1. Institut für Pharmazeutische Biologie, Universität Frankfurt (Biozentrum), Frankfurt am Main, 60439, Germany
2. Max-Planck-Institut für Biochemie, 82152 Martinsried, Germany
3. Molecular Microbiology, Biozentrum der Universität, 4056 Basel, Switzerland
4. A.-Butenandt-Institut/Zellbiologie, Ludwig-Maximilians-Universität, 80336 München, Germany
5. Max-Planck-Institut für Entwicklungsbiologie, 72076 Tübingen, Germany
6. Children's Hospital Oakland – BACPAC Resources, Oakland, California 94609, USA
7. Baylor College of Medicine, Houston, Texas 77030, USA
8. The Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
9. University of Dundee, MSI/WTB Complex, Dundee, UK
10. MRC Laboratory, of Molecular Biology, Cambridge CB2 2QH, UK
11. IMB Jena, Department of Genome Analysis, Beutenbergstr. 11, 07745 Jena, Germany
12. Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Köln, Germany
13. Medical Research Council Laboratory of Molecular Biology, MRC Centre, Hills Road, Cambridge CB2 2QH, UK
14. Grup de Recerca en Informatica Biomedica, Institut Municipal d'Inveastigació Mèdica, Universitat Pompeu Fabra, Centre de Regulació Genòmica, 08003 Barcelona, Spain
15. Princeton University, Princeton, New Jersey 08544, USA
16. The Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
17. Friedrich Schiller Universität, 07743 Jena, Germany

Correspondence to: Gernot Glöckner¹Ludwig Eichinger²Angelika A. Noegel² Correspondence and requests for materials should be addressed to A.A.N. (e-mail: Email: noegel@uni-koeln.de) or G.G. (e-mail: Email: gernot@imb-jena.de).

Abstract

The genome of the lower eukaryote Dictyostelium discoideum comprises six chromosomes. Here we report the sequence of the largest, chromosome 2, which at 8 megabases (Mb) represents about 25% of the genome. Despite an A + T content of nearly 80%, the chromosome codes for 2,799 predicted protein coding genes and 73 transfer RNA genes. This gene density, about 1 gene per 2.6 kilobases (kb), is surpassed only by Saccharomyces cerevisiae (one per 2 kb) and is similar to that of Schizosaccharomyces pombe (one per 2.5 kb)^{1, 2}. If we assume that the other chromosomes have a similar gene density, we can expect around 11,000 genes in the D. discoideum genome. A significant number of the genes show higher similarities to genes of vertebrates than to those of other fully sequenced eukaryotes^{1, 2, 3, 4, 5, 6}. This analysis strengthens the view that the evolutionary position of D. discoideum is located before the branching of metazoa and fungi but after the divergence of the plant kingdom⁷, placing it close to the base of metazoan evolution.