Updated FTP location. The proteome turnover was examined in a conditional LonB mutant (HVLON3) of the model euryarchaeon H. volcanii under reduced (- trp) and nearly physiological (+ trp) LonB levels. HVLON3 was initially grown in minimal medium containing 14NH4Cl as nitrogen source in absence of trp and then switched to 15N-medium with/without trp (± Lon) to monitor 15N-label incorporation into newly synthesized proteins over time. In parallel, degradation of 14N-labeled proteins was estimated by comparing different time points of this culture via an internal standard grown on 13C-glucose. Protein samples (membrane and cytoplasm fractions) were processed by SDS-PAGE, digested with trypsin and analyzed by LC-MS/MS. Proteins were identified with Sequest and protein turnover, as well as statistical analysis, was achieved with the online platform QuPE. In addition, an in vivo crosslinking assay coupled to immunoprecipitation with anti-Lon antibody was performed in the H. volcanii H26 wt strain to detect interactions between LonB and its endogenous targets.