Combination
of Genetic Screening and Molecular Dynamics
as a Useful Tool for Identification of Disease-Related Mutations:
ZASP PDZ Domain G54S Mutation Case
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Abstract
Cypher/ZASP
(<i>LDB3</i> gene) is known to interact with
a network of proteins. It binds to α-actinin and the calcium
voltage channels (LTCC) via its PDZ domain. Here we report the identification
of a highly conserved ZASP G54S mutation classified as a variant of
unknown significance in a sample of an adult with hypertrophic cardiomyopathy
(HCM). The initial bioinformatics calculations strongly evaluated
G54S as damaging. Furthermore, we employed accelerated and classical
molecular dynamics and free energy calculations to study the structural
impact of this mutation on the ZASP apo form and to address the question
of whether it can be linked to HCM. Seventeen independent MD runs
and simulations of 2.5 μs total were performed and showed that
G54S perturbs the α2 helix position via destabilization of the
adjacent loop linked to the β5 sheet. This also leads to the
formation of a strong H-bond between peptide target residues Leu17
and Gln66, thus restricting both the α-actinin2 and LTCC C-terminal
peptides to access their natural binding site and reducing in this
way their binding capacity. On the basis of these observations and
the adult’s clinical data, we propose that ZASP<sup>G54S</sup> and presumably other ZASP PDZ domain mutations can cause HCM. To
the best of our knowledge, this is the first reported ZASP PDZ domain
mutation that might be linked to HCM. The integrated workflow used
in this study can be applied for the identification and description
of other mutations that might be related to particular diseases