Summary We report the first sensory rhodopsin observed in eubacterial domain, a green light‐activated photoreceptor Anabaena ( Nostoc ) sp. PCC7120, freshwater cyanobacterium. The gene encoding membrane opsin protein of 261 residues (26 kDa) and smaller soluble 125 (14 are under same promoter single operon. expressed heterologously Escherichia coli membranes bound all‐ trans retinal to form pink pigment (λmax 543 nm) with photochemical reaction cycle 110 ms half‐life (pH 6.8, 18°C)....

Microbial sensory rhodopsins are a family of membrane-embedded photoreceptors in prokaryotic and eukaryotic organisms. Structures archaeal rhodopsins, which function as light-driven ion pumps or photosensors, have been reported. We present the structure eubacterial rhodopsin, differs from those previously characterized its chromophore cytoplasmic-side portions. Anabaena rhodopsin exhibits light-induced interconversion between stable 13-cis all-trans states retinylidene protein. The ratio cis...

We characterize changes in isomeric states of the retinylidene chromophore during light-dark adaptation and photochemical reactions Anabaena (Nostoc) sp. PCC7120 sensory rhodopsin (ASR). The results show that ASR represents a new type microbial with number unusual characteristics. three most striking are: (i) primarily all-trans configuration retinal dark-adapted state (ii) 13-cis light-adapted blue-shifted lower extinction absorption spectrum, opposite case bacteriorhodopsin; (iii)...

Anabaena sensory rhodopsin (ASR) is a novel microbial recently discovered in the freshwater cyanobacterium sp. PCC7120. This protein most likely functions as photosensory receptor do related haloarchaeal rhodopsins. However, unlike archaeal pigments, which are tightly bound to their cognate membrane-embedded transducers, ASR interacts with soluble cytoplasmic analogous transducers of animal vertebrate In this study, infrared spectroscopy was used examine molecular mechanism photoactivation...

ABSTRACT Halophilic archaea, such as Halobacterium salinarum and Natronobacterium pharaonis , alter their swimming behavior by phototaxis responses to changes in light intensity color using visual pigment-like sensory rhodopsins (SRs). In N. SRII (NpSRII) mediates photorepellent through its transducer protein, NpHtrII. Here we report the expression of fusions NpSRII NpHtrII fusion hybrids with eubacterial cytoplasmic domains analyze function vivo haloarchaea eubacteria. A which C terminus is...

A number of peptides and peptide analogs derived from the membrane proximal region gp41 ectodomain are found to be effective inhibitors human immunodeficiency virus type 1 (HIV-1)-mediated fusion events. One them, T20 (aa 638–673), was disordered sparingly soluble in water, but became upon mixing with selected, structured amino terminal heptad repeat (HR1) using a simple sensitive method reduction scattering suspension. From results on mapping locus interaction by employing partially...

The conformation and interactions with membrane mimics of the NH2-terminal fragment 1–25 HA2, HA2-(1–25), influenza virus were studied by spectroscopic methods. Secondary structure analysis circular dichroism data revealed 45% helix for peptide at pH 5.0. Tryptophan fluorescence quenching acrylamide NMR experiments established that Trp14is inside vesicular interior residues 16–18 are micellar aqueous boundary. NBD enhancement labeled fluorophore on vesicle-bound indicated NH2 terminus fusion...

Refolding of denatured-reduced lysozyme and the effect co-refolding it with other proteins such as RNase A, bovine serum albumin, histone, myelin basic protein, alcohol dehydrogenase DNase I on renaturation yield aggregation have been studied. Basic consistently increase protein (10-20% more than in their absence) little or no aggregation. On hand, acidic leads to a significant decrease yields. Our results show that hetero-interchain interactions (non-specific interactions) occur when is...

Microorganisms encode proteins that function in the transformations of useful and harmful nitrogenous compounds global nitrogen cycle. The major cycle are fixation, nitrification, denitrification, anaerobic ammonium oxidation, ammonification. focus this report is complex biogeochemical process which, complete form, consists a series four enzyme-catalyzed reduction reactions transforms nitrate to gas. Denitrification microbial strain-level ecological trait (characteristic), denitrification...

A chimeric fusion protein consisting of Natronomonas pharaonis sensory rhodopsin II (SRII), fused by a flexible linker to the two transmembrane helices its cognate transducer protein, HtrII, followed HtrII membrane-proximal cytoplasmic fragment joined domains Escherichia coli chemotaxis receptor Tsr, was expressed in E. coli. Purified chimera reconstituted liposomes binds CheA kinase presence coupling CheW, and activates autophosphorylation activity. activity is stimulated photoexcitation...

Abstract Studies on the strength and extent of binding non-steroidal anti-inflammatory drug indomethacin to human serum albumin (HSA) have provided conflicting results. In present work, serum-binding was studied in 55 mM sodium phosphate buffer (pH 7·0) at 28°C, by using a fluorescence quench titration technique. The interaction with has been as function temperature, ionic pH. results suggest that electrostatic plays major role binding. possible lysine residues this modifying exposed buried...

Microorganisms convert sunlight into biological signals or energy using microbial rhodopsins via intricate mechanism. Vast family of such are categorized as ion pumps with established model bacteriorhodopsin, proteorhodopsin etc. Well studied sensory from archaea evident to mediate photo modulated response interaction their cognate transducer partner within the transmembrane. Such mechanism is quite distinct mammalian visual rhodopsins, which primarily involve activation membrane and relay...

3D structures of biomolecules are critical to understanding molecular mechanisms in core biological processes. Visualization these dynamic processes can be challenging for students. However, this skill is advancing their knowledge and reinforcing concepts beyond the textbook. Thus, protein structure–function relationships serve as a learning outcome many undergraduate biochemistry biology courses. The RCSB PDB database entries has grown over 200K past decade with an average increase about...

Abstract Protein structure–function relationship serves as the primary learning outcome in any undergraduate biochemistry course. We expanded protein exploration, PSFE initiative during COVID‐19 to provide more effective and engaging experience our undergraduates independent research courses. Multiple alignments of sequences provided crucial insight into sequence conservation across many species thus allow identification those sections most critical function. used Anabaena Sensory Rhodopsin,...

Abstract: A 43‐mer peptide derived from the coiled coil domain of transmembrane glycoprotein, gp41, human immunodeficiency virus type 1, was synthesized. Light scattering measurements suggested that molecules likely exist in aqueous solution trimeric form. Circular dichroism experiments showed a moderate helix population enhancement for 80% methanol relative to helicity sodium dodecyl sulfate micellar suspension. NMR spectroscopy indicated N‐terminal section conformationally more sensitive...

Anabaena sensory rhodopsin transducer, ASRT [125 amino acid sequence] is present under the same promoter of its rhodopsin, ASR in PCC 7120 a freshwater, filamentous, photosynthetic cynobacteria. The exists as tetrameric soluble protein indicated to function downstream signaling partner rhodopsin. Both solution and crystal structures has reveled that this primarily beta stranded exhibit helical face at carboxyl terminus. Besides receptor binding, been shown serve novel eukaryotic-like...