Proteolytic Activity and Substrate Specificity of Lake Geneva

Area of Science:

• Environmental microbiology
• Biochemistry
• Protease activity in aquatic ecosystems

Background:

• Microbial proteases in lakewater are crucial for organic matter cycling and contaminant degradation.
• The specific identities and substrate preferences of these proteases remain largely uncharacterized.

Purpose of the Study:

• To determine the global proteolytic fingerprint of extracellular proteases in Lake Geneva.
• To investigate the substrate specificities and identify the types of proteases present in lakewater.

Main Methods:

• Multiplex Substrate Profiling by Mass Spectrometry (MSP-MS) was employed to analyze cleavage sites.
• Class-specific inhibitors were used to identify protease classes involved in proteolytic activity.

Main Results:

• A trypsin-like substrate specificity was dominant, with preferred cleavage near arginine and lysine residues.
• This specificity was conserved across seasons and depths, and in other Swiss lakes.
• Serine and metalloproteases were identified as key contributors to both exo- and endoproteolytic activities.

Conclusions:

• The study reveals conserved and variable aspects of protease substrate specificity in lakewater ecosystems.
• Findings enhance understanding of protein stability and the environmental fate of peptidic contaminants.