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The 160-Kilobase Genome of the Bacterial Endosymbiont Carsonella
Atsushi Nakabachi,1,2*Atsushi Yamashita,3Hidehiro Toh,3,4Hajime Ishikawa,5Helen E. Dunbar,2Nancy A. Moran,2Masahira Hattori6,7*
Previous studies have suggested that the minimal cellular genomecould be as small as 400 kilobases. Here, we report the completegenome sequence of the psyllid symbiont Carsonella ruddii, whichconsists of a circular chromosome of 159,662 base pairs, averaging16.5% GC content. It is by far the smallest and most AT-richbacterial genome yet characterized. The genome has a high codingdensity (97%) with many overlapping genes and reduced gene length.Genes for translation and amino acid biosynthesis are relativelywell represented, but numerous genes considered essential forlife are missing, suggesting that Carsonella may have achievedorganelle-like status.
1 Environmental Molecular Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan. 2 Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA. 3 Kitasato Institute for Life Sciences, Kitasato University, Sagamihara, Kanagawa 228-8555, Japan. 4 Center for Basic Research, Kitasato Institute, Minato-ku, Tokyo 108-8641, Japan. 5 School of General Education, University of the Air, Mihama, Chiba 261-8586, Japan. 6 Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8561, Japan. 7 Genome Core Technology Facility, RIKEN Genomic Sciences Center, Yokohama, Kanagawa 230-0045, Japan.
These authors contributed equally to this work.
* To whom correspondence should be addressed. E-mail: bachi{at}email.arizona.edu (A.N.); hattori{at}k.u-tokyo.ac.jp (M.H.)
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