Reverse Gyrase from the Hyperthermophilic Bacterium Thermotoga maritima: Properties and Gene Structure

AUTOR(ES)

de la Tour, Claire Bouthier

FONTE

American Society for Microbiology

RESUMO

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°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 ω-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.

Documentos Relacionados

• Both DNA gyrase and reverse gyrase are present in the hyperthermophilic bacterium Thermotoga maritima
• Thermostable chemotaxis proteins from the hyperthermophilic bacterium Thermotoga maritima.
• Properties and gene structure of the Thermotoga maritima alpha-amylase AmyA, a putative lipoprotein of a hyperthermophilic bacterium.
• Structure of a d-tagatose 3-epimerase-related protein from the hyperthermophilic bacterium Thermotoga maritima
• Aspartate Transcarbamylase from the Hyperthermophilic Eubacterium Thermotoga maritima: Fused Catalytic and Regulatory Polypeptides Form an Allosteric Enzyme