Characterization of a Protein containing an Ubiquitin-like domain from Natrialba magadii

ORDOÑEZ MV; NERCESSIAN D; CONDE RD

Puerto Madryn

Congreso; XLVI Reunion Anual SAIB; 2010

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Ubiquitin-like proteins and Ubiquitin-like domain containing proteins have been described in both eukaryotes and prokaryotes. This proteins belong to the β-grasp fold characterized by 4-5 antiparallel β-sheets with a middle α-helix region. We are involved in studying the presence of Ubiquitin-like proteins in halophilic archaea. Previously we described the in silico and structural characterization by FTIR of a polypeptide from Natrialba magadii, P400, with structural homology with Ubiquitin-like proteins. The aim of this work was to characterize in silico the protein Nmag_2608 to which P400 region belongs. The Nmag_2608 conserved hypothetical protein of 262 aminoacids belongs to a group of orthologs from different halophilic archaea with no significant sequence similarity to known proteins. Secondary structure prediction showed that they are mainly composed β-sheets structure. Bioinformatic analysis showed that Nmag_2608 and most of its orthologs also contain a signal peptide with a conserved LIPOBOX motif found in bacterial lipoprotein. Finally, we studied the expression of Nmag_2608 in N. magadii cells and a transcript of 1.4 kbps was detected by the specific probe only in the stationary phase of growth. Alltogheter, these results suggest that P400 would be an ubiquitin-like domain inside a membrane anchored protein expressed in late stages of growth of N. magadii cultures. Supported by UNMdP and CONICET.