Origin and evolution of photosynthesis: clues from genome comparison Armen Y. Mulkidjanian 1,2 , Eugene V. Koonin 3 , Kira S. Makarova 3 , Robert Haselkorn 4 and Michael Y. Galperin 3 1 School of Physics, University of Osnabrück, D-49069 Osnabrück, Germany, and 2 A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119899, Russia; 3 National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA; 4 Department of Molecular Genetics and Cell Biology, University of Chicago, 920 East 58th St., Chicago, IL 60637, USA Keywords: origin of photosynthesis, comparative genomics, evolution, cyanobacteria, phototrophic organisms.