In Silico Structural Analysis of the Grapevine Serine Protease VviSBT4.19 Involved in Defense against P. viticola

Grapevine pathogens, such as Plasmopara
viticola, a downy mildew disease-causing agent, pose
a significant threat
to grape and wine production worldwide. Molecular details are needed
on how tolerant grapevine species recognize and mount a successful
defense response against this pathogen. We have identified the important
role of grapevine subtilase VviSBT4.19; however, without a reliable
structural model, we have a limited understanding of protease activity
modulation by P. viticola. Here, we
built a consensus computational model of this protein and performed
constant-pH MD simulations to assess its overall structural stability.
We identified Ser419 as the key residue in autocatalytic processing
and demonstrated that its S419N mutation produces a stable, active
protease with a reduced autocatalytic activity. This work provides
the first reliable structural model of VviSBT4.19, offering crucial
insights into its function and regulation and opening new avenues
for engineering enhanced disease resistance in grapevine cultivars.