Biotechnological Applications of Thermus thermophilus as Host
Aurelio Hidalgo and José Berenguer
Affiliation: Centro de Biología Molecular Severo Ochoa. Facultad de Ciencias. Universidad Autónoma de Madrid Madrid, 28049, Spain.
Keywords: Expression vectors, selection markers, thermophiles, thermoselection, thermostability thermozymes.
Thermostability is a desired property for the biotechnological use of enzymes as it increases the half-life of the
enzyme, facilitates its transport and conservation, and is associated to additional resistance against the action of detergents
and organic solvents. The availability of thermostable enzymes depends either on the discovery of the appropriate enzyme
from a thermophilic microorganism or in the isolation of thermostable variants of a thermo-sensitive enzyme that
catalyzes the desired reaction. In the first case the overproduction of the enzyme is attempted in well-known mesophilic
hosts. As only low percentage of the genes encoded by thermophiles can be expressed in such hosts, the development of
appropriate thermophilic hosts is required. Among extreme thermophilic bacteria, a complete genetic toolbox has been
developed only for Thermus thermophilus, in such a way that this organism can be used as cell factory for the
recombinant production of thermophilic proteins at their natural temperatures. Plasmids, thermostable resistances to
antibiotics, reporters, and available promoters are reviewed that can be used for protein expression at high temperatures.
Tools developed for the direct selection of thermostable variants of mesophilic proteins by protein folding interference in
T. thermophilus are also described.
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