21 articles
Acidic proteome of halophilic archaea
The acidic proteome of halophilic archaea is the proteome-wide shift toward aspartate- and glutamate-rich, hydrophobic-poor protein surfaces that lets proteins fold only in saturated salt.
Applied and engineered archaeal rhodopsins
Applied and engineered archaeal rhodopsins are uses of bacteriorhodopsin, a light-driven proton pump from the archaeon Halobacterium salinarum, as active materials in holographic storage, photocells, and biosensors.
Archaeal rhodopsin photochemistry and photocycle
Archaeal rhodopsin photochemistry and photocycle cover how light isomerizes retinal bound to a Schiff base, driving ion pumping through intermediates J through O in bacteriorhodopsin and related pigments.
Archaerhodopsin
Archaerhodopsin (Arch, AR3) is a family of light-driven proton-pumping retinal proteins from halophilic archaea, discovered 1988 in Australian Halobacterium; Arch from Halorubrum sodomense is the basis of fluorescent voltage indicators like QuasAr and Archon.
Betaine transporter
Betaine transporter: membrane proteins (BCCT family, ABC types such as OpuA/OpuD/BetP/Ota, and mammalian BGT1) that import glycine betaine as an osmoprotectant in bacteria, archaea, and mammals.
Compatible-solute biosynthesis in halophiles
Compatible-solute biosynthesis is how halophilic and halotolerant microbes make organic osmolytes like glycine betaine and ectoine to balance osmotic pressure instead of using the salt-in strategy.
Compatible-solute uptake and transport in halophilic archaea
Compatible-solute uptake and transport in halophilic archaea is the membrane transport by which salt-loving archaea import protective molecules like glycine betaine and ectoine, mostly through sodium-coupled symporters.
Ectoine
Ectoine, a zwitterionic tetrahydropyrimidine compatible solute discovered in 1985 in Ectothiorhodospira halochloris, protects microbes against osmotic, heat, cold, and desiccation stress; produced industrially and used in atopic dermatitis creams and cryopreservation.
Experimental systems and methods for archaeal rhodopsins
Experimental systems for archaeal rhodopsins center on Halobacterium salinarum and Natronomonas pharaonis, transformed by PEG-mediated spheroplast methods and studied through flash photolysis spectroscopy and in meso crystallography of bacteriorhodopsin.
Halobacterium salinarum
Halobacterium salinarum, formerly H. halobium and H. cutirubrum, is an extremely halophilic archaeon from salted fish and salterns, model organism for bacteriorhodopsin, halorhodopsin, and sensory rhodopsins, with the first sequenced haloarchaeal genome (NRC-1).
Halophile
Halophile: salt-loving microorganism requiring or tolerating high NaCl, found across Archaea, Bacteria, and Eukarya; classified slight, moderate, or extreme; uses salt-in or salt-out osmoadaptation; industrially valued for halozymes and bioplastics.
Halorhodopsin
Halorhodopsin (HR), a microbial rhodopsin chloride pump, uses light-absorbing retinal to pump chloride into cells; Natronomonas pharaonis HR (590 nm) is the optogenetic neural silencer, distinct from proton-pumping bacteriorhodopsin.
Mechanosensitive channels
Mechanosensitive channels are membrane proteins that convert mechanical force into ion flow. Key families: bacterial MscL/MscS osmotic safety valves and mammalian Piezo1/2 touch channels, recognized by the 2021 Nobel Prize.
Osmotic physiology in hypersaline niches
Osmotic physiology in hypersaline niches is the study of how microorganisms balance water across cell membranes in brines too salty for most life, spanning the salt-in and salt-out strategies.
Phototrophic energy metabolism in haloarchaea
Phototrophic energy metabolism in haloarchaea is a non-chlorophyll photosynthesis in which retinal-based pumps like bacteriorhodopsin generate a proton motive force that drives ATP synthesis in salt-loving archaea.
Purple membrane
The purple membrane is a patch of the archaeon Halobacterium salinarum's cytoplasmic membrane in which bacteriorhodopsin, a light-driven proton pump, is packed into a two-dimensional crystalline lattice; it was isolated in 1971.
Rhodopsin phototrophy in hypersaline ecosystems
Rhodopsin phototrophy in hypersaline ecosystems is light capture by retinal-pumping microbes such as haloarchaea and Salinibacter, whose ion pumps rival or surpass photosynthesis in salt-saturated saltern brines.
Salt-dependent enzyme folding in halophilic archaea
Salt-dependent enzyme folding is the requirement of enzymes from extremely halophilic archaea for molar salt, usually KCl, to fold and stay folded; without it, many proteins unfold.
Salt-in strategy
The salt-in strategy is an osmoadaptation used by haloarchaea, and convergently by the bacterium Salinibacter ruber, which accumulate molar intracellular KCl instead of organic solutes.
Sensory rhodopsins and phototaxis in haloarchaea
Sensory rhodopsins are retinal-containing light receptors in haloarchaea that steer phototaxis. In Halobacterium salinarum, SRI attracts cells to orange light while SRII triggers avoidance of blue light.
Small-conductance mechanosensitive channel
MscS, the small-conductance mechanosensitive channel of E. coli, is a heptameric ~1 nS tension-gated bacterial emergency release valve protecting cells from hypoosmotic shock, founding member of the MscS-like superfamily.