Structural highlights
Publication Abstract from PubMedIn many bacteria, heat shock locus V (HslV) functions as a protease, which is activated by heat shock locus U (HslU). The primary sequence and structure of HslV are well conserved with those of the beta-subunit of the 20S proteasome core particle in eukaryotes. To date, the HslVU complex has only been characterized in the prokaryotic system. Recently, however, the coexistence of a 20S proteasome with HslV protease in the same living organism has been reported. In Trypanosoma brucei, a protozoan parasite that causes human sleeping sickness in Africa, HslV is localized in the mitochondria, where it has a novel function in regulating mitochondrial DNA replication. Although the prokaryotic HslVU system has been studied extensively, little is known regarding its eukaryotic counterpart. Here, we report the biochemical characteristics of an HslVU complex from T. brucei. In contrast to the prokaryotic system, T. brucei possesses 2 potential HslU molecules and we found that only one of them activates HslV. A key activating residue, Tyr494, was identified in HslU2 by biochemical and mutational studies. Furthermore, to our knowledge, this study is the first to report the crystal structure of a eukaryotic HslV, determined at 2.4 A resolution. Drawing on our comparison of the biochemical and structural data, we discuss herein the differences and similarities between eukaryotic and prokaryotic HslVs. Structural and biochemical analyses of the eukaryotic HslV from Trypanosoma brucei.,Sung KH, Lee SY, Song HK J Biol Chem. 2013 Jul 1. PMID:23818520[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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