Halophilic bacteria Salinibacter ruber exhibit reactive proteins against anti-ubiquitin antibody

BONADERO, M.C.; CONDE, R.D.; NERCESSIAN, D.

Puerto Madryn

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Although ubiquitin is a key and conserved protein present only in eukaryotes, all domains of life contain ubiquitin-like proteins (Ubls) sharing similar folding and role with ubiquitin. Previously, we found several proteins that react with anti-ubiquitin antibody in halophilic archaea. The present work analyzed whether the halophilic bacteria Salinibacter ruber, as belonging to a different life domain, also posses Ubls. For this, protein extracts from S. ruber cells were separated by 2D SDS-PAGE and subjected to Western blot using a polyclonal anti-ubiquitin antibody. Samples from the different growth phases displayed immune-reactive spots ranging from 51 to 112 kDa and pI 5-6. The spots were excised from the gel and subjected to protein sequence determination by MS of the tryptic fragments. The analysis of the obtained sequences showed that most of them are membrane proteins and some display a TonB-dependent receptor domain. A further analysis of some of the MS peaks showed that they matched with the small hypothetical protein SRU_2854. Although the statistical limits were not enough significant, SRU_2854 has a di-glycine motif at its Ct, as ubiquitin and Ubls. Also sequence alignment and structure prediction studies showed similarities to some Ubls. This protein could be interacting with a major protein that could be the recognized by the antibody. Supported by CONICET and UNMdP.