Characterization of the Rho protein of the fungus Mucor rouxii

GALELLO, F., ARGIMON, S., PEREYRA, E., ROSSI, S. AND MORENO, S

Iguazu, Misiones

Congreso; XL Reunion Anual de SAIB; 2004

SAIB

Cell polarity is central to cell function, acting to organise the biochemistry and the structures that result in the development of cells with specialised physiology. The Rho family of GTPases, particularly RhoA, have emerged as central coordinators of a remarkable variety of cellular functions including cytoskeletal organization. RHOI gene ITom Mrouxii has been cloned and the deduced amino acid sequence has highest homology with S. pombe (88%) and human RhoA (80%). The 3D structure of Mrouxii Rholp was obtained by molecular modelling through the Swiss­model protein modeIling server using as template the coordinates of crystallized human RhoA.The overall structure is conserved. The expression ofRholp was confirmed by ADP-ribosylation and cytoimmunofluorescence. Rho 1 p has a differential expression during germination as was detected by Westem-blot and RT-PCR. The Mrouxii RHOI gene could rescue a S.cerevisiae strain containing a rhoI deletion. Rholp in S.cerevisiae was identify as the regulatory subunit of _-I ,3-glucan synthase. Vegetative Mrouxii cell wall does not have a significant amount of glucans however caspofungin an antifungal agent which inhibits the synthesis of _-l ,3-glucan has an important effect on morphology and growth. The MEC (minimum effective concentrationnecessary to observe morphological changes) was 10llg/ml similar to that in Aspergillus spp and Fusarium spp suggesting that Rho 1 p of Mrouxii could regulate _-1,3-glucan synthesis.