Serratiopeptidase exhibits antibiofilm activity through the proteolytic function of N-terminal domain and versatile function of the C-terminal domain

Abstract

Background: Serratiopeptidase, a serine protease traditionally used as an oral anti-inflammatory drug has been found to show antibiofilm action. Structurally, it comprises of two distinct domains; viz-the N-terminal catalytic domain (Ncat) and a C-terminal RTX (Repeat-In-Toxin) domain (Crtx). Understanding the antibiofilm action of the serratiopeptidase molecule, as well as the antibiofilm action of each of its two domains, was the objective of this study.

Results: Separate clones to express the complete recombinant serratiopeptidase protein and its variant containing a mutation in the catalytic site, the N-terminal catalytic domain and its mutant, and the C-terminal Repeat-In-Toxin domain were prepared, and the proteins were purified. The impact of these proteins on pre-existing biofilms, as well as their effect upon addition of these proteins during biofilm formation was investigated.

Conclusions: In our investigation, we have been able to analyze the antibiofilm action of serratiopeptidase in detail. Obtained results conclude that while N-terminally located proteolytic domain of serratiopeptidase conventionally acts against biofilms by hydrolytic activity, the C-terminal domain regulates or prevents biofilm formation by yet unknown mechanism in addition to its known function as an C-terminal located calcium modulated internal chaperone ensuring the proper folding and secretion of the molecule. The study's findings give new evidence that the Crtx domain plays a significant role in antibiofilm action. The proteolytic Ncat domain breaks down pre-formed biofilms. The C-terminal domain, on the other hand, acts as an inhibitor of biofilm formation by regulating or preventing biofilm development.

Keywords: Antibiofilm activity; Biofilm; C-RTX domain; Genetic engineering; N-terminal catalytic domain; Proteolysis; Serratia marcescens; Serratiopeptidase.