The Genome of Archaeoglobus fulgidus
Hans-Peter KLENK*a, Owen WHITEa, Jean-Francois TOMBa, Karen E. NELSONa, Rebecca A. CLAYTONa, Karen A. KETCHUMa, Nikos C. KYRPIDESb, David GRAHAMb, Gary J. OLSENb, Claire M. FRASERa, Carl R. WOESEb, and J. Craig VENTERa
a The Institute for Genomic Research, 9712 Medical Center Drive, Rockville, Maryland 20850, USA
b Department of Microbiology, University of Illinois at Champaign-Urbana, 131 Burrill Hall, 407 South Goodwin, Urabana, Illinois 61801, USA
Archaeoglobus fulgidus is the first sulfate-reducing organism to have its genome completely sequenced. It has a single circular genome with a length of 2,178,400 base pairs, which contains predicted genes for 2439 proteins and 51 stable RNAs. Three- quarters of the predicted protein-encoding genes (1833) were identified by similarity to genes or hypothetical open reading frames previously known in other organisms. About two-thirds of the A. fulgidus genes have counterparts in the genome of M. jannaschii (1). The genes common to both archaea are mainly involved in housekeeping functions, e.g., biosynthesis of amino acids, nucleotides and cofactors, replication and cell division, RNA metabolism, protein synthesis and destination. However, the analysis of the A. fulgidus genome sequence revealed that the two archaea differ more drastically than expected in the way they sense their environment, in their regulatory functions, and in their methods of energy production. In contrast to M. jannaschii, A. fulgidus contains copious amounts of regulatory functions and two- component signal transducing systems which allow a more sensitive recognition and reaction to environmental conditions. A. fulgidus is missing the genes for the two terminal enzymes of the methanogenesis pathway, by which M. jannaschii gains most of its energy from carbon dioxide and hydrogen. The lack of these two enzymes prevents the gain of energy by methanogenesis and is compensated by about 150 additional genes which code for enzymes used in catabolic pathways, e.g. β-oxidation of fatty acids and oxidation of 2-keto acids. Several of these enzymes were previously unknown to the archaea, and some of the genes in these pathways exist in unusually high redundancy of up to 12 copies. The center piece in the energy metabolism of A. fulgidus is acetyl-CoA, the acetyl-component of which is catabolized via a characteristic carbon monoxide dehydrogenase pathway that utilizes the remaining enzymes of the incomplete methanogenesis pathway to produce carbon dioxide and energy. The A. fulgidus genome is also richer than M. jannaschii in genes for transporters, but it contains genes for only one restriction-modification system. In contrast to M. jannaschii, none of the A. fulgidus genes contains inteins.
1. Bult, J.C., White, O., Olsen, G.J., Zhou, L., Fleischmann, R.D., Sutton, G.G., Blake, J.A., FitzGerald, L.M., Clayton, R.A., Gocayne, J.D., Kerlavage, A.R., Dougherty, B.A., Tomb, J.-F., Adams, M.D., Reich, C.I., Overbeek, R., Kirkness, E.F., Weinstock, K.G., Merrick, J.M., Glodek, A., Scott, J.L., Geoghagen, N.S.M., Weidman, J.F., Fuhrmann, J.L., Nguyen, D., Utterback, T.R., Kelley, J.M., Peterson, J.D., Sadow, P.W., Hanna, M.C., Cotton, M.D., Roberts, K.M., Hurst, M.A., Kaine, B.P., Borodovsky, M., Klenk, H.-P., Fraser, C.M., Smith, H.O., Woese, C.R., Venter J.C. (1996) Science, 273, 1058-1073.
