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J. Bacteriol., 01 1998, 274-281, Vol 180, No. 2
C Bouthier de la Tour, C Portemer, H Kaltoum and M Duguet
The hyperthermophilic bacterium Thermotoga maritima MSB8 possesses a
reverse gyrase whose enzymatic properties are very similar to those of
archaeal reverse gyrases. It catalyzes the positive supercoiling of the DNA
in an Mg2+- and ATP-dependent process. Its optimal temperature of activity
is around 90 degrees C, and it is highly thermostable. We have cloned and
DNA sequenced the corresponding gene (T. maritima topR). This is the first
report describing the analysis of a gene encoding a reverse gyrase in
bacteria. The T. maritima topR gene codes for a protein of 1,104 amino
acids with a deduced molecular weight of 128,259, a value in agreement with
that estimated from the denaturing gel electrophoresis of the purified
enzyme. Like its archaeal homologs, the T. maritima reverse gyrase exhibits
helicase and topoisomerase domains, and its sequence matches very well the
consensus sequence for six reverse gyrases now available. Phylogenetic
analysis shows that all reverse gyrases, including the T. maritima enzyme,
form a very homogeneous group, distinct from the type I 5' topoisomerases
of the TopA subfamily, for which we have previously isolated a
representative gene in T. maritima (topA). The coexistence of these two
distinct genes, coding for a reverse gyrase and an omega-like
topoisomerase, respectively, together with the recent description of a
gyrase in T. maritima (O. Guipaud, E. Marguet, K. M. Noll, C. Bouthier de
la Tour, and P. Forterre, Proc. Natl. Acad. Sci. USA 94:10606-10611, 1977)
addresses the question of the control of the supercoiling in this organism.
Copyright © 1998, American Society for Microbiology
Reverse gyrase from the hyperthermophilic bacterium Thermotoga maritima: properties and gene structure [In Process Citation]
Laboratoire d'Enzymologie des Acides Nucleiques, Institut de Genetique et Microbiologie, Universite Paris-Sud, Orsay, France. bouthier@igmors.u-psud.fr
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