Abstract:
Cytochrome P450 monooxygenases (P450s)
are ubiquitous heme-thiolate proteins that have potential
biotechnological application. Thermostable-P450s that can
withstand hostile industrial conditions, such as high temperatures,
extremes of pH and organic solvents, are needed
for biotechnological usage. Here, for the first time, we
report a large number of thermostable-P450s from two
thermophilic biomass-degrading fungi, Myceliophthora
thermophila and Thielavia terrestris. Genome-wide P450
analysis revealed the presence of 79 and 70 P450s
(P450ome) in T. terrestris and M. thermophila. Authentic
P450s containing both the P450 signature domains (EXXRand CXG) were classified as follows: T. terrestris (50
families and 56 subfamilies) and M. thermophila (49
families and 53 subfamilies). Bioinformatics analysis of
P450omes suggested the presence of a large number of
thermostable-P450s. Based on aliphatic index cut-off
([90), 14 and 11 P450s were determined to be thermostable
in T. terrestris and M. thermophila. Among the
thermostable P450s, six P450s from T. terrestris and three
from M. thermophila had a melting temperature (Tm) of
[65 C, suggesting their hyperthermal tolerance. Analysis
of the instability index of two ascomycete P450omes
revealed the presence of 12 and 19 in vitro stable P450s in
T. terrestris and M. thermophila. Overall, six P450s from
T. terrestris and four from M. thermophila showed both
thermal tolerance and in vitro stability. Thermophilic
ascomycetes P450s are of potential interest from a structural,
mechanistic and biotechnological point of view, as
five P450s showed higher thermal tolerance and five
showed higher in vitro stability compared to the wellcharacterized
thermostable-P450s CYP175A1 (bacteria)
and CYP119 (archaea).
