Abstract
Multi-antimicrobial extrusion (MATE) transporter membrane proteins
provide drug and toxin resistivity by expelling compounds from cells.
MATE proteins can be pictured as V-shaped. To regulate its functioning,
the protein structure can switch between outward-facing (OF) and
inward-facing (IF). Pyrococcus furiosus MATE (PfMATE) is the only
member of the multidrug/oligosaccharidyl-lipid/polysaccharide (MOP)
superfamily that has available both the IF and OF crystal structures.
With the availability of the both the IF and OF structures, we are able
to perform computational investigations to determine how protonation of
specific amino acids causes a cascade of changes in the protein
conformation that allow PfMATE to change its state from OF to IF in
order to regulate its antiporter function. Using a variety of
computational techniques, we investigated four different systems of IF
and OF PfMATE along with the native archaeal lipid bilayer, without or
with protonation at the experimentally determined locations within the
protein. We performed molecular dynamics (MD) simulations to investigate
the flexibility of the four different PfMATE structures, and also
performed targeted molecular dynamics (TMD) simulations during which we
observe occluded conformations. Our analysis of hydrogen bond changes,
potential of mean force, dynamic network analysis, and transfer entropy
analysis provides information on how protonation can induce cascading
structural changes responsible for the transition between the IF and OF
configurations.