Seminar - The Physiology and Habitat of LUCA
The concept of a last universal common ancestor of all cells (LUCA, or the progenote) is central to the study of early evolution and life's origin, yet information about how and where LUCA lived is lacking. Professor Martin (and team) has investigated all clusters and phylogenetic trees for 6.1 million protein coding genes from sequenced prokaryotic genomes in order to reconstruct the microbial ecology of LUCA. Among 286,514 protein clusters, 355 protein families (~0.1%) have been identified that trace to LUCA by phylogenetic criteria. Because these proteins are not universally distributed, they can shed light on LUCA's physiology. Their functions, properties, and prosthetic groups depict LUCA as anaerobic, CO2-fixing, H2-dependent with a Wood-Ljungdahl (WL) pathway, N2-fixing, and thermophilic. LUCA's biochemistry was replete with FeS clusters and radical reaction mechanisms. Its cofactors reveal dependence upon transition metals, flavins, S-adenosyl methionine (SAM), coenzyme A, ferredoxin, molybdopterin, corrins, and selenium. Its genetic code required nucleoside modifications and SAM-dependent methylations. The 355 phylogenies identify clostridia and methanogens, whose modern lifestyles resemble LUCA's, as basal among their respective domains. LUCA inhabited a geochemically active environment rich in H2, CO2, and iron. The data support the theory of an autotrophic origin of life involving the Wood–Ljungdahl pathway in a hydrothermal setting.
About Bill Martin
Professor Bill Martin is an evolutionary biologist with an active interest in biochemistry. He completed his undergraduate degree in Biology at the University of Hannover, and PhD in Genetics under the supervision of Heinz Saedler at the Max Plank Institute for Breeding Research in Cologne. After his PHD he joined the University of Braunschweig for 10 years. In 1999 he was appointed Professor at the Heinrich-Heine University Düsseldorf.
His research group at the Institute for Molecular Evolution pursues research on the biochemistry and evolution of chloroplasts, mitochondria (including their anaerobic forms, hydrogenosomes), and eukaryotes. We use laboratory experiments and bioinformatic techniques to pursue these questions and to probe even earlier phases of evolution, going back to life's origin, with the help of gene and genome comparisons.
Professor Martin has served as an Editor for many journals and is currently the Editor in Chief of Genome Biology and Evolution.
He has published 250 papers (see complete list).
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