Leishmania donovani HslV does not interact stably with HslU proteins

Genes for HslVU-type peptidases are found in bacteria and in a few select Eukaryota, among those such important pathogens as Plasmodium spp. and Leishmania spp. In this study, we performed replacements of all three HslV/HslU gene homologues and found one of those, HslV, to be essential for Leishmania donovani viability. The Leishmania HslV gene can also partially relieve the thermosensitive phenotype of a combined HslVU/Lon/ClpXP knockout mutant of Escherichia coli, indicating a conserved function. However, we found that the role and function of the two Leishmania HslU genes has diverged since neither of those interacts stably with HslV. The latter forms a dodecameric complex by itself and shows a punctate distribution. We conclude that whilst the basic function of HslV may be conserved in Leishmania, its organisation and interaction with its canonical complex partner HslU is not. Nevertheless, given the absence of HslV from the proteome of mammals and its essential role in Leishmania viability, HslV is a promising target for intervention.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (40 K)Download as PowerPoint slideHighlights► The prokaryotic protease HslV is essential for Leishmania donovani in vitro. ► Unlike its bacterial counterparts, Leishmania HslV is not associated with HslU type regulatory subunits. ► Leishmania HslV is capable of complementing Escherichia coli HslVU null-mutants. ► The findings make HslV a candidate drug target.