Study on the Interaction Mechanism between Phospholipase A1 from
Serratia marcescens and Its Auxiliary Proteins Based on Molecular
Docking
Abstract
Previous studies showed a sequence encoding an auxiliary protein (PlaS)
downstream of the phospholipase A1 (PlaA1) gene of Serratia
marcescens. There is an interaction between PlaA1 and PlaS, which may
be closely related to the high enzymatic activity property of
phospholipase A1. In order to further investigate the interaction
mechanism, it is necessary to explore binding sites of the interaction
between PlaA1 and PlaS and the regulatory mechanism for enzymatic
properties by molecular docking and site-directed mutagenesis. The
results showed that the active center site of PlaA1 was encapsulated
internally, and a “catalytic pocket” was formed externally by
Leu197-Ser249. The docking process of PlaA1 and PlaS involved 29 and 30
amino acids, respectively, of which Phe186 and Lys238 of PlaA1 are
involved in forming π-bonds and multiple hydrogen bonds. Therefore,
Phe186 and Lys238 were site-directed mutated to Ala to obtain the mutant
enzymes PlaA1 F186A and PlaA1 K238A,
respectively. The results showed that the mutant enzymes showed no
significant changes in optimum temperature and pH but poor stability.
The kinetic parameters indicated that the affinity between PlaA1 and
substrates was weakened, and the catalytic efficiency was reduced after
mutation. Therefore, it demonstrated that Phe186 and Lys238 of PlaA1
provided non-covalent bonds conducive to the enzymatic activity and
stability in the interaction between PlaA1 and PlaS, which would provide
some theoretical basis for further rational design and modification of
phospholipase A1 subsequently.