Early Evolution Of Life Research Articles

Nutritional programming of large yellow croaker (Larimichthys crocea) larvae by dietary vegetable oil: effects on growth performance, lipid metabolism and antioxidant capacity.

The nutritional status experienced in the early development of life plays a vital role in the long-term metabolic state of the individual, which is known as nutritional programming. The present study investigated the long-term effects of vegetable oil (VO) nutritional programming during the early life of large yellow croaker. First, larvae were fed either a fish oil (FO) diet or a VO diet for 30 d. Subsequently, under the same conditions, all fish were fed a commercial diet for 90 d and thereafter challenged with an FO or VO diet for 30 d. The results showed that growth performance was significantly lower in larvae fed the VO diet than in those in fed the FO diet in the stimulus phase. Notably, VO nutritional history fish showed lower levels of liver lipids liver total triglycerides and serum nonesterified free fatty acids than the FO nutritional history fish when juveniles were challenged with the VO diet, which was consistent with the expression of lipogenesis-related genes and proteins. Moreover, the VO nutritional history fish showed lower liver damage and higher antioxidant capacity than FO nutritional history fish when challenged with the VO diet. In summary, this study showed that a short VO stimulus during the early life stage of large yellow croaker, had a long-term effect on lipid metabolism and the antioxidant system. Specifically, VO nutritional programming had a positive effect on alleviating abnormal lipid deposition on the liver, liver damage, and the reduction of hepatic antioxidant capacity caused by a VO diet.

A Neoarchean (ca. 2500 Ma) age for jaspilite-carbonate BIF hosting purported micro-fossils from the Eoarchean (≥3750 Ma) Nuvvuagittuq supracrustal belt (Québec, Canada)

In the exploration of the origin and evolution of early life on Earth, age determinations of fossil occurrences are of critical importance. Purported microbial fossils preserved in chert and jasper are commonly assigned indirect dates due to a lack of suitable minerals for geochronology in the fossil-bearing horizons. Such indirect dating methods commonly result in age estimates that predate the hosted putative fossil structures, especially when considering possible formation of these structures in post-depositional hydrothermal/metamorphic events. Herein, we report a Neoarchean (ca. 2.5 Ga) U-Pb ID-TIMS zircon and apatite age for jaspilite and carbonate-bearing iron formation that hosts putative ferruginous “microbial fossil structures” in the Eoarchean Nuvvuagittuq supracrustal belt (NSB) in northern Québec (Canada). In situ oxygen isotope and REE compositions suggest apatite and calcite separated from jaspilite are hydrothermal in origin. Collectively, our results suggest that some of these ferruginous “microbial fossil structures” could be primary biogenic structures produced in an Eoarchean hydrothermal environment that survived subsequent late Archean metamorphism and deformation. In contrast, some are possibly abiogenic structures formed via Liesegang-type processes during late Archean hydrothermal activity. A broader assessment of the ages of putative biostructures in Eoarchean and Paleoarchean rocks, wherein incorrect age assignment remains a persistent problem, is therefore warranted.

Meteorites: beneficial or toxic for life on Early Earth? Growth of an anaerobic microbial community on a carbonaceous chondrite

Meteoritic material accumulated on the surface of the anoxic Early Earth during the Late Heavy Bombardment around 4.0 Gya. These meteorites may have provided the Earth with extra-terrestrial nutrients and energy sources for early life. How could the presence of meteorites have affected the origin and evolution of early life on Earth? And what is the influence of geothermal activity on the Earth’s surface? This research investigates the growth of an anaerobic microbial community from pond sediment on non-pyrolyzed (pristine) or pyrolyzed (heat-treated) carbonaceous chondrite ‘Cold Bokkeveld’. A microbial community was grown anaerobically in batch cultures containing a liquid environment and powdered non-pyrolyzed or pyrolyzed Cold Bokkeveld. Cell concentrations were measured by Colony-Forming Units on agar plates. The community composition in the presence of non-pyrolyzed meteorite was determined by 16S rRNA amplicon sequencing. Non-pyrolyzed Cold Bokkeveld supported the growth of a stable, anaerobic community containing mainly the Deltaproteobacteria Geobacteraceae and Desulfuromonadaceae. Members of these families are known to use elemental sulfur and ferric iron as electron acceptors, and organic compounds as electron donors. Pyrolyzed Cold Bokkeveld however, was inhibitory to the growth of the microbial community. These results show that carbonaceous chondrites can host an anaerobic microbial community, but that pyrolysis, e.g. by geothermal activity, can inhibit microbial growth and potentially toxify the material. This indicates that extraterrestrial meteoritic material and the environment on Early Earth could have shaped the nature of early microbial ecosystems by enhancing growth of microorganisms with metabolic capabilities favored in the presence of this material.

Nickel and the origin and early evolution of life.

Although nickel (Ni) is a minor element of the Earth's crust, it has played a major role in the evolution of life. This metal is a component of the active sites of several archaeal and bacterial anaerobic enzymes essential for bioenergy processes such as H2 and CO oxidation and CO2 fixation. Furthermore, Ni of meteoritic origin was probably involved in primordial organic phosphorylations. However, depending on its concentration, Ni can also be extremely toxic to most species. Through Earth's history, this paradoxical situation has provoked complex interactions between microorganisms, such as sulfate-reducing bacteria and the highly Ni-dependent methanogens. Ni-rich volcanic emissions have resulted in alterations of the biological carbon cycle caused by high archaeal production of greenhouse CH4 gas and the ensuing global temperature elevation. These emissions are also thought to have directly helped producing the most serious of the five major extinctions at the end of the Permian period.

Earth’s oldest tsunami deposit? Early Archaean high‐energy sediments in the ca 3.48 Ga Dresser Formation (Pilbara, Western Australia)

AbstractDynamic sedimentary processes are a key parameter for establishing the habitability of planetary surface environments on Earth and beyond and thus critical for reconstructing the early evolution of life on our planet. This paper presents a sedimentary section from the ca 3.48 Ga Dresser Formation (Pilbara Craton, Western Australia) that contains high‐energy reworked sediments, possibly representing the oldest reported tsunami deposit on Earth to date. Field and petrographic evidence (e.g. up to 20 cm large imbricated clasts, hummocky bedding, Bouma‐type graded sequences) indicate that the high‐energy deposit represents a bi‐directional succession of two debrite–turbidite couplets. This succession can best be explained by deposition related to passage and rebound of tsunami waves. Sedimentary processes were possibly influenced by highly dense silica‐rich seawater. The tsunami was probably triggered by local fault‐induced seismic activity since the Dresser Formation was deposited in a volcanic caldera basin that experienced syndepositional extensional growth faulting. However, alternative triggers (meteorite impact, volcanic eruption) or a combination thereof cannot be excluded. The results of this work indicate a subaquatic habitat that was subject to tsunami‐induced high‐energy disturbance. Potentially, this was a common situation on the early Archaean Earth, which experienced frequent impacts of extraterrestrial bodies. This study thus adds to the scarce record of early Archaean high‐energy deposits and stresses the relevance of high‐energy depositional events for the early evolution of life on Earth.

How low can they go? Aerobic respiration by microorganisms under apparent anoxia

Oxygen (O2) is the ultimate oxidant on Earth and its respiration confers such an energetic advantage that microorganisms have evolved the capacity to scavenge O2 down to nanomolar concentrations. The respiration of O2 at extremely low levels is proving to be common to diverse microbial taxa, including organisms formerly considered strict anaerobes. Motivated by recent advances in O2 sensing and DNA/RNA sequencing technologies, we performed a systematic review of environmental metatranscriptomes revealing that microbial respiration of O2 at nanomolar concentrations is ubiquitous and drives microbial activity in seemingly anoxic aquatic habitats. These habitats were key to the early evolution of life and are projected to become more prevalent in the near future due to anthropogenic-driven environmental change. Here, we summarize our current understanding of aerobic microbial respiration under apparent anoxia, including novel processes, their underlying biochemical pathways, the involved microorganisms, and their environmental importance and evolutionary origin.

Prebiotic triose glycolysis promoted by co-catalytic proline and phosphate in neutral water.

Proline and phosphate promote a near-quantitative aldol reaction between glycolaldehyde phosphate and formaldehyde at neutral pH in water. Our results demonstrate the important role of general acid-base catalysis in water and underscore the essential role that amino acid catalysis may have played in early evolution of life's core metabolic pathways.

Abiotic Formation of Calcium Oxalate under UV Irradiation and Implications for Biomarker Detection on Mars.

A major objective in the exploration of Mars is to test the hypothesis that the planet has ever hosted life. Biogenic compounds, especially biominerals, are believed to serve as biomarkers in Raman-assisted remote sensing missions. However, the prerequisite for the development of these minerals as biomarkers is the uniqueness of their biogenesis. Herein, tetragonal bipyramidal weddellite, a type of calcium oxalate, is successfully achieved by UV-photolyzing pyruvic acid (PA). The as-prepared products are identified and characterized by micro-Raman spectroscopy and field emission scanning electron microscopy. Persistent mineralization of weddellite is observed with altering key experimental parameters, including pH, Ca2+ and PA concentrations. In particular, the initial concentration of PA can significantly influence the morphology of weddellite crystal. Oxalate acid is commonly of biological origin; thus calcium oxalate is considered to be a biomarker. However, our results reveal that calcium oxalate can be harvested by a UV photolysis pathway. Moreover, prebiotic sources of organics (e.g., PA, glycine, alanine, and aspartic acid) have been proven to be available through abiotic pathways. Therefore, our results may provide a new abiotic pathway of calcium oxalate formation. Considering that calcium oxalate minerals have been taken as biosignatures for the origin and early evolution of life on Earth and astrobiological investigations, its formation and accumulation by the photolysis of abiological organic compounds should be taken into account.

Searching for Primary Evidence of Early Earth’s Atmospheric Evolution

What did Earth look like between one billion and two-and-a-half billion years ago? When did our atmosphere and oceans become oxygen-rich? Did oxygenation occur rapidly or during slow oscillations over hundreds of millions of years? These questions have been debated by scientists for decades because of their implications for the evolution of early life, and thus, our very understanding of life on Earth. Through their research, Dr Robert H. Rainbird and his team at the Geological Survey of Canada and Carleton University seek to answer these questions by investigating the ancient sedimentary rocks to the north of Lake Huron in Ontario.

Actinobacteria-mediated serpentine dissolution and implication for biosignatures on Mars

The search for traces of life is one of the principal objectives of Mars exploration. The global distribution of minerals associated with serpentinization in the Noachian terrains on Mars likely suggest that serpentinization commonly occurred early in the planets history. A consensus is that these reactions involved in the serpentinization may have provided the initial material and energy for the origin and early evolution of life on Earth. Comparably, the serpentine regions of Mars are potential target sites for the detection of the putative life on Mars. Herein, an actinobacterial species Streptomyces spp. FXJ8.102 is used as a model microbe to investigate the microbe-mediated dissolution of antigorite in liquid culture. The experimental results show that the strain can couple biomechanical and biochemical mechanisms in the serpentine dissolution, leading to the development of “cell-sized” and “cell-shaped” eroded pits/channels on the mineral surfaces, and the low Mg/Si ratios on the eroded sites. In addition, the cells can also induce the formation of secondary glushinskite during the dissolution process. By contrast, no distinguishable surface change on antigorite and secondary mineral formation can be observed in the control experiments without inoculation. Therefore, a collection of the features including the distinctive eroded texture and composition on serpentine surfaces, and the special mineral assemblage including the formation of secondary oxalate minerals may serve as a compelling biosignature for the search of life on Mars.

A halogen budget of the bulk silicate Earth points to a history of early halogen degassing followed by net regassing

Halogens are important tracers of various planetary formation and evolution processes, and an accurate understanding of their abundances in the Earth's silicate reservoirs can help us reconstruct the history of interactions among mantle, atmosphere, and oceans. The previous studies of halogen abundances in the bulk silicate Earth (BSE) are based on the assumption of constant ratios of element abundances, which is shown to result in a gross underestimation of the BSE halogen budget. Here we present a more robust approach using a log-log linear model. Using this method, we provide an internally consistent estimate of halogen abundances in the depleted mid-ocean ridge basalts (MORB)-source mantle, the enriched ocean island basalts (OIB)-source mantle, the depleted mantle, and BSE. Unlike previous studies, our results suggest that halogens in BSE are not more depleted compared to elements with similar volatility, thereby indicating sufficient halogen retention during planetary accretion. According to halogen abundances in the depleted mantle and BSE, we estimate that ∼87% of all stable halogens reside in the present-day mantle. Given our understanding of the history of mantle degassing and the evolution of crustal recycling, the revised halogen budget suggests that deep halogen cycle is characterized by efficient degassing in the early Earth and subsequent net regassing in the rest of Earth history. Such an evolution of deep halogen cycle presents a major step toward a more comprehensive understanding of ancient ocean alkalinity, which affects carbon partitioning within the hydrosphere, the stability of crustal and authigenic minerals, and the development of early life.

Chemical Nature of Hydrothermal Fluids Generated by Serpentinization and Carbonation of Komatiite: Implications for H2‐Rich Hydrothermal System and Ocean Chemistry in the Early Earth

AbstractH2‐rich ultramafic‐hosted hydrothermal systems are considered to be important places for the origin and early evolution of life. In this study, we conducted two hydrothermal serpentinization/carbonation experiments involving synthetic komatiite under CO2‐rich conditions to further understand the chemical nature of hydrothermal fluids in the komatiite‐hosted seafloor hydrothermal systems in the early Earth. The H2 concentration in fluid at 300°C is one order of magnitude lower than that under CO2‐free conditions, which revealed that the carbonation of komatiites suppressed H2 generation under CO2‐rich conditions. The steady‐state H2 concentrations in the fluid increased with increasing temperature, while the Fe content of carbonate minerals in the run products increased with decreasing temperature. This correlation suggested that Fe incorporation into the carbonate minerals would limit the H2 generation during the serpentinization of komatiites at each temperature. In addition, the pH of the fluid also depended on temperature. High‐temperature (>300°C) fluids became alkaline, whereas low‐temperature fluids became acidic. Thermodynamic calculations show that the acidic fluids were attributed to high water/rock ratio during the hydrothermal reactions. Consequently, H2‐poor and acidic fluids were likely generated at low temperatures. In contrast, the H2‐rich and alkaline hydrothermal fluids were generated at temperatures above 300°C, which suggests that high‐temperature seafloor hydrothermal systems may be more favorable than lower‐temperature systems for the emergence and early evolution of life in the Hadean ocean in terms of the formation of energy and electrochemical potentials between hydrothermal fluids and ambient seawater.

Authigenic uranium isotopes of late Proterozoic black shale

The evolution of early life is intimately related to environmental changes on Earth, and in particular, the accumulation of oxygen in the atmosphere and oceans. However, the record of environmental O2 abundance in the middle to late Proterozoic Eon, during which many new eukaryotic lineages emerged, is sparse and controversial. Here we present a uranium (U) isotope record from late Proterozoic shales from northwestern Canada, Arctic Canada (Baffin Island), Svalbard, and Greenland, coupled with a novel approach for inferring authigenic U isotope values (δ238Uauthigenic). A compilation comprising our new data and available literature data (854 δ238Uauthigenic values) through geologic time indicates a consistent rise in δ238Uauthigenic values following the Great Oxidation Event. This gradual increase in δ238U can be interpreted as an increase in the frequency of transient oxygenation events and also as a variation of U isotope fractionation factors between authigenic uptake and seawater (Δ238U) associated with different redox conditions occurring over the Earth's history. In conjunction with the U isotopic signature, we used previously published Fe speciation data from our samples to infer local controls on U incorporation and isotopic fractionation. The results suggest that late Proterozoic oceans were dominantly ferruginous, punctuated by periods of transient oxygenation. During these transient oxic conditions, high U isotope fractionation resulted in Δ238U values as high as ~1.2‰ relative to the δ238Ucrust. However, under ferruginous conditions, smaller isotopic fractionation led to Δ238U values <0.6‰. Integrating conclusions from our study with other geochemical studies suggests the occurrence of several spatially localized oxygenation events across the globe during the late Proterozoic. These conclusions help to better integrate geochemical and fossil records in the context of early evolution of complex life.

Magnesium isotope fractionation during alkaline brine evaporation and implications for Precambrian seawater chemistry

The chemical evolution of the ocean is one major component of the puzzle of how climate and life have co-evolved over the Earth's history. A “soda ocean” with high alkalinity, high pH, and low calcium concentration in Precambrian has been proposed to explain the emergence and evolution of early life. However, this hypothesis has not been widely accepted due to the lack of reliable tracers for the chemical composition of Precambrian seawater. Evaporite is formed during seawater/brine evaporation and thus has been widely used to reconstruct the ancient seawater/brine chemical composition. Here, evaporation experiments were conducted using Qinghai Lake (QHL) water, a modern soda lake, to provide an analogy of the Precambrian “soda ocean” evaporation and investigate the mineralogical and Mg isotopic signatures of alkaline brine-derived evaporites. Our results show that the evaporation path of QHL water overall covers the stages of hydrous Mg carbonates (hydromagnesite), halite, and bloedite [Na2Mg(SO4)2·4H2O] precipitation. The precipitation of hydrous Mg carbonates and bloedite is distinct from the modern seawater evaporation and is accompanied by the removal of up to 85% Mg from brine. The brine gradually becomes enriched in heavy Mg isotopes during evaporation due to the preferential incorporation of light Mg isotopes into precipitates. The fractionation of Mg isotopes is dominantly controlled by the bond structure during hydrous Mg carbonates and bloedite precipitation, and the latter is also slightly influenced by the kinetics in the highly concentrated brine. The Mg isotope fractionation during bloedite dissolution is limited due to the rapid congruent dissolution. The significant Mg isotopic fractionation observed within the hydrous Mg carbonates precipitation during the earliest QHL water evaporation indicates the potential Rayleigh distillation of Mg by alkalinity in the “soda ocean”, which is absent in the Phanerozoic oceans. Therefore, the large Mg isotope fractionation during alkaline brine evaporation can be applied to test the existence of Precambrian “soda oceans”.

Marine biomass changes during and after the Neoproterozoic Marinoan global glaciation

The late Neoproterozoic (645–535 Ma) represents a key geological period, when a climate shift and revolutionary biological innovations occurred during the Precambrian–Cambrian transition. The Marinoan glaciation impacted the climate and chemical composition of the oceans, restraining the evolution of early life. To elucidate evolutionary processes during the Marinoan–Ediacaran transition, this study presents biomarker evidence (molecular fossils) from the Nantuo Formation and the lower part of the Doushantuo Formation at the Jiulongwan section, China. Our results reveal possible photosynthetic activity (n-C17 + n-C19 [algae] and pristane + phytane [photosynthesis]) during the Marinoan glaciation, followed by low productivity during the early period of cap dolostone precipitation, and recovery of photosynthetic organisms (n-C17 + n-C19: from 0.00 to 0.96 μg/g TOC; pristane + phytane: from 0.00 to 3.6 μg/g TOC) or other bacteria (hopanes: from 0.00 to 0.07 ng/g TOC) during late cap carbonate deposition, with the expansion of eukaryotes (steranes/[hopanes + steranes]: from 0.0 to 0.6) after cap carbonate deposition in the early Ediacaran.

The evolution of evolutionary processes in organismal and cancer evolution

The evolution of early life and of contemporary viruses has been driven in significant part by random genetic mutations, while modern unicellular and organismal evolution primarily leverages evolved, efficient and active cell biology processes for adaptive changes prior to selection. Random mutations are often buffered by cell homeostasis, or they have a negative role, e.g., by causing death or monogenic diseases, or by triggering real-time cancer evolution. Accordingly, the Modern Synthesis theory no longer adequately describes the efficient, often punctuated and at times directionally adaptive natural genetic engineering (NGE) processes deduced from the DNA record of evolution.Similarly, the somatic mutation theory (SMT) of cancer describes driver mutations that can trigger oncogenesis, and passenger mutations characteristic of periods of genetic microevolution in cancer. At the precancerous stage, most somatic mutations are repaired or buffered in the cell, aberrant cells are removed, or organismal bioelectric tissue signals or other physiological functional networks maintain control of rogue, mutated cells. However, the SMT is not sufficient to describe the observed punctuated macroevolution of cancer-cell genes, chromosomes, karyotypes and epigenomes, nor of expressed cancer-cell transcriptomes, proteomes and epiproteomes, which include non-DNA-templated post-translational modifications, protein-protein interactions and metabolites. Moreover, punctuated cancer cell macroevolution often culminates in macro-effects, which include epithelial-mesenchymal transitions (EMT), cancer cell polyploidies and even giant multinucleated cancer cells that drive cancer progression, therapy resistance and metastasis. All of this cancer-cell evolution competes in a molecular and cellular arms race with host immune cells and antibodies, as well as with the host tumor microenvironment.Empirically observed punctuated, multilevel and multiclonal cancer macroevolution, and the concomitant, rapid co-development of the host immune system and tumor microenvironment, can occur with the efficiency, speed and lethality of cancer that is enabled by evolved, active natural genetic engineering (NGE) mechanisms. NGE affects both vertical cancer-cell genomic inheritance and evolution towards therapy resistance and metastasis, as well as viral or cancer-cell exosome vector-driven horizontal gene transfers that contributes to cancer cell cooperation, or to transforming previously non-cancerous somatic cells into destabilized cancer cells during metastasis.In addition, externally driven, irreversible and transferable (EDIT) adaptations are exemplified by mitotically heritable, non-templated cancer cell epigenetics, and by mitotically heritable cancer-cell surface protein and lipid glycosylation, as important examples of fast time-scale molecular evolution mechanisms in which genes are followers, similar to evo-devo processes in organismal evolution.

Structure-based insights into evolution of rhodopsins

Rhodopsins, most of which are proton pumps generating transmembrane electrochemical proton gradients, span all three domains of life, are abundant in the biosphere, and could play a crucial role in the early evolution of life on earth. Whereas archaeal and bacterial proton pumps are among the best structurally characterized proteins, rhodopsins from unicellular eukaryotes have not been well characterized. To fill this gap in the current understanding of the proton pumps and to gain insight into the evolution of rhodopsins using a structure-based approach, we performed a structural and functional analysis of the light-driven proton pump LR (Mac) from the pathogenic fungus Leptosphaeria maculans. The first high-resolution structure of fungi rhodopsin and its functional properties reveal the striking similarity of its membrane part to archaeal but not to bacterial rhodopsins. We show that an unusually long N-terminal region stabilizes the protein through direct interaction with its extracellular loop (ECL2). We compare to our knowledge all available structures and sequences of outward light-driven proton pumps and show that eukaryotic and archaeal proton pumps, most likely, share a common ancestor.

The potential versatility of RNA catalysis.

It is commonly thought that in the early development of life on this planet RNA would have acted both as a store of genetic information and as a catalyst. While a number of RNA enzymes are known in contemporary cells, they are largely confined to phosphoryl transfer reactions, whereas an RNA based metabolism would have required a much greater chemical diversity of catalysis. Here we discuss how RNA might catalyze a wider variety of chemistries, and particularly how information gleaned from riboswitches could suggest how ribozymes might recruit coenzymes to expand their chemical range. We ask how we might seek such activities in modern biology. This article is categorized under: RNA-Based Catalysis > Miscellaneous RNA-Catalyzed Reactions Regulatory RNAs/RNAi/Riboswitches > Riboswitches RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry.

Current Understanding of the Structure and Function of Pentapeptide Repeat Proteins.

The pentapeptide repeat protein (PRP) superfamily, identified in 1998, has grown to nearly 39,000 sequences from over 3300 species. PRPs, recognized as having at least eight contiguous pentapeptide repeats (PRs) of a consensus pentapeptide sequence, adopt a remarkable structure, namely, a right-handed quadrilateral β-helix with four consecutive PRs forming a single β-helix coil. Adjacent coils join together to form a β-helix “tower” stabilized by β-ladders on the tower faces and type I, type II, or type IV β-turns facilitating an approximately −90° redirection of the polypeptide chain joining one coil face to the next. PRPs have been found in all branches of life, but they are predominantly found in cyanobacteria. Cyanobacteria have existed on earth for more than two billion years and are thought to be responsible for oxygenation of the earth’s atmosphere. Filamentous cyanobacteria such as Nostoc sp. strain PCC 7120 may also represent the oldest and simplest multicellular organisms known to undergo cell differentiation on earth. Knowledge of the biochemical function of these PRPs is essential to understanding how ancient cyanobacteria achieved functions critical to early development of life on earth. PRPs are predicted to exist in all cyanobacteria compartments including thylakoid and cell-wall membranes, cytoplasm, and thylakoid periplasmic space. Despite their intriguing structure and importance to understanding ancient cyanobacteria, the biochemical functions of PRPs in cyanobacteria remain almost completely unknown. The precise biochemical function of only a handful of PRPs is currently known from any organisms, and three-dimensional structures of only sixteen PRPs or PRP-containing multidomain proteins from any organism have been reported. In this review, the current knowledge of the structures and functions of PRPs is presented and discussed.

Structural resolution of disaccharides through halogen anion complexation using negative trapped ion mobility spectrometry

Carbohydrates are an indispensable part of early life evolution. The determination of their structures is a key step to analyze their critical roles in biological systems. A variation of composition, glycosidic linkage, and (or) configuration between carbohydrate isomers induces structure diversity and brings challenges for their structural determination. Ion mobility spectrometry (IMS), an emerging gas-phase ion separation technology, has been considered as a promising tool for performing carbohydrate structure elucidation. In this work, eight disaccharides were analyzed by trapped ion mobility spectrometry-mass spectrometry (TIMS-MS) in the negative ion mode as the complexed form of [M + X]-, where M = disaccharide, and X = Cl, Br, and I. As compared to the positive ion analysis of the selected disaccharide in a sodiated form, a reversal charge state provided the ability to eliminate or even reverse the collision cross section (CCS) difference between disaccharide isomers. By the combination of TIMS analysis and the calculation of density functional theory, the only observed two conformers of ions [lactulose + I]- may result from different adduction sites for an iodide anion. Based on the comparison of different halogen adducts, the [M + I]- ion form exhibited more powerful ability for isomeric disaccharide differentiation with an average resolution (RP-P) of 1.17, which results in a 34.5% improvement as compared to the corresponding chloride adducts. This result indicates that the use of negative charge states, especially the complexation of an iodide anion, could be a supplemental strategy to commonly used positive ion analysis for carbohydrate separation.