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 found in both eukaryotes and prokaryotes. They belong to the β-grasp fold characterized by 4-5 antiparallel β-sheets with a middle α-helix region. Searching for the presence of Ubls in halophilic archaea, we previously found by both in silico and FTIR analysis that P400, a polypeptide from Natrialba magadii, displays structural homology with Ubiquitin-like proteins. The aim of this work was to characterize the Nmag_2608 protein that includes P400. This conserved hypothetical protein of 262 amino acids is part of a group of orthologs from different halophilic archaea with no significant sequence likeness to known proteins. Secondary folding prediction showed that they are mainly composed by β-sheets. Also, bioinformatics analysis predicted that Nmag_2608 and most of its orthologs contain a signal peptide with a conserved LIPOBOX motif found in bacterial lipoproteins. Lastly, expression of Nmag_2608 in N. magadii cells allowed to detect, only in the stationary phase of growth, a 1.4 kbps transcript. All together, these results suggest that P400 is an Ubiquitin-like domain inside a membrane anchored protein expressed in N. magadii at late stages of growth. Supported by UNMdP and CONICET.