Impact of a Rhomboid protease knock out mutation on the proteome of the archaeon Haloferax volcanii

CERLETTI, M.; POESTCH, A.; DE CASTRO R.E.; GIMÉNEZ M.I.

Rosario, Santa Fe

Congreso; L Reunión Anual de la SAIB; 2014

Rhomboid proteases are polytopic membrane proteins that perform proteolysis within the hydrophobic environment of the lipid bilayer. Their activity displays and/or releases peptides often involved in cell signaling. To date, only a few rhomboid substrates have been identified. We previously constructed a rhomboid homolog gene (rhoII) deletion mutant in Haloferax volcanii, which evidenced defective protein glycosylation. To better understand the role of RhoII and to identify potential endogenous targets, we used a proteomics approach. Proteome maps of membrane fractions from H. volcanii wt and ΔrhoII strains were obtained by means of tryptic digestion followed by RP-nanoLC-ESI-MS/MS. We identified 1906 proteins which corresponded to 47% of H. volcanii proteome. Of these, at least 29 changed significantly in amount between the parent and mutant strain (1.2 to 28.7 fold). These proteins belonged to various functional categories including protein degradation, oxidative phosphorylation, signal transduction, ion and protein transport. Of the differential proteins, 9 are predicted as integral membrane proteins and may constitute RhoII substrates. Among the differential soluble proteins 2 enzymes involved in protein glycosylation were down-regulated consistent with the phenotype previously observed in the rhoII mutant.