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Prosdocimi F, de Farias ST. Major evolutionary transitions before cells: A journey from molecules to organisms. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2024; 191:11-24. [PMID: 38971326 DOI: 10.1016/j.pbiomolbio.2024.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 05/25/2024] [Accepted: 07/03/2024] [Indexed: 07/08/2024]
Abstract
Basing on logical assumptions and necessary steps of complexification along biological evolution, we propose here an evolutionary path from molecules to cells presenting four ages and three major transitions. At the first age, the basic biomolecules were formed and become abundant. The first transition happened with the event of a chemical symbiosis between nucleic acids and peptides worlds, which marked the emergence of both life and the process of organic encoding. FUCA, the first living process, was composed of self-replicating RNAs linked to amino acids and capable to catalyze their binding. The second transition, from the age of FUCA to the age of progenotes, involved the duplication and recombination of proto-genomes, leading to specialization in protein production and the exploration of protein to metabolite interactions in the prebiotic soup. Enzymes and metabolic pathways were incorporated into biology from protobiotic reactions that occurred without chemical catalysts, step by step. Then, the fourth age brought origin of organisms and lineages, occurring when specific proteins capable to stackle together facilitated the formation of peptidic capsids. LUCA was constituted as a progenote capable to operate the basic metabolic functions of a cell, but still unable to interact with lipid molecules. We present evidence that the evolution of lipid interaction pathways occurred at least twice, with the development of bacterial-like and archaeal-like membranes. Also, data in literature suggest at least two paths for the emergence of DNA biosynthesis, allowing the stabilization of early life strategies in viruses, archaeas and bacterias. Two billion years later, the eukaryotes arouse, and after 1,5 billion years of evolution, they finally learn how to evolve multicellularity via tissue specialization.
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Affiliation(s)
- Francisco Prosdocimi
- Laboratório de Biologia Teórica e de Sistemas, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Sávio Torres de Farias
- Laboratório de Genética Evolutiva Paulo Leminski, Centro de Ciências Exatas e da Natureza, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil; Network of Researchers on the Chemical Evolution of Life (NoRCEL), Leeds, LS7 3RB, UK
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Prosdocimi F, Cortines JR, José MV, Farias ST. Decoding viruses: An alternative perspective on their history, origins and role in nature. Biosystems 2023; 231:104960. [PMID: 37437771 DOI: 10.1016/j.biosystems.2023.104960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/16/2023] [Accepted: 06/17/2023] [Indexed: 07/14/2023]
Abstract
This article provides an alternative perspective on viruses, exploring their origins, ecology, and evolution. Viruses are recognized as the most prevalent biological entities on Earth, permeating nearly all environments and forming the virosphere-a significant biological layer. They play a crucial role in regulating bacterial populations within ecosystems and holobionts, influencing microbial communities and nutrient recycling. Viruses are also key drivers of molecular evolution, actively participating in the maintenance and regulation of ecosystems and cellular organisms. Many eukaryotic genomes contain genomic elements with viral origins, which contribute to organismal equilibrium and fitness. Viruses are involved in the generation of species-specific orphan genes, facilitating adaptation and the development of unique traits in biological lineages. They have been implicated in the formation of vital structures like the eukaryotic nucleus and the mammalian placenta. The presence of virus-specific genes absent in cellular organisms suggests that viruses may pre-date cellular life. Like progenotes, viruses are ribonucleoprotein entities with simpler capsid architectures compared to proteolipidic membranes. This article presents a comprehensive scenario describing major transitions in prebiotic evolution and proposes that viruses emerged prior to the Last Universal Common Ancestor (LUCA) during the progenote era. However, it is important to note that viruses do not form a monophyletic clade, and many viral taxonomic groups originated more recently as reductions of cellular structures. Thus, viral architecture should be seen as an ancient and evolutionarily stable strategy adopted by biological systems. The goal of this article is to reshape perceptions of viruses, highlighting their multifaceted significance in the complex tapestry of life and fostering a deeper understanding of their origins, ecological impact, and evolutionary dynamics.
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Affiliation(s)
- Francisco Prosdocimi
- Laboratório de Biologia Teórica e de Sistemas, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Juliana Reis Cortines
- Departamento de Virologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Brazil
| | - Marco V José
- Theoretical Biology Group, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, CDMX, Mexico
| | - Sávio Torres Farias
- Laboratório de Genética Evolutiva Paulo Leminsk, Departamento de Biologia Molecular, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil; Network of Researchers on the Chemical Evolution of Life (NoRCEL), Leeds, LS7 3RB, UK
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Prosdocimi F, de Farias ST. Origin of life: Drawing the big picture. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 180-181:28-36. [PMID: 37080436 DOI: 10.1016/j.pbiomolbio.2023.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/15/2023] [Accepted: 04/17/2023] [Indexed: 04/22/2023]
Abstract
Trying to provide a broad overview about the origin of life in Earth, the most significant transitions of life before cells are listed and discussed. The current approach emphasizes the symbiotic relationships that emerged with life. We propose a rational, stepwise scenario for the origin of life that starts with the origin of the first biomolecules and steps forward until the origins of the first cells. Along this path, we aim to provide a brief, though comprehensive theoretical model that will consider the following steps: (i) how nucleotides and other biomolecules could be made prebiotically in specific prebiotic refuges; (ii) how the first molecules of RNAs were formed; (iii) how the proto-peptidyl transferase center was built by the concatenation of proto-tRNAs; (iv) how the ribosome and the genetic code could be structured; (v) how progenotes could live and reproduce as "naked" ribonucleoprotein molecules; (vi) how peptides started to bind molecules in the prebiotic soup allowing biochemical pathways to evolve from those bindings; (vii) how genomes got bigger by the symbiotic relationship of progenotes and lateral transference of genetic material; (viii) how the progenote LUCA has been formed by assembling most biochemical routes; (ix) how the first virion capsids probably emerged and evolved; (x) how phospholipid membranes emerged probably twice by the evolution of lipid-binding proteins; (xi) how DNA synthesis have been formed in parallel in Bacteria and Archaea; and, finally, (xii) how DNA-based cells of Bacteria and Archaeabacteria have been constituted. The picture provided is conjectural and present epistemological gaps. Future research will help to advance into the elucidation of gaps and confirmation/refutation of current statements.
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Affiliation(s)
- Francisco Prosdocimi
- Laboratório de Biologia Teórica e de Sistemas, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Sávio Torres de Farias
- Laboratório de Genética Evolutiva Paulo Leminski, Centro de Ciências Exatas e da Natureza, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil; Network of Researchers on the Chemical Evolution of Life (NoRCEL), Leeds, LS7 3RB, UK
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de Farias ST, Furtado ANM, dos Santos Junior AP, José MV. Natural History of DNA-Dependent DNA Polymerases: Multiple Pathways to the Origins of DNA. Viruses 2023; 15:v15030749. [PMID: 36992459 PMCID: PMC10052633 DOI: 10.3390/v15030749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/09/2023] [Accepted: 03/12/2023] [Indexed: 03/17/2023] Open
Abstract
One of the major evolutionary transitions that led to DNA replacing RNA as the primary informational molecule in biological systems is still the subject of an intense debate in the scientific community. DNA polymerases are currently split into various families. Families A, B, and C are the most significant. In bacteria and some types of viruses, enzymes from families A and C predominate, whereas family B enzymes are more common in Archaea, Eukarya, and some types of viruses. A phylogenetic analysis of these three families of DNA polymerase was carried out. We assumed that reverse transcriptase was the ancestor of DNA polymerases. Our findings suggest that families A and C emerged and organized themselves when the earliest bacterial lineages had diverged, and that these earliest lineages had RNA genomes that were in transition—that is, the information was temporally stored in DNA molecules that were continuously being produced by reverse transcription. The origin of DNA and the apparatus for its replication in the mitochondrial ancestors may have occurred independently of DNA and the replication machinery of other bacterial lineages, according to these two alternate modes of genetic material replication. The family C enzymes emerged in a particular bacterial lineage before being passed to viral lineages, which must have functioned by disseminating this machinery to the other lineages of bacteria. Bacterial DNA viruses must have evolved at least twice independently, in addition to the requirement that DNA have arisen twice in bacterial lineages. We offer two possible scenarios based on what we know about bacterial DNA polymerases. One hypothesis contends that family A was initially produced and spread to the other lineages through viral lineages before being supplanted by the emergence of family C and acquisition at that position of the principal replicative polymerase. The evidence points to the independence of these events and suggests that the viral lineage’s acquisition of cellular replicative machinery was crucial for the establishment of a DNA genome in the other bacterial lineages, since these viral lineages may have served as a conduit for the machinery’s delivery to other bacterial lineages that diverged with the RNA genome. Our data suggest that family B initially established itself in viral lineages and was transferred to ancestral Archaea lineages before the group diversified; thus, the DNA genome must have emerged first in this cellular lineage. Our data point to multiple evolutionary steps in the origins of DNA polymerase, having started off at least twice in the bacterial lineage and once in the archaeal lineage. Given that viral lineages are implicated in a significant portion of the distribution of DNA replication equipment in both bacterial (families A and C) and Archaeal lineages (family A), our data point to a complex scenario.
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Affiliation(s)
- Sávio Torres de Farias
- Departamento de Biologia Molecular, Universidade Federal da Paraíba, João Pessoa 58051-900, Brazil
- Network of Researchers on the Chemical Evolution of Life (NoRCEL), Leeds LS7 3RB, UK
- Correspondence:
| | | | | | - Marco V. José
- Network of Researchers on the Chemical Evolution of Life (NoRCEL), Leeds LS7 3RB, UK
- Theoretical Biology Group, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México C.P. 04510, Mexico
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W B Jr M, A S R, P M, F B. Cellular and Natural Viral Engineering in Cognition-Based Evolution. Commun Integr Biol 2023; 16:2196145. [PMID: 37153718 PMCID: PMC10155641 DOI: 10.1080/19420889.2023.2196145] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
Neo-Darwinism conceptualizes evolution as the continuous succession of predominately random genetic variations disciplined by natural selection. In that frame, the primary interaction between cells and the virome is relegated to host-parasite dynamics governed by selective influences. Cognition-Based Evolution regards biological and evolutionary development as a reciprocating cognition-based informational interactome for the protection of self-referential cells. To sustain cellular homeorhesis, cognitive cells collaborate to assess the validity of ambiguous biological information. That collective interaction involves coordinate measurement, communication, and active deployment of resources as Natural Cellular Engineering. These coordinated activities drive multicellularity, biological development, and evolutionary change. The virome participates as the vital intercessory among the cellular domains to ensure their shared permanent perpetuation. The interactions between the virome and the cellular domains represent active virocellular cross-communications for the continual exchange of resources. Modular genetic transfers between viruses and cells carry bioactive potentials. Those exchanges are deployed as nonrandom flexible tools among the domains in their continuous confrontation with environmental stresses. This alternative framework fundamentally shifts our perspective on viral-cellular interactions, strengthening established principles of viral symbiogenesis. Pathogenesis can now be properly appraised as one expression of a range of outcomes between cells and viruses within a larger conceptual framework of Natural Viral Engineering as a co-engineering participant with cells. It is proposed that Natural Viral Engineering should be viewed as a co-existent facet of Natural Cellular Engineering within Cognition-Based Evolution.
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Affiliation(s)
- Miller W B Jr
- Banner Health Systems - Medicine, Paradise Valley, Arizona, AZ, USA
- CONTACT Miller W B Jr Paradise Valley, Arizona, AZ85253, USA
| | - Reber A S
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada
| | - Marshall P
- Department of Engineering, Evolution 2.0, Oak Park, IL, USA
| | - Baluška F
- Institute of Cellular and Molecular Botany, University of Bonn, Bonn, Germany
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Boratto PVM, Serafim MSM, Witt ASA, Crispim APC, de Azevedo BL, de Souza GAP, de Aquino ILM, Machado TB, Queiroz VF, Rodrigues RAL, Bergier I, Cortines JR, de Farias ST, dos Santos RN, Campos FS, Franco AC, Abrahão JS. A Brief History of Giant Viruses’ Studies in Brazilian Biomes. Viruses 2022; 14:v14020191. [PMID: 35215784 PMCID: PMC8875882 DOI: 10.3390/v14020191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/11/2022] [Accepted: 01/15/2022] [Indexed: 02/01/2023] Open
Abstract
Almost two decades after the isolation of the first amoebal giant viruses, indubitably the discovery of these entities has deeply affected the current scientific knowledge on the virosphere. Much has been uncovered since then: viruses can now acknowledge complex genomes and huge particle sizes, integrating remarkable evolutionary relationships that date as early as the emergence of life on the planet. This year, a decade has passed since the first studies on giant viruses in the Brazilian territory, and since then biomes of rare beauty and biodiversity (Amazon, Atlantic forest, Pantanal wetlands, Cerrado savannas) have been explored in the search for giant viruses. From those unique biomes, novel viral entities were found, revealing never before seen genomes and virion structures. To celebrate this, here we bring together the context, inspirations, and the major contributions of independent Brazilian research groups to summarize the accumulated knowledge about the diversity and the exceptionality of some of the giant viruses found in Brazil.
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Affiliation(s)
- Paulo Victor M. Boratto
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Mateus Sá M. Serafim
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Amanda Stéphanie A. Witt
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Ana Paula C. Crispim
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Bruna Luiza de Azevedo
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Gabriel Augusto P. de Souza
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Isabella Luiza M. de Aquino
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Talita B. Machado
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Victória F. Queiroz
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Rodrigo A. L. Rodrigues
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
| | - Ivan Bergier
- Embrapa Pantanal, Corumbá 79320-900, Mato Grosso do Sul, Brazil;
| | - Juliana Reis Cortines
- Departamento de Virologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-590, Rio de Janeiro, Brazil;
| | - Savio Torres de Farias
- Laboratório de Genética Evolutiva Paulo Leminsk, Departamento de Biologia Molecular, Universidade Federal da Paraíba, João Pessoa 58050-085, Paraíba, Brazil;
| | - Raíssa Nunes dos Santos
- Laboratório de Virologia, Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre 90.050-170, Rio Grande do Sul, Brazil; (R.N.d.S.); (F.S.C.); (A.C.F.)
| | - Fabrício Souza Campos
- Laboratório de Virologia, Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre 90.050-170, Rio Grande do Sul, Brazil; (R.N.d.S.); (F.S.C.); (A.C.F.)
| | - Ana Cláudia Franco
- Laboratório de Virologia, Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre 90.050-170, Rio Grande do Sul, Brazil; (R.N.d.S.); (F.S.C.); (A.C.F.)
| | - Jônatas S. Abrahão
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil; (P.V.M.B.); (M.S.M.S.); (A.S.A.W.); (A.P.C.C.); (B.L.d.A.); (G.A.P.d.S.); (I.L.M.d.A.); (T.B.M.); (V.F.Q.); (R.A.L.R.)
- Correspondence:
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Farias STD, Prosdocimi F. RNP-world: The ultimate essence of life is a ribonucleoprotein process. Genet Mol Biol 2022; 45:e20220127. [PMID: 36190700 PMCID: PMC9528728 DOI: 10.1590/1678-4685-gmb-2022-0127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/03/2022] [Indexed: 11/22/2022] Open
Abstract
The fundamental essence of life is based on process of interaction between nucleic acids and proteins. In a prebiotic world, amino acids, peptides, ions, and other metabolites acted in protobiotic routes at the same time on which RNAs performed catalysis and self-replication. Nevertheless, it was only when nucleic acids and peptides started to interact together in an organized process that life emerged. First, the ignition was sparked with the formation of a Peptidyl Transferase Center (PTC), possibly by concatenation of proto-tRNAs. This molecule that would become the catalytic site of ribosomes started a process of self-organization that gave origin to a protoorganism named FUCA, a ribonucleic ribosomal-like apparatus capable to polymerize amino acids. In that sense, we review hypotheses about the origin and early evolution of the genetic code. Next, populations of open biological systems named progenotes were capable of accumulating and exchanging genetic material, producing the first genomes. Progenotes then evolved in two paths: some presented their own ribosomes and others used available ribosomes in the medium to translate their encoded information. At some point, two different types of organisms emerged from populations of progenotes: the ribosome-encoding organisms (cells) and the capsid-encoding organisms (viruses).
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Affiliation(s)
- Sávio Torres de Farias
- Universidade Federal da Paraíba, Brazil; Network of Researchers on the Chemical Evolution of Life, UK
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Abstract
Although the knowledge about biological systems has advanced exponentially in recent decades, it is surprising to realize that the very definition of Life keeps presenting theoretical challenges. Even if several lines of reasoning seek to identify the essence of life phenomenon, most of these thoughts contain fundamental problem in their basic conceptual structure. Most concepts fail to identify either necessary or sufficient features to define life. Here, we analyzed the main conceptual frameworks regarding theoretical aspects that have been supporting the most accepted concepts of life, such as (i) the physical, (ii) the cellular and (iii) the molecular approaches. Based on an ontological analysis, we propose that Life should not be positioned under the ontological category of Matter. Yet, life should be better understood under the top-level ontology of "Process". Exercising an epistemological approach, we propose that the essential characteristic that pervades each and every living being is the presence of organic codes. Therefore, we explore theories in biosemiotics and code biology in order to propose a clear concept of life as a macrocode composed by multiple inter-related coding layers. This way, as life is a sort of metaphysical process of encoding, the living beings became the molecular materialization of that process. From the proposed concept, we show that the evolutionary process is a fundamental characteristic for life's maintenance but it is not necessary to define life, as many organisms are clearly alive but they do not participate in the evolutionary process (such as infertile hybrids). The current proposition opens a fertile field of debate in astrobiology, epistemology, biosemiotics, code biology and robotics.
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The Way forward for the Origin of Life: Prions and Prion-Like Molecules First Hypothesis. Life (Basel) 2021; 11:life11090872. [PMID: 34575021 PMCID: PMC8467930 DOI: 10.3390/life11090872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/11/2021] [Accepted: 08/22/2021] [Indexed: 11/18/2022] Open
Abstract
In this paper the hypothesis that prions and prion-like molecules could have initiated the chemical evolutionary process which led to the eventual emergence of life is reappraised. The prions first hypothesis is a specific application of the protein-first hypothesis which asserts that protein-based chemical evolution preceded the evolution of genetic encoding processes. This genetics-first hypothesis asserts that an “RNA-world era” came before protein-based chemical evolution and rests on a singular premise that molecules such as RNA, acetyl-CoA, and NAD are relics of a long line of chemical evolutionary processes preceding the Last Universal Common Ancestor (LUCA). Nevertheless, we assert that prions and prion-like molecules may also be relics of chemical evolutionary processes preceding LUCA. To support this assertion is the observation that prions and prion-like molecules are involved in a plethora of activities in contemporary biology in both complex (eukaryotes) and primitive life forms. Furthermore, a literature survey reveals that small RNA virus genomes harbor information about prions (and amyloids). If, as has been presumed by proponents of the genetics-first hypotheses, small viruses were present during an RNA world era and were involved in some of the earliest evolutionary processes, this places prions and prion-like molecules potentially at the heart of the chemical evolutionary process whose eventual outcome was life. We deliberate on the case for prions and prion-like molecules as the frontier molecules at the dawn of evolution of living systems.
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The Theory of Chemical Symbiosis: A Margulian View for the Emergence of Biological Systems (Origin of Life). Acta Biotheor 2021; 69:67-78. [PMID: 32783083 DOI: 10.1007/s10441-020-09388-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 08/04/2020] [Indexed: 10/23/2022]
Abstract
The theory of chemical symbiosis (TCS) suggests that biological systems started with the collaboration of two polymeric molecules existing in early Earth: nucleic acids and peptides. Chemical symbiosis emerged when RNA-like nucleic acid polymers happened to fold into 3D structures capable to bind amino acids together, forming a proto peptidyl-transferase center. This folding catalyzed the formation of quasi-random small peptides, some of them capable to bind this ribozyme structure back and starting to form an initial layer that would produce the larger subunit of the ribosome by accretion. TCS suggests that there is no chicken-and-egg problem into the emergence of biological systems as RNAs and peptides were of equal importance to the origin of life. Life has initially emerged when these two macromolecules started to interact in molecular symbiosis. Further, we suggest that life evolved into progenotes and cells due to the emergence of new layers of symbiosis. Mutualism is the strongest force in biology, capable to create novelties by emergent principles; on which the whole is bigger than the sum of the parts. TCS aims to apply the Margulian view of biology into the origins of life field.
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Is it possible that cells have had more than one origin? Biosystems 2021; 202:104371. [PMID: 33524470 DOI: 10.1016/j.biosystems.2021.104371] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/22/2021] [Accepted: 01/22/2021] [Indexed: 01/03/2023]
Abstract
Cells occupy a prominent place in the history of life in Earth. The central role of cellular organization can be understood by the fact that "cellular life" is often used as a synonym for life itself. Thus, most characteristics used to define cell overlap with those ones used to define life. However, innovative scenarios for the origin of life are bringing alternative views to describe how cells may have evolved from the open biological systems named progenotes. Here, using a logical and conceptual analysis, we re-evaluate the characteristics used to infer a single origin for cells. We argue that some evidences used to support cell monophyly, such as the presence of elements from the translation mechanism together with the universality of the genetic code, actually indicate a unique origin for all "biological systems", a term used to define not only cells, but also viruses and progenotes. Besides, we present evidence that at least two biochemical pathways as important as (i) DNA replication and (ii) lipid biosynthesis are not homologous between Bacteria and Archaea. The identities observed between the proteins involved in those pathways along representatives of these two ancestral domains of life are too low to indicate common genic ancestry. Altogether these facts can be seen as an indication that cellular organization has possibly evolved two or more times and that LUCA (the Last Universal Common Ancestor) may not have existed as a cellular entity. Thus, we aim to consider the possibility that different strategies acquired by biological systems to exist, such as viral, bacterial and archaeal were most likely originated independently from the evolution of different progenote populations.
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Harris HMB, Hill C. A Place for Viruses on the Tree of Life. Front Microbiol 2021; 11:604048. [PMID: 33519747 PMCID: PMC7840587 DOI: 10.3389/fmicb.2020.604048] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 12/14/2020] [Indexed: 12/15/2022] Open
Abstract
Viruses are ubiquitous. They infect almost every species and are probably the most abundant biological entities on the planet, yet they are excluded from the Tree of Life (ToL). However, there can be no doubt that viruses play a significant role in evolution, the force that facilitates all life on Earth. Conceptually, viruses are regarded by many as non-living entities that hijack living cells in order to propagate. A strict separation between living and non-living entities places viruses far from the ToL, but this may be theoretically unsound. Advances in sequencing technology and comparative genomics have expanded our understanding of the evolutionary relationships between viruses and cellular organisms. Genomic and metagenomic data have revealed that co-evolution between viral and cellular genomes involves frequent horizontal gene transfer and the occasional co-option of novel functions over evolutionary time. From the giant, ameba-infecting marine viruses to the tiny Porcine circovirus harboring only two genes, viruses and their cellular hosts are ecologically and evolutionarily intertwined. When deciding how, if, and where viruses should be placed on the ToL, we should remember that the Tree functions best as a model of biological evolution on Earth, and it is important that models themselves evolve with our increasing understanding of biological systems.
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Affiliation(s)
- Hugh M B Harris
- APC Microbiome Ireland, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Colin Hill
- APC Microbiome Ireland, College of Medicine and Health, University College Cork, Cork, Ireland.,School of Microbiology, University College Cork, Cork, Ireland
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