Substrate recognition and cleavage-site preferences of Lon protease

Area of Science:

• Molecular Biology
• Proteomics
• Bacterial Physiology

Background:

• The AAA+ Lon protease is crucial for maintaining protein homeostasis by degrading misfolded, damaged, or regulatory proteins.
• Protein degradation by Lon protease involves substrate recognition (degrons), unfolding/translocation, and cleavage.
• Broad rules for Lon substrate recognition and cleavage site preferences across bacterial species remain largely unknown.

Purpose of the Study:

• To identify broadly applicable rules governing Lon protease substrate recognition.
• To characterize novel Lon protease recognition motifs (degrons) and their distribution.
• To determine the cleavage-site preferences of the Lon protease domain.

Main Methods:

• Identification and characterization of C-terminal recognition degrons in Yersinia pestis.
• Bioinformatic analysis of degron distribution in diverse bacterial species.
• Cleavage-site preference analysis of multiple Lon protease substrates.

Main Results:

• Discovery of a class of high-affinity, autonomous C-terminal Yersinia pestis Lon recognition degrons.
• Demonstration that these degrons are present in known and novel Yersinia pestis substrates and distributed across diverse bacteria.
• Identification of a conserved Lon protease cleavage preference for phenylalanine residues, producing peptides of 7–35 residues (average 11).

Conclusions:

• The identified degron group provides predictive power for discovering new bacterial Lon protease substrates.
• The conserved phenylalanine cleavage preference suggests a general mechanism for Lon protease activity across bacterial species.
• This work advances the understanding of bacterial protein turnover and homeostasis regulation.