in signal sensing, modulation, transduction, dimerization, protein interaction, and cellular localization.
Current Opinion in Microbiology, Volume 61, pp 42-50; doi:10.1016/j.mib.2021.01.016
Chemosensory system is the most complex, specialized mode of signal transduction in bacteria and archaea. It is composed of several core and auxiliary protein components that are highly organized in order to deliver a fast response to changing environmental conditions. Chemosensory pathways were studied in-depth in a handful of model organisms and experimentally characterized at least to some degree in approximately thirty other species. However, genome-wide analyses have revealed their presence in thousands of sequenced microbial genomes. Both experimental and computational studies uncovered substantial diversity in system design, functional regulation, cellular localization and phyletic distribution of chemosensory pathways. Here, we summarize advances and expose gaps in our current understanding of the diversity of chemosensory systems.
Current Opinion in Microbiology, Volume 61, pp 124-132; doi:10.1016/j.mib.2021.04.002
Amphibian populations around the world have been affected by two pathogenic fungi within the phylum Chytridiomycota. Batrachochytrium dendrobatidis (Bd) has infected hundreds of species and led to widespread declines and some species extinctions. Batrachochytrium salamandrivorans (Bsal) has devastated some native European salamanders, especially the iconic fire salamanders (Salamandra salamandra). Comparative genomic studies show that Bd is more diverse and widespread than previously thought, and global lineages occur together allowing for the development of hybrid lineages. New studies raise the concern of greater pathogenesis if both Bd and Bsal infect the same host. Although amphibians possess robust immune defenses, co-infected and many single-infected hosts seem unable to mount effective immune responses. A strong defense may actually be harmful. Analysis of Bd and Bsal secretions documents small metabolites that signal high density to limit their growth and to suppress adaptive immune defenses, thus enabling a stealth presence in the skin compartment.
Current Opinion in Microbiology, Volume 61, pp 99-106; doi:10.1016/j.mib.2021.03.008
The Gram-negative bacterial cell envelope is a complex structure and its homeostasis is essential for bacterial survival. Envelope stress responses (ESRs) are signal transduction pathways that monitor the fidelity of envelope assembly during normal growth and also detect and repair envelope damage caused by external assaults, including immune factors, protein toxins, and antibiotics. In this review, we focus on three best-studied ESRs and discuss the mechanisms by which ESRs detect various perturbations of envelope assembly and integrity and regulate envelope remodeling to promote bacterial survival. We will highlight the complex relationship of ESRs with envelope biogenesis pathways and discuss some of the challenges in this field on the road to mapping the global regulatory network of envelope homeostasis.
Current Opinion in Microbiology, Volume 61; doi:10.1016/s1369-5274(21)00060-6
Current Opinion in Microbiology, Volume 61, pp 73-81; doi:10.1016/j.mib.2021.02.005
Bacteria use a wide variety of flagellar architectures to navigate their environment. While the iconic run-tumble motility strategy of the peritrichously flagellated Escherichia coli has been well studied, recent work has revealed a variety of new motility behaviors that can be achieved with different flagellar architectures, such as single, bundled, or opposing polar flagella. The recent discovery of various flagellar gymnastics such as flicking and flagellar wrapping is increasingly shifting the view from flagella as passive propellers to versatile appendages that can be used in a wide range of conformations. Here, we review recent observations of how flagella shape motility behaviors and summarize the nascent structure-function map linking flagellation and behavior.