Abstract
The eukaryotic 60S-ribosomal stalk is composed of acidic ribosomal proteins (P1 and P2) and neutral protein P0, which are thought to be associated as a pentameric structure, [2P1, 2P2, P0]. Plasmodium falciparum P2 (PfP2) appears to play additional non-ribosomal functions associated with its tendency for homo-oligomerization. Recombinant bacterially expressed PfP2 protein also undergoes self-association, as shown by SDS-PAGE analysis and light scattering studies. Secondary structure prediction algorithms predict the native PfP2 protein to be largely helical and this is corroborated by circular dichroism investigation. The 1H-15N HSQC spectrum of native P2 showed only 43 cross peaks compared to the expected 138. The observed peaks were found to belong to the C-terminal region, suggesting that this segment is flexible and solvent exposed. In 9 M urea denaturing conditions the chain exhibited mostly non-native β structural propensity. 15N Relaxation data for the denatured state indicated substantial variation in ms-µs time scale motion along the chain. Average area buried upon folding (AABUF) calculations on the monomer enabled identification of hydrophobic patches along the sequence. Interestingly, the segments of slower motion in the denatured state coincided with these hydrophobic patches, suggesting that in the denatured state the monomeric chain undergoes transient hydrophobic collapse. The implications of these results for the folding mechanism and self-association of PfP2 are discussed.
Highlights
The lateral flexible stalk of the large ribosomal subunit, a peculiar region made up of several proteins that is found in almost all ribosomes anchored to a conserved region of the 28S (23S) rRNA is termed the GTPase-associated domain or GTPase center [1]
Plasmodium falciparum P2 (PfP2) is oligomer in solution the ribosomal P2 proteins from eukaryotic organisms are quite conserved, there appear to be distinct differences between protozoan and other P2 proteins (Figure 1A)
In Plasmodium species, SDS-resistant P2 homo-oligomers are detected at certain erythrocytic stages of development, and these appear to be involved in extra-ribosomal functions in the parasites
Summary
The lateral flexible stalk of the large ribosomal subunit, a peculiar region made up of several proteins that is found in almost all ribosomes anchored to a conserved region of the 28S (23S) rRNA is termed the GTPase-associated domain or GTPase center [1]. It has been shown in prokaryotes that L7/L12 is involved in binding translation factors to the ribosome to stimulate GTP hydrolysis through stabilization of the GTPase conformation [8]. Through cryoelectron microscopy these complexes are observed as a lateral protuberance of the large ribosomal subunit and play an important role in translation elongation [9,10]. This assembly is known for large changes of conformation during the different steps of the elongation cycle and has high intrinsic flexibility [11]. The structure of the isolated bacterial L7/L12 complex has been solved by X-ray crystallography and three domains were identified, which include a short alpha-helical N-terminal domain, an intermediary (hinge) domain, and a C-terminal domain found to bind elongation factors [12,13]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
