Mass spectrometric analysis of proteolytic cleavage related to ArtA and PssA from Haloferax volcanii

The S-layer glycoprotein (SLG) of Haloferax volcanii has been shown to be processed and C-terminally linked to a lipid in an archaeosortase A (ArtA)-dependent manner. A C-terminal tripartite structure including a PGF motif is required for the processing of SLG as well as other substrates (Abdul Halim et al., 2013 Mol Microbiol; Abdul Halim et al., 2016 J Bact; Abdul Halim et al., 2017 J Bact; Abdul Halim et al., 2018 Mol Microbiol). In order to gain insights into the mechanism of processing, different cellular fractions (culture supernatant, membrane) from different strains (WT, ArtA KO mutant, ArtA active site mutants, PssA KO mutant) have been analyzed. C-terminal peptides of SLG as well as peptides spanning the PGF motiv were only identified in the mutants lacking processing activity.