antonio lazcano | UNAM Universidad Nacional Autónoma de México (original) (raw)

Papers by antonio lazcano

When Adolph von Bäyer learned that Eduard Buchner had been awarded the 1907 Nobel Prize in Chemis... more When Adolph von Bäyer learned that Eduard Buchner had been awarded the 1907 Nobel Prize in Chemistry for his discovery of zym-ase, he remarked that “this will bring Buchner fame, even though he

We critically examine the proposal by Wächtershäuser (Prokaryotes 1:275–283,

Symposium - International Astronomical Union, 2004

Long before the idea of spontaneous generation was incorporated by JeanBaptiste de Lamarck into e... more Long before the idea of spontaneous generation was incorporated by JeanBaptiste de Lamarck into evolutionary biology to explain the first emergence of life, the possibility that other planets were inhabited had been discussed, sometimes in considerable detail, by scientists and philosophers alike (Lazcano 2001). More often than not, these were speculations that rested on the idea of a uniform universe but with little or no empirical basis. Today our approaches to the issue of life in the Universe have changed dramatically; neither the formation of planets nor the origin of life are seen as the result of inscrutable random events, but rather as natural outcomes of evolutionary events. The interconnection between these two processes is evident: understanding the formation of planets has major implications for our understanding of the early terrestrial environment, and therefore for the origin of living systems.

PLOS ONE, 2018

Background The imidazole group is an ubiquitous chemical motif present in several key types of bi... more Background The imidazole group is an ubiquitous chemical motif present in several key types of biomolecules. It is a structural moiety of purines, and plays a central role in biological catalysis as part of the side-chain of histidine, the amino acid most frequently found in the catalytic site of enzymes. Histidine biosynthesis starts with both ATP and the pentose phosphoribosyl pyrophosphate (PRPP), which is also the precursor for the de novo synthesis of purines. These two anabolic pathways are also connected by the imidazole intermediate 5-aminoimidazole-4-carboxamide ribotide (AICAR), which is synthesized in both routes but used only in purine biosynthesis. Rather surprisingly, the imidazole moieties of histidine and purines are synthesized by different, non-homologous enzymes. As discussed here, this phenomenon can be understood as a case of functional molecular convergence. Results In this work, we analyze these polyphyletic processes and argue that the independent origin of the corresponding enzymes is best explained by the differences in the function of each of the molecules to which the imidazole moiety is attached. Since the imidazole present in histidine is a catalytic moiety, its chemical arrangement allows it to act as an acid or a base. On the contrary, the de novo biosynthesis of purines starts with an activated ribose and all the successive intermediates are ribotides, with the key β-glycosidic bondage joining the ribose and the imidazole moiety. This prevents purine ribonucleotides to exhibit any imidazoledependent catalytic activity, and may have been the critical trait for the evolution of two separate imidazole-synthesizing-enzymes. We also suggest that, in evolutionary terms, the biosynthesis of purines predated that of histidine. Conclusions As reviewed here, other biosynthetic routes for imidazole molecules are also found in extant metabolism, including the autocatalytic cyclization that occurs during the formation of creatinine from creatine phosphate, as well as the internal cyclization of the Ala-Ser-Gly motif of

International Microbiology, Mar 17, 2010

Carbon dioxide fixation is a polyphyletic trait that has evolved in widely separated prokaryotic ... more Carbon dioxide fixation is a polyphyletic trait that has evolved in widely separated prokaryotic branches. The three principal CO 2-assimilation pathways are (i) the reductive pentose-phosphate cycle, i. e. the Calvin-Benson cycle; (ii) the reductive citric acid (or Arnon) cycle; and (iii) the net synthesis of acetyl-CoA from CO/CO 2 , or Wood pathway. Sequence analysis and the comparative biochemistry of these routes suggest that all of them were shaped to a considerable extent by the evolutionary recruitment of enzymes. Molecular phylogenetic trees show that the Calvin-Benson cycle was a relatively late development in the (eu)bacterial branch, suggesting that some form(s) of carbon assimilation may have been operative before chlorophyll-based photosynthesis. On the other hand, the ample phylogenetic distribution of both the Arnon and the Wood pathways does not allow us to infer which one of them is older. However, different lines of evidence, including experimental reports on the NiS/FeS-mediated CC bond formation from CO and CH 3 SH are used here to argue that the first CO 2-fixation route may have been a semienzymatic Wood-like pathway.

Mètode Revista de difusió de la investigació, 2015

The concept of an RNA world is a hypothesis firmly rooted in empirical data and is part of a long... more The concept of an RNA world is a hypothesis firmly rooted in empirical data and is part of a long and complex scientific perspective that goes back more than fifty years to the discovery of the central role RNA and ribonucleotides play in protein synthesis and biochemical reactions took place. As the understanding of RNA biology progressed, several independent proposals of protein-free primordial life forms were suggested. Although this possibility was strongly reinforced with the discovery of ribozymes, there are many definitions of the RNA world, including several contradictory ones. One could say that it was an early, perhaps primordial, stage during which RNA molecules played a much more conspicuous role in heredity and metabolism and, particularly, in the origin and early evolution of protein biosynthesis. The overwhelming evidence for the catalytic, regulatory, and structural properties of RNA molecules, combined with their ubiquity in cellular processes, can only be explained with the proposal that they played a key role in early evolution and perhaps in the origin of life itself.

International microbiology : the official journal of the Spanish Society for Microbiology, 2014

In recent decades, a number of hypotheses on the autotrophic origin of life have been presented. ... more In recent decades, a number of hypotheses on the autotrophic origin of life have been presented. These proposals invoke the emergence of reaction networks leading from CO or CO₂ to the organic molecules required for life. It has also been suggested that the last (universal) common ancestor (LCA or LUCA) of all extant cell lineages was a chemolitho-autotrophic thermophilic anaerobe. The antiquity of some carbon fixation pathways, the phylogenetic basal distribution of some autotrophic organisms, and the catalytic properties of iron-sulfur minerals have been advanced in support of these ideas. Here we critically examine the phylogenetic distribution and evolution of enzymes that are essential for two of the most ancient autotrophic means of metabolism: the reductive tricarboxylic acid (rTCA) cycle and the reductive acetyl-CoA pathway. Phylogenetic analysis of citryl-CoA synthetase and of citryl-CoA lyase, key enzymatic components of the rTCA cycle, and of CO dehydrogenase/acetyl-CoA s...

Origins and Evolution of Life

Origins of Life: Self-Organization and/or Biological Evolution?, 2009

The spontaneous assembly of amphiphiles into micelles and bilayer membranes, as well as the dynam... more The spontaneous assembly of amphiphiles into micelles and bilayer membranes, as well as the dynamical self-assembly properties of nucleic acids, suggest that selforganization phenomena played a role in the origin of life. However, current biology indicates that life could have not evolved in the absence of a genetic replicating mechanism insuring the stability and diversification of its basic components. This does not imply that explanations on the appearance of life should reduce themselves to the issue of the emergence of RNA or its predecessors.

Evolution: Education and Outreach, 2012

Astrobiology: Future Perspectives, 2005

Cold Spring Harbor Perspectives in Biology, 2010

Reports on Progress in Physics, 2002

This report has been reproduced directly from the best available copy.

Proceedings of the National Academy of Sciences, 2011

Archived samples from a previously unreported 1958 Stanley Miller electric discharge experiment c... more Archived samples from a previously unreported 1958 Stanley Miller electric discharge experiment containing hydrogen sulfide (H 2 S) were recently discovered and analyzed using high-performance liquid chromatography and time-of-flight mass spectrometry. We report here the detection and quantification of primary amine-containing compounds in the original sample residues, which were produced via spark discharge using a gaseous mixture of H 2 S, CH 4 , NH 3 , and CO 2 . A total of 23 amino acids and 4 amines, including 7 organosulfur compounds, were detected in these samples. The major amino acids with chiral centers are racemic within the accuracy of the measurements, indicating that they are not contaminants introduced during sample storage. This experiment marks the first synthesis of sulfur amino acids from spark discharge experiments designed to imitate primordial environments. The relative yield of some amino acids, in particular the isomers of aminobutyric acid, are the highest e...

Physics of Life Reviews, 2005

The basic tenet of the heterotrophic theory of the origin of life is that the maintenance and rep... more The basic tenet of the heterotrophic theory of the origin of life is that the maintenance and reproduction of the first living systems depended primarily on prebiotically synthesized organic molecules. It is unlikely that any single mechanism can account for the wide range of organic compounds that may have accumulated on the primitive Earth, suggesting that the prebiotic soup was formed by contributions from endogenous syntheses in reducing environments, metal sulphide-mediated synthesis in deep-sea vents, and exogenous sources such as comets, meteorites and interplanetary dust. The wide range of experimental conditions under which amino acids and nucleobases can be synthesized suggests that the abiotic syntheses of these monomers did not take place under a narrow range defined by highly selective reaction conditions, but rather under a wide variety of settings. The robustness of this type of chemistry is supported by the occurrence of most of these biochemical compounds in the Murchison meteorite. These results lend strong credence to the hypothesis that the emergence of life was the outcome of a long, but not necessarily slow, evolutionary processes. The origin of life may be best understood in terms of the dynamics and evolution of sets of chemical replicating entities. Whether such entities were enclosed within membranes is not yet clear, but given the prebiotic availability of amphiphilic compounds this may have well been the case. This scheme is not at odds with the theoretical models of self-organized emerging systems, but what is known of biology suggest that the essential traits of living systems could have not emerged in the absence of genetic material able to store, express and, upon replication, transmit to its progeny information capable of undergoing evolutionary change. How such genetic polymer first evolved is a central issue in origin-of-life studies.

Origins of Life and Evolution of Biospheres, 2013

The nature of the evolutionary process that led to the selection of the L αamino acids found in p... more The nature of the evolutionary process that led to the selection of the L αamino acids found in proteins is an unsolved issue in the study of the origin of life. Major prebiotic products are absent from the inventory of protein amino acids. We discuss the case of two hydrophobic amino acids: norvaline and norleucine.

Origins of Life and Evolution of Biospheres, 2011

Stanley Miller's 1958 H 2 S-containing experiment, which included a simulated prebiotic atmospher... more Stanley Miller's 1958 H 2 S-containing experiment, which included a simulated prebiotic atmosphere of methane (CH 4), ammonia (NH 3), carbon dioxide (CO 2), and hydrogen sulfide (H 2 S) produced several alkyl amino acids, including the α-, β-, and γisomers of aminobutyric acid (ABA) in greater relative yields than had previously been reported from his spark discharge experiments. In the presence of H 2 S, aspartic and glutamic acids could yield alkyl amino acids via the formation of thioimide intermediates. Radical chemistry initiated by passing H 2 S through a spark discharge could have also enhanced alkyl amino acid synthesis by generating alkyl radicals that can help form the aldehyde and ketone precursors to these amino acids. We propose mechanisms that may have influenced the synthesis of certain amino acids in localized environments rich in H 2 S and lightning discharges, similar to conditions near volcanic systems on the early Earth, thus contributing to the prebiotic chemical inventory of the primordial Earth.

Molecular Phylogenetics and Evolution, 2005

The last two decades have witnessed an unsurpassed effort aimed at reconstructing the history of ... more The last two decades have witnessed an unsurpassed effort aimed at reconstructing the history of life from the genetic information contained in extant organisms. The availability of many sequenced genomes has allowed the reconstruction of phylogenies from gene families and its comparison with traditional single-gene trees. However, the appearance of major discrepancies between both approaches questions whether horizontal gene transfer (HGT) has played a prominent role in shaping the topology of the Tree of Life. Recent attempts at solving this controversy and reaching a consensus tree combine molecular data with additional phylogenetic markers. Translation is a universal cellular function that involves a meaningful, highly conserved set of genes: both rRNA and r-protein operons have an undisputed phylogenetic value and rarely undergo HGT. Ribosomal function reflects the concerted expression of that genetic network and consequently yields information about the evolutionary paths followed by the organisms. Here we report on tree reconstruction using a measure of the performance of the ribosome: antibiotic sensitivity of protein synthesis. A large database has been used where 33 ribosomal systems belonging to the three major cellular lineages were probed against 38 protein synthesis inhibitors. Different definitions of distance between pairs of organisms have been explored, and the classical algorithm of bootstrap evaluation has been adapted to quantify the reliability of the reconstructions obtained. Our analysis returns a consistent phylogeny, where archaea are systematically affiliated to eukarya, in agreement with recent reconstructions which used information-processing systems. The integration of the information derived from relevant functional markers into current phylogenetic reconstructions might facilitate achieving a consensus Tree of Life.