Abstract
Background: The ribosomal stalk composed of P-proteins constitutes a structure on the large ribosomal particle responsible for recruitment of translation factors and stimulation of factor-dependent GTP hydrolysis during translation. The main components of the stalk are P-proteins, which form a pentamer. Despite the conserved basic function of the stalk, the P-proteins do not form a uniform entity, displaying heterogeneity in the primary structure across the eukatyotic lineage. The P-proteins from protozoan parasites are among the most evolutionarily divergent stalk proteins.
Methods: We have assembled P-stalk complex of Plasmodium faldparum in vivo in bacterial system using tricistronic expression cassette and provided its characteristics by biochemical and biophysical methods.
Results: All three individual P-proteins, namely uLl 0/P0, P1 and P2, are indispensable for acquisition of a stable structure of the P stalk complex and the pentameric uL10/P0-(P1-P2)(2) form represents the most favorable architecture for parasite P-proteins.
Conclusion: The formation of P. faldparum P-stalk is driven by trilateral interaction between individual elements which represents unique mode of assembling, without stable P1-P2 heterodimeric intermediate.
General significance: On the basis of our mass-spectrometry analysis supported by the bacterial two-hybrid assay and biophysical analyses, a unique pathway of the parasite stalk assembling has been proposed. We suggest that the absence of P1/P2 heterodimer, and the formation of a stable pentamer in the presence of all three proteins, indicate a one-step formation to be the main pathway for the vital ribosomal stalk assembly, whereas the P2 homo-oligomer may represent an off-pathway product with physiologically important nonribosomal role. (C) 2014 Elsevier B.V. All rights reserved.