Deletion of rhomboid protease gene affects protein glycosilation and cell morphology in H. volcanii

GIMENEZ, M.I.; PAGGI, R. A.; DE CASTRO R.E.

Congreso; 47° Reunión Anual de la SAIB; 2011

Rhomboids (Rho) are a recently discovered family of widely distributed intramembrane serine proteases. In eukaryotes and bacteria these enzymes have diverse biological functions including regulation of growth factor signalling, mitochondrial fusion, parasite invasion and quorum sensing. However, nothing is known on the biology of Rho proteases in Archaea. The aim of our research is to characterize archaeal Rho using Haloferax volcanii as a model organism. To identify possible Rho substrates, we compared SDS-PAGE profiles of wt and a Rho protease (rhoII) deletion mutant (MIG1). Protein staining evidenced two polypeptides (200 and 98 kDa, respectively) that were enriched in the membrane fraction of the mutant strain MIG1. By LC-MS/MS analysis, these species were identified as the S-layer glycoprotein (200 kDa) and a putative periplasmic substrate-binding protein (98 kDa) of a dipeptides/oligopeptides ABC transporter. PAS staining confirmed that both polypeptides were glycosilated and revealed a different electrophoretic profile of glycosilated species in the wt compared to MIG1. In accordance with defective glycosilation of the S-layer protein, cell shape was affected in the mutant strain, as observed by SEM. Altogether our results suggest that RhoII may be involved in regulation of the protein glycosilation pathway in haloarchaea. Supported by ANPCyT, UNMdP and CONICET.