Presence of structural homologs of ubiquitin in haloalkaliphilic Archaea Authors Débora Nercessian Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Cristina Marino Buslje Institute of Chemistry and Physicochemical Biology, Faculty of Pharmacy and Biochemistry, National University of Buenos Aires and CONICET, Buenos Aires, Argentina María V. Ordóñez Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Rosana E. De Castro Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Rubén D. Conde Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Keywords: Natrialba magadii, halophilic archaea, ubiquitin-like proteins, structural homology Abstract Ubiquitin, a protein widely conserved in eukaryotes, is involved in many cellular processes, including proteolysis. While sequences encoding ubiquitin-like proteins have not been identified in prokaryotic genomes sequenced so far, they have revealed the presence of structural and functional homologs of ubiquitin in Bacteria and Archaea. This work describes the amplification and proteomic analysis of a 400-bp DNA fragment from the haloalkaliphilic archaeon Natrialba magadii. The encoded polypeptide, P400, displayed structural homology to ubiquitin-like proteins such as those of the ThiS family and Urm1. Expression of the P400 DNA sequence in Escherichia coli cells yielded a recombinant polypeptide that reacted with anti-ubiquitin antibodies. In addition, a putative open reading frame encoding P400 was identified in the recently sequenced genome of N. magadii. Together, these results evidence the presence in Archaea of structural homologs of ubiquitin- related proteins. [Int Microbiol 2009; 12(3):167-173] Author Biographies Débora Nercessian, Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Cristina Marino Buslje, Institute of Chemistry and Physicochemical Biology, Faculty of Pharmacy and Biochemistry, National University of Buenos Aires and CONICET, Buenos Aires, Argentina Institute of Chemistry and hysicochemical Biology, Faculty of Pharmacy and Biochemistry, National University of Buenos Aires and CONICET, Buenos Aires, Argentina María V. Ordóñez, Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Rosana E. De Castro, Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Rubén D. Conde, Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Institute of Biological Research, Faculty of Exact and Natural Sciences, National University of Mar del Plata and CONICET, Mar del Plata, Argentina Downloads PDF Published 2010-01-14 Issue Vol. 12 No. 3 (2009) Section Research Articles License Submission of a manuscript to International Microbiology implies: that the work described has not been published before, including publication in the World Wide Web (except in the form of an Abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that all the coauthors have agreed to its publication. 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