Structural Dynamics and Functional Analysis of Saprolegnia Parasitica
Chitin Synthases 5 in a Phospholipid Bilayer
Abstract
Saprolegnia parasitica is an oomycete responsible for fish
disease called saprolegniosis, which poses economic and environmental
burden on aquaculture production. Chitin is an essential cell wall
component of S. parasitica synthesized by chitin synthase (CHS)
enzyme. CHSs are large membrane-integrated enzymes with multiple domains
responsible for cellular integration and activation. In saprolegnia,
CHS5 of S. parasitica (SpCHS5) contains an N-terminal domain, a
catalytic domain of the glycosyltransferase -2 family containing a GT-A
fold, and a C-terminal transmembrane domain. In addition, SpCHS5
consists of the MIT (microtubule interacting and trafficking) domain
which is crucial for intracellular trafficking of SpCHS5. There is no
three-dimensional structure of SpCHS5 is reported yet disclosing the
structural details of this protein. We have developed a structural model
of full-length SpCHS5 and validated it by molecular dynamics. This model
structure will assist on designing antiparasitic drug. Structural GT-A
domain and transmembrane contribute stable alpha-helix where MIT domain
demonstrate flexible conformation based on phosphorylation sites. From
the chitin dynamic movement in the protein cavity, we predicted Asp442,
Asp386, Ser541, Tyr379, Asp328, Gln481, Trp485, Tyr645, Thr641, Tyr177
residues as a prominent cavity lining site. Overall, this present work
will be helpful to understand the biochemistry of CHS5 and design
inhibitors against SpCHS5.