Elucidation of structural determinants
is pivotal for
structure-based
drug discovery. The Farnesoid X receptor (FXR) is a proven target
for NASH; however, its full agonism causes certain clinical complications.
Therefore, partial agonism (PA) appears as a viable alternative for
improved therapeutics. Since the agonist and PA both share the same
binding site, i.e., ligand-binding pocket (LBP), which is highly dynamic
and has synergy with the substrate binding site, the selective designing
of PA is challenging. The identification of structural and conformational
determinants is critical for PA compared with an agonist. Furthermore,
the mechanism by which PA modulates the structural dynamics of FXR
at the residue level, a prerequisite for PA designing, is still elusive.
Here, by using ∼4.5 μs of MD simulations and residue-wise
communication network analysis, we identified the structural regions
which are flexible with PA but frozen with an agonist. Also, the network
analysis identified the considerable changes between an agonist and
PA in biologically essential zones of FXR such as helix H10/H11 and
loop L:H11/H12, which lead to the modulation of synergy between LBP
and the substrate binding site. Furthermore, the thermodynamic profiling
suggested the methionine residues, mainly M328, M365, and M450, seem to be responsible for the recruitment
of PA. The other residues I357, Y361, L465, F308, Q316, and K321 are
also identified, exclusively interacting with PA. This study offers
novel structural and mechanistic insights that are critical for FXR
targeted drug discovery for PA designing.