title: Divergent evolution of (betaalpha)8-barrel enzymes.
abstract: The (betaalpha)8-barrel is the most versatile and most frequently encountered fold among enzymes. It is an interesting question how the contemporary (betaalpha)8-barrels are evolutionarily related and by which mechanisms they evolved from more simple precursors. Comprehensive comparisons of amino acid sequences and three-dimensional structures suggest that a large fraction of the known (betaalpha)8-barrels have divergently evolved from a common ancestor. The mutational interconversion of enzymatic activities of several (betaalpha)8-barrels further supports their common evolutionary origin. Moreover, the high structural similarity between the N- and C-terminal (betaalpha)4 units of two (betaalpha)8-barrel enzymes from histidine biosynthesis indicates that the contemporary proteins evolved by tandem duplication and fusion of the gene of an ancestral 'half-barrel' precursor. In support of this hypothesis, recombinantly produced 'half-barrels' were shown to be folded, dimeric proteins.
authors.affiliation: Institut für Biochemie, Universität zu Köln, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Henn-Sax
authors.forename: B
authors.initials: B
authors.lastname: Höcker
authors.forename: M
authors.initials: M
authors.lastname: Wilmanns
authors.forename: R
authors.initials: R
authors.lastname: Sterner
mesh_terms: D005075:Biological Evolution; D004798:Enzymes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011487:Protein Conformation
chemical_list: D004798:Enzymes; D010710:Phosphates