Role of gene duplication in the evolution of complex physiological mechanisms : an assessment based on protein sequence data : (gene duplication, protein sequences, evolutionary trees, serine proteases, immunoglobulins, evolution of muscle types)

Genetic duplication has played a major role in the evolution of physiological complexity by creating originally redundant genes that evolved to produce related proteins in the organism. The related chains of certain polymeric molecules permit a range of similar activities while maintaining specificity. Related proteases form simple and complex cascade mechanisms that are poised for a controlled burst of activity, such as that seen in blood coagulation. Related genes arranged tandemly on the same chromosome may evolve to produce proteins that appear serially during development, as do the epsilon, gamma, and delta and beta chains of hemoglobin. Duplication can also produce an elongated gene that codes for a protein with multiple functional sites. Such proteins are important for the development of complex physiological functions such as muscle contraction. Polymeric structure, multiple genes, and internal duplication combine to give the immunoglobulins extraordinary functional diversity. Duplication of genetic material provides the raw material for the specialization of cell and tissue types.WINONA C. BARKER AND MARGARET O. DAYHOFF, National Biomedical Research Foundation, Georgetown University Medical Center, Washington, D.C

Evolution of major metabolic innovations in the Precambrian

A combination of the information on the metabolic capabilities of prokaryotes with a composite phylogenetic tree depicting an overview of prokaryote evolution based on the sequences of bacterial ferredoxin, 2Fe-2S ferredoxin, 5S ribosomal RNA, and c-type cytochromes shows three zones of major metabolic innovation in the Precambrian. The middle of these, which reflects the genesis of oxygen releasing photosynthesis and aerobic respiration, links metabolic innovations of the anaerobic stem on the one hand and, on the other, proliferation of aerobic bacteria and the symbiotic associations leading to the eukaryotes. We consider especially those pathways where information on the structure of the enzymes is known. Halobacterium and Thermoplasma (archaebacteria) do not belong to a totally independent line on the basis of the composite tree but branch from the eukaryote cytoplasmic line

Atlas of protein sequence and structure.

Editors: 1965- M. O. Dayhoff and R. V. Eck.Mode of access: Internet

Collecting, Comparing, and Computing Sequences: The Making of Margaret O. Dayhoff’s Atlas of Protein Sequence and Structure, 1954–1965

Collecting, comparing, and computing molecular sequences are among the most prevalent practices in contemporary biological research. They represent a specific way of producing knowledge. This paper explores the historical development of these practices, focusing on the work of Margaret O. Dayhoff, Richard V. Eck, and Robert S. Ledley, who produced the first computer-based collection of protein sequences, published in book format in 1965 as the Atlas of Protein Sequence and Structure. While these practices are generally associated with the rise of molecular evolution in the 1960s, this paper shows that they grew out of research agendas from the previous decade, including the biochemical investigation of the relations between the structures and function of proteins and the theoretical attempt to decipher the genetic code. It also shows how computers became essential for the handling and analysis of sequence data. Finally, this paper reflects on the relationships between experimenting and collecting as two distinct ‘‘ways of knowing’’ that were essential for the transformation of the life sciences in the twentieth century