Archaeal genomics: Do archaea have a mixed heritage?
W. Ford Doolittle and John M. Logsdon, Jr.
A third complete archaeal genome sequence, replete
with eukaryote-like genes for replication, transcription
and translation, has appeared. The sequence also
shows bacteria-like features. It is time to come to grips
with this evidence for a mixed heritage.
Address: Program in Evolutionary Biology, Canadian Institute for
Advanced Research, Department of Biochemistry, Dalhousie
University, Halifax, Nova Scotia, Canada B3H 4H7.
Current Biology 1998, 8:R209–R211
© Current Biology Ltd ISSN 0960-9822
Completed microbial genome sequences are like books that
we have paid for and brought home from the shop, but have
not had time to read. Dauntingly, there are already a dozen
of them on the shelf, according to the website
(http://www.tigr.org) of The Institute
Research. Three of these complete genome sequences are
for archaeal (archaebacterial) species, the latest being that of
Archaeoglobus fulgidis, published recently by Klenk et al. .
Readers may recall that, in 1993, the otherwise obscure
archaeal genus Archaeoglobus was the subject of a scary
paper entitled “Hyperthermophilic archaea are thriving in
deep North Sea and Alaskan oil reservoirs” . These
pressure-tolerant organisms, with temperature optima
between 80°C and 90°C, grow organo-heterotrophically on
a variety of carbon and energy sources, reducing sulphate
to sulphide, and “souring” oil wells. Although this makes
Archaeoglobus a sort of petrochemical pathogen, it is not the
economic impact of this or the other two archaea for which
complete genome sequences have been published — the
methanogens Methanococcus jannaschii  and Methanobac-
terium thermoautotrophicum  — that makes them espe-
cially interesting. Rather, it is their thermophily, their
unique energy metabolism, and (in the main) their pivotal
position in our current understanding of cellular evolution.