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https://www.readbyqxmd.com/read/28333103/the-genetic-code-and-rna-amino-acid-affinities
#1
REVIEW
Michael Yarus
A significant part of the genetic code likely originated via a chemical interaction, which should be experimentally verifiable. One possible verification relates bound amino acids (or perhaps their activated congeners) and ribonucleotide sequences within cognate RNA binding sites. To introduce this interaction, I first summarize how amino acids function as targets for RNA binding. Then the experimental method for selecting relevant RNA binding sites is characterized. The selection method's characteristics are related to the investigation of the RNA binding site model treated at the outset...
March 23, 2017: Life
https://www.readbyqxmd.com/read/28335420/efforts-and-challenges-in-engineering-the-genetic-code
#2
REVIEW
Xiao Lin, Allen Chi Shing Yu, Ting Fung Chan
This year marks the 48th anniversary of Francis Crick's seminal work on the origin of the genetic code, in which he first proposed the "frozen accident" hypothesis to describe evolutionary selection against changes to the genetic code that cause devastating global proteome modification. However, numerous efforts have demonstrated the viability of both natural and artificial genetic code variations. Recent advances in genetic engineering allow the creation of synthetic organisms that incorporate noncanonical, or even unnatural, amino acids into the proteome...
March 14, 2017: Life
https://www.readbyqxmd.com/read/28272354/micrometer-scale-membrane-transition-of-supported-lipid-bilayer-membrane-reconstituted-with-cytosol-of-dictyostelium-discoideum
#3
Kei Takahashi, Taro Toyota
The transformation of the supported lipid bilayer (SLB) membrane by extracted cytosol from living resources, has recently drawn much attention. It enables us to address the question of whether the purified phospholipid SLB membrane, including lipids related to amoeba locomotion, which was discussed in many previous studies, exhibits membrane deformation in the presence of cytosol extracted from amoeba; Methods: In this report, a method for reconstituting a supported lipid bilayer (SLB) membrane, composed of purified phospholipids and cytosol extracted from Dictyostelium discoideum, is described...
March 7, 2017: Life
https://www.readbyqxmd.com/read/28264473/future-of-the-genetic-code
#4
REVIEW
Hong Xue, J Tze-Fei Wong
The methods for establishing synthetic lifeforms with rewritten genetic codes comprising non-canonical amino acids (NCAA) in addition to canonical amino acids (CAA) include proteome-wide replacement of CAA, insertion through suppression of nonsense codon, and insertion via the pyrrolysine and selenocysteine pathways. Proteome-wide reassignments of nonsense codons and sense codons are also under development. These methods enable the application of NCAAs to enrich both fundamental and applied aspects of protein chemistry and biology...
February 28, 2017: Life
https://www.readbyqxmd.com/read/28264444/highly-conserved-elements-and-chromosome-structure-evolution-in-mitochondrial-genomes-in-ciliates
#5
Roman A Gershgorin, Konstantin Yu Gorbunov, Oleg A Zverkov, Lev I Rubanov, Alexandr V Seliverstov, Vassily A Lyubetsky
Recent phylogenetic analyses are incorporating ultraconserved elements (UCEs) and highly conserved elements (HCEs). Models of evolution of the genome structure and HCEs initially faced considerable algorithmic challenges, which gave rise to (often unnatural) constraints on these models, even for conceptually simple tasks such as the calculation of distance between two structures or the identification of UCEs. In our recent works, these constraints have been addressed with fast and efficient solutions with no constraints on the underlying models...
February 27, 2017: Life
https://www.readbyqxmd.com/read/28230768/bioinformatic-analysis-reveals-archaeal-trna-tyr-and-trna-trp-identities-in-bacteria
#6
Takahito Mukai, Noah M Reynolds, Ana Crnković, Dieter Söll
The tRNA identity elements for some amino acids are distinct between the bacterial and archaeal domains. Searching in recent genomic and metagenomic sequence data, we found some candidate phyla radiation (CPR) bacteria with archaeal tRNA identity for Tyr-tRNA and Trp-tRNA synthesis. These bacteria possess genes for tyrosyl-tRNA synthetase (TyrRS) and tryptophanyl-tRNA synthetase (TrpRS) predicted to be derived from DPANN superphylum archaea, while the cognate tRNA(Tyr) and tRNA(Trp) genes reveal bacterial or archaeal origins...
February 21, 2017: Life
https://www.readbyqxmd.com/read/28208827/on-the-uniqueness-of-the-standard-genetic-code
#7
Gabriel S Zamudio, Marco V José
In this work, we determine the biological and mathematical properties that are sufficient and necessary to uniquely determine both the primeval RNY (purine-any base-pyrimidine) code and the standard genetic code (SGC). These properties are: the evolution of the SGC from the RNY code; the degeneracy of both codes, and the non-degeneracy of the assignments of aminoacyl-tRNA synthetases (aaRSs) to amino acids; the wobbling property; the consideration that glycine was the first amino acid; the topological and symmetrical properties of both codes...
February 13, 2017: Life
https://www.readbyqxmd.com/read/28208756/homocysteine-editing-thioester-chemistry-coenzyme-a-and-the-origin-of-coded-peptide-synthesis-%C3%A2
#8
REVIEW
Hieronim Jakubowski
Aminoacyl-tRNA synthetases (AARSs) have evolved "quality control" mechanisms which prevent tRNA aminoacylation with non-protein amino acids, such as homocysteine, homoserine, and ornithine, and thus their access to the Genetic Code. Of the ten AARSs that possess editing function, five edit homocysteine: Class I MetRS, ValRS, IleRS, LeuRS, and Class II LysRS. Studies of their editing function reveal that catalytic modules of these AARSs have a thiol-binding site that confers the ability to catalyze the aminoacylation of coenzyme A, pantetheine, and other thiols...
February 9, 2017: Life
https://www.readbyqxmd.com/read/28106741/the-role-of-lipid-membranes-in-life-s-origin
#9
REVIEW
David Deamer
At some point in early evolution, life became cellular. Assuming that this step was required for the origin of life, there would necessarily be a pre-existing source of amphihilic compounds capable of assembling into membranous compartments. It is possible to make informed guesses about the properties of such compounds and the conditions most conducive to their self-assembly into boundary structures. The membranes were likely to incorporate mixtures of hydrocarbon derivatives between 10 and 20 carbons in length with carboxylate or hydroxyl head groups...
January 17, 2017: Life
https://www.readbyqxmd.com/read/28067845/selection-of-prebiotic-molecules-in-amphiphilic-environments
#10
Christian Mayer, Ulrich Schreiber, María J Dávila
A basic problem in all postulated pathways of prebiotic chemistry is the low concentration which generally is expected for interesting reactants in fluid environments. Even though compounds, like nucleobases, sugars or peptides, principally may form spontaneously under environmental conditions, they will always be rapidly diluted in an aqueous environment. In addition, any such reaction leads to side products which often exceed the desired compound and generally hamper the first steps of a subsequent molecular evolution...
January 7, 2017: Life
https://www.readbyqxmd.com/read/28054992/mobility-of-a-mononucleotide-within-a-lipid-matrix-a-neutron-scattering-study
#11
Loreto Misuraca, Francesca Natali, Laura da Silva, Judith Peters, Bruno Demé, Jacques Ollivier, Tilo Seydel, Valerie Laux-Lesourd, Michael Haertlein, Giuseppe Zaccai, David Deamer, Marie Christine Maurel
An essential question in studies on the origins of life is how nucleic acids were first synthesized and then incorporated into compartments about 4 billion years ago. A recent discovery is that guided polymerization within organizing matrices could promote a non-enzymatic condensation reaction allowing the formation of RNA-like polymers, followed by encapsulation in lipid membranes. Here, we used neutron scattering and deuterium labelling to investigate 5'-adenosine monophosphate (AMP) molecules captured in a multilamellar phospholipid matrix...
January 4, 2017: Life
https://www.readbyqxmd.com/read/28035953/arsenite-as-an-electron-donor-for-anoxygenic-photosynthesis-description-of-three-strains-of-ectothiorhodospira-from-mono-lake-california-and-big-soda-lake-nevada
#12
Shelley Hoeft McCann, Alison Boren, Jaime Hernandez-Maldonado, Brendon Stoneburner, Chad W Saltikov, John F Stolz, Ronald S Oremland
Three novel strains of photosynthetic bacteria from the family Ectothiorhodospiraceae were isolated from soda lakes of the Great Basin Desert, USA by employing arsenite (As(III)) as the sole electron donor in the enrichment/isolation process. Strain PHS-1 was previously isolated from a hot spring in Mono Lake, while strain MLW-1 was obtained from Mono Lake sediment, and strain BSL-9 was isolated from Big Soda Lake. Strains PHS-1, MLW-1, and BSL-9 were all capable of As(III)-dependent growth via anoxygenic photosynthesis and contained homologs of arxA, but displayed different phenotypes...
December 26, 2016: Life
https://www.readbyqxmd.com/read/27918435/piecemeal-buildup-of-the-genetic-code-ribosomes-and-genomes-from-primordial-trna-building-blocks
#13
Derek Caetano-Anollés, Gustavo Caetano-Anollés
The origin of biomolecular machinery likely centered around an ancient and central molecule capable of interacting with emergent macromolecular complexity. tRNA is the oldest and most central nucleic acid molecule of the cell. Its co-evolutionary interactions with aminoacyl-tRNA synthetase protein enzymes define the specificities of the genetic code and those with the ribosome their accurate biosynthetic interpretation. Phylogenetic approaches that focus on molecular structure allow reconstruction of evolutionary timelines that describe the history of RNA and protein structural domains...
December 2, 2016: Life
https://www.readbyqxmd.com/read/27916886/cyanobacteria-as-chassis-for-industrial-biotechnology-progress-and-prospects
#14
REVIEW
Lamya Al-Haj, Yuen Tin Lui, Raeid M M Abed, Mohamed A Gomaa, Saul Purton
Cyanobacteria hold significant potential as industrial biotechnology (IB) platforms for the production of a wide variety of bio-products ranging from biofuels such as hydrogen, alcohols and isoprenoids, to high-value bioactive and recombinant proteins. Underpinning this technology, are the recent advances in cyanobacterial "omics" research, the development of improved genetic engineering tools for key species, and the emerging field of cyanobacterial synthetic biology. These approaches enabled the development of elaborate metabolic engineering programs aimed at creating designer strains tailored for different IB applications...
November 30, 2016: Life
https://www.readbyqxmd.com/read/27898036/screening-of-a-haloferax-volcanii-transposon-library-reveals-novel-motility-and-adhesion-mutants
#15
Georgio Legerme, Evan Yang, Rianne N Esquivel, Saija Kiljunen, Harri Savilahti, Mechthild Pohlschroder
Archaea, like bacteria, use type IV pili to facilitate surface adhesion. Moreover, archaeal flagella-structures required for motility-share a common ancestry with type IV pili. While the characterization of archaeal homologs of bacterial type IV pilus biosynthesis components has revealed important aspects of flagellum and pilus biosynthesis and the mechanisms regulating motility and adhesion in archaea, many questions remain. Therefore, we screened a Haloferax volcanii transposon insertion library for motility mutants using motility plates and adhesion mutants, using an adapted air-liquid interface assay...
November 26, 2016: Life
https://www.readbyqxmd.com/read/27827919/taming-prebiotic-chemistry-the-role-of-heterogeneous-and-interfacial-catalysis-in-the-emergence-of-a-prebiotic-catalytic-information-polymer-system
#16
REVIEW
Pierre-Alain Monnard
Cellular life is based on interacting polymer networks that serve as catalysts, genetic information and structural molecules. The complexity of the DNA, RNA and protein biochemistry suggests that it must have been preceded by simpler systems. The RNA world hypothesis proposes RNA as the prime candidate for such a primal system. Even though this proposition has gained currency, its investigations have highlighted several challenges with respect to bulk aqueous media: (1) the synthesis of RNA monomers is difficult; (2) efficient pathways for monomer polymerization into functional RNAs and their subsequent, sequence-specific replication remain elusive; and (3) the evolution of the RNA function towards cellular metabolism in isolation is questionable in view of the chemical mixtures expected on the early Earth...
November 4, 2016: Life
https://www.readbyqxmd.com/read/27618105/functional-annotations-of-paralogs-a-blessing-and-a-curse
#17
Rémi Zallot, Katherine J Harrison, Bryan Kolaczkowski, Valérie de Crécy-Lagard
Gene duplication followed by mutation is a classic mechanism of neofunctionalization, producing gene families with functional diversity. In some cases, a single point mutation is sufficient to change the substrate specificity and/or the chemistry performed by an enzyme, making it difficult to accurately separate enzymes with identical functions from homologs with different functions. Because sequence similarity is often used as a basis for assigning functional annotations to genes, non-isofunctional gene families pose a great challenge for genome annotation pipelines...
September 8, 2016: Life
https://www.readbyqxmd.com/read/27608044/evidence-supporting-the-uptake-and-genomic-incorporation-of-environmental-dna-in-the-ancient-asexual-bdelloid-rotifer-philodina-roseola
#18
Olaf R P Bininda-Emonds, Claus Hinz, Wilko H Ahlrichs
Increasing evidence suggests that bdelloid rotifers regularly undergo horizontal gene transfer, apparently as a surrogate mechanism of genetic exchange in the absence of true sexual reproduction, in part because of their ability to withstand desiccation. We provide empirical support for this latter hypothesis using the bdelloid Philodina roseola, which we demonstrate to readily internalize environmental DNA in contrast to a representative monogonont rotifer (Brachionus rubens), which, like other monogononts, is facultative sexual and cannot withstand desiccation...
September 6, 2016: Life
https://www.readbyqxmd.com/read/27598206/bipyrimidine-signatures-as-a-photoprotective-genome-strategy-in-g-c-rich-halophilic-archaea
#19
Daniel L Jones, Bonnie K Baxter
Halophilic archaea experience high levels of ultraviolet (UV) light in their environments and demonstrate resistance to UV irradiation. DNA repair systems and carotenoids provide UV protection but do not account for the high resistance observed. Herein, we consider genomic signatures as an additional photoprotective strategy. The predominant forms of UV-induced DNA damage are cyclobutane pyrimidine dimers, most notoriously thymine dimers (T^Ts), which form at adjacent Ts. We tested whether the high G + C content seen in halophilic archaea serves a photoprotective function through limiting T nucleotides, and thus T^T lesions...
September 2, 2016: Life
https://www.readbyqxmd.com/read/27571106/the-genetic-code-francis-crick-s-legacy-and-beyond
#20
EDITORIAL
Koji Tamura
Francis Crick (Figure 1) was born on 8 June 1916, in Northampton, England, and passed away on 28 July 2004, in La Jolla, California, USA.[...].
August 25, 2016: Life
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