Rhomboid proteases display unique domain combination and novel functions in Haloarchaea.

GIMÉNEZ M.I.; MADRID, E. A.; DE CASTRO R.E.

Puerto Madryn

Congreso; 46° Reunión Anual de la SAIB; 2010

Rhomboids are highly specific intramembrane proteases which are widely conserved in living organisms. Even though they are present in all archaeal genomes sequenced so far, nothing is known on the biology of rhomboid proteases in this domain of life. The aim of our work is to characterize rhomboid proteases in haloarchaea. Mining of haloarchaeal databases showed that all sequenced genomes encode rhomboid protease homologs, some of these contain a canonical six transmembrane segment (TMS) topology whereas others have unique features including extra TMSs or an N-terminal AN-1 Zn-finger motif. In the model haloarchaeon Haloferax volcanii the Zn-finger rhomboid homolog is encoded by the rhoII gene and it is predicted to form and operon with a putative endonuclease V (nfi), potentially involved in DNA repair.By means of RT-PCR we observed that rhoII is expressed at different growth stages in H. volcanii and that it is transcriptionally linked to nfi. We generated a knock-out mutant of the rhoII gene which did not show a differential phenotype in standard growth conditions. However, the mutant strain displayed impaired ability to recover from UV irradiation in minimal medium. Altogether these results show that haloarchaea encode rhomboid proteases with conserved as well as unique features which may play novel physiological roles including DNA repair. Supported by UNMdP and CONICET.