Research Group Biochemical Ecology and Molecular Evolution

Scientific background

Gene duplication

Gene duplication is a very central mechanism of evolution. Among “de novo” gene birth, gene duplication provides the genetic raw material for the evolutionary playground. Duplication can affect single genes (small scale duplications) or large fragments up to whole genomes. Generalized, a duplicated gene can experience three different fates: a) it accumulates deleterious mutations, becomes a pseudogene and finally gets purged from the genome (nonfunctionalization), b) the functions of the ancestor are divided so that both copies remain functional, but both copies together are necessary to maintain the ancestral function (subfunctionalization), and c) it can gain a new function (neofunctionalization) via beneficial mutations.

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Which of these three different outcomes eventually awaits a duplicated gene is studied in detail to finally understand which molecular factors shape the fate of a duplicated gene. Such factors can be: expression level or the number of interaction partners of the gene product. For example, one hypothesis is, that genes encoding proteins that interact tightly with many other proteins (e.g. proteins that form a complex) are less often duplicated. Furthermore, the quaternary protein structure may also affect to the duplicability of a gene. But apart from the general duplicability of a gene, the evolutionary trajectory of a how a gene adopted a new function and which mutational steps were involved are most interesting.

Up to date we could show that within the Morning Glories a single gene duplication in the early evolution of this plant family provided the gene material for HSS evolution. Its new function in PA biosynthesis, which involves basically a change in substrate specificity, however evolved possibly in parallel in the two PA-producing genera of this family, namely Merremia und Ipomoea. We will combine bioinformatic tools and biochemical characterization of promising candidate proteins to test this scenario.