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Journal of Bacteriology, March 2000, p. 1609-1615, Vol. 182, No. 6
Laboratory for Genetics and Microbiology,
Vrije Universiteit Brussel (VUB), and Department of Microbiology,
Flanders Interuniversity Institute for
Biotechnology,1 and Jean-Marie Wiame
Institute for Microbiological Research,2 B-1070
Brussels, Belgium, and Alfred-Wegener-Institut für Polar-
und Meeresforschung, D-27570 Bremerhaven, Germany3
Received 22 September 1999/Accepted 23 December 1999
In the arginine biosynthetic pathway of the vast majority of
prokaryotes, the formation of ornithine is catalyzed by an enzyme transferring the acetyl group of N-
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Evolution of Arginine Biosynthesis in the Bacterial
Domain: Novel Gene-Enzyme Relationships from Psychrophilic
Moritella Strains (Vibrionaceae) and
Evolutionary Significance of N-
-Acetyl
Ornithinase
-acetylornithine to
glutamate (ornithine acetyltransferase [OATase]) (argJ
encoded). Only two exceptions had been reported
the
Enterobacteriaceae and Myxococcus xanthus
(members of the
and
groups of the class
Proteobacteria, respectively)
in which ornithine is
produced from N-
-acetylornithine by a deacylase,
acetylornithinase (AOase) (argE encoded). We have investigated the gene-enzyme relationship in the arginine regulons of
two psychrophilic Moritella strains belonging to the
Vibrionaceae, a family phylogenetically related to the
Enterobacteriaceae. Most of the arg genes were
found to be clustered in one continuous sequence divergently
transcribed in two wings, argE and argCBFGH(A) ["H(A)" indicates that the argininosuccinase gene
consists of a part homologous to known argH sequences and
of a 3' extension able to complement an Escherichia coli
mutant deficient in the argA gene, encoding
N-
-acetylglutamate synthetase, the first enzyme
committed to the pathway]. Phylogenetic evidence suggests that this
new clustering pattern arose in an ancestor common to Vibrionaceae and Enterobacteriaceae, where
OATase was lost and replaced by a deacylase. The AOase and ornithine
carbamoyltransferase of these psychrophilic strains both display
distinctly cold-adapted activity profiles, providing the first
cold-active examples of such enzymes.
*
Corresponding author. Mailing address: Laboratory for
Genetics and Microbiology, Vrije Universiteit Brussel (VUB), and
Department of Microbiology, Flanders Interuniversity Institute for
Biotechnology, 1, E. Gryson Ave., B-1070 Brussels, Belgium. Phone:
32-2-526 72 75. Fax: 32-2-526 72 73. E-mail:
ceriair{at}ulb.ac.be.
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