Involvement of a haloarchaeal rhomboid protease in cell adhesion and motility regulation

MARIANA INES COSTA; MICAELA CERLETTI; CHRISTIAN TROETSCHEL; ANSGAR POETSCH; ROSANA ESTHER DE CASTRO; MECHTHILD POHLSCHRODER; ROBERTO ALEJANDRO PAGGI; MARÍA INÉS GIMÉNEZ

Buenos Aires

Congreso; LIII Reunión anual SAIB; 2017

Rhomboids are a family of intramembrane serine proteases represented in the three Domains of Life. These enzymes participate in gene regulation and cellular signalling in eukaryotes, but little is known about their targets in prokaryotes, such as Archaea. Our previous work showed that deletion of one of the two Rhomboid protease genes (rhoII) has a global effect on the proteome of the haloarchaeon Haloferax volcanii (membrane and cytoplasm fractions). In addition, some putative RhoII targets (direct or indirect) were identified, including pilin pilA1, prepilin/preflagellin peptidase PibD and PrsW protease. To validate these results in this work we analysed PibD and PrsW processing in H. volcanii wild type (H26) and ΔrhoII (MIG1). An in vivo assay suggested that the differences in PrsW level (29 fold reduction) previously observed in MIG1 may be due to an indirect effect of the rhoII mutation. On the other hand, preliminary Western blotting analysis of H. volcanii H26 and MIG1 membrane samples, indicated that PibD may be processed in a RhoII dependent manner. Overexpression of PibD natural substrates (pilins 1-6) in H26 and MIG1 strains showed differences in the amount of these proteins in cell extracts and culture supernatants, suggesting that they may be indirectly affected by RhoII.With the aim of completing the initial proteomic study we also analysed and compared the secretomes of H26 and MIG1. We identified 27 differentially represented proteins, including some involved in motility and cell adhesion, such as flagellin1 and the hypothetical protein HVO_1533. Taken together, our results suggest that RhoII regulates cell adhesion and motility, likely by processing PibD and subsequently affecting the functioning or assembly of pili and/or flagella in H. volcanii.