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@ARTICLE{delCaoOchoa:619752,
author = {del Caño-Ochoa, Francisco and Grande-García, Araceli and
Reverte-López, María and D’Abramo, Marco and
Ramón-Maiques, Santiago},
title = {{C}haracterization of the catalytic flexible loop in the
dihydroorotase domain of the human multi-enzymatic protein
{CAD}},
journal = {Biologist},
volume = {293},
number = {49},
issn = {0021-9258},
address = {Bethesda, MD},
publisher = {American Soc. for Biochemistry and Molecular Biology},
reportid = {PUBDB-2024-07887},
pages = {18903-18913},
year = {2018},
note = {ISSN 0021-9258 not unique: **2 hits**.},
abstract = {The dihydroorotase (DHOase) domain of the multifunctional
protein carbamoyl-phosphate synthetase 2, aspartate
transcarbamoylase, and dihydroorotase (CAD) catalyzes the
third step in the de novo biosynthesis of pyrimidine
nucleotides in animals. The crystal structure of the DHOase
domain of human CAD (huDHOase) revealed that, despite
evolutionary divergence, its active site components are
highly conserved with those in bacterial DHOases, encoded as
monofunctional enzymes. An important element for catalysis,
conserved from Escherichia coli to humans, is a flexible
loop that closes as a lid over the active site. Here, we
combined mutagenic, structural, biochemical, and molecular
dynamics analyses to characterize the function of the
flexible loop in the activity of CAD's DHOase domain. A
huDHOase chimera bearing the E. coli DHOase flexible loop
was inactive, suggesting the presence of distinctive
elements in the flexible loop of huDHOase that cannot be
replaced by the bacterial sequence. We pinpointed Phe-1563,
a residue absolutely conserved at the tip of the flexible
loop in CAD's DHOase domain, as a critical element for the
conformational equilibrium between the two catalytic states
of the protein. Substitutions of Phe-1563 with Ala, Leu, or
Thr prevented the closure of the flexible loop and
inactivated the protein, whereas substitution with Tyr
enhanced the interactions of the loop in the closed position
and reduced fluctuations and the reaction rate. Our results
confirm the importance of the flexible loop in CAD's DHOase
domain and explain the key role of Phe-1563 in configuring
the active site and in promoting substrate strain and
catalysis.},
cin = {EMBL-User},
ddc = {610},
cid = {I:(DE-H253)EMBL-User-20120814},
pnm = {6G3 - PETRA III (DESY) (POF4-6G3) / BIOSTRUCT-X -
Transnational access and enhancement of integrated
Biological Structure determination at synchrotron X-ray
radiation facilities (283570)},
pid = {G:(DE-HGF)POF4-6G3 / G:(EU-Grant)283570},
experiment = {EXP:(DE-H253)P-P13-20150101},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:30315107},
UT = {WOS:000458467400008},
doi = {10.1074/jbc.RA118.005494},
url = {https://bib-pubdb1.desy.de/record/619752},
}