The ribosomal P-proteins of the medfly Ceratitis capitata form a heterogeneous stalk structure interacting with the endogenous P-proteins, in conditional P0-null strains of the yeast Saccharomyces cerevisiae

Abstract

The genes encoding the ribosomal P-proteins CcP0, CcP1 and CcP2 of Ceratitis capitata were expressed in the conditional P0-null strains W303dGP0 and D67dGP0 of Saccharomyces cerevisiae, the ribosomes of which contain either standard amounts or are totally deprived of the P1/P2 proteins, respectively. The presence of the CcP0 protein restored cell viability but reduced the growth rate. In the W303CcP0 strain, all four acidic yeast proteins were found on the ribosomes, but in notably less quantity, while a preferable binding of the YP1alpha/YP2betapair was established. In the absence of the endogenous P1/P2 proteins in the D67CcP0 strain, the complementation capacity of the CcP0 protein was considerably reduced. The simultaneous expression of the three medfly genes resulted in alterations of the stalk composition: both the CcP1 and CcP2 proteins were found on the particles substituting the YP1alphaand YP2alpha proteins, respectively, but their presence did not alter the growth rate, except in the case of the YP1alpha/betadefective strain, where a helping effect on the binding of the YP2alphaand YP2betaproteins on the ribo-somes was confirmed. Therefore, the medfly ribosomal P-proteins complement the yeast P-protein deficient strains forming an heterogeneous ribosomal stalk, which, however, is not functionally equivalent to the endogenous one.

Ribosomal P0 Protein Domain Involved in Selectivity of Antifungal Sordarin Derivatives

“…In the ribosome, mainly proteins P1␣ and P2␤ are present and bind the heterologous HsP0 with higher affinity than P1␤ and P2␣, suggesting that they are functionally closer to the human P1 and P2. Confirming previous reports (7,15), the results indicate that evolution has affected less the interaction of P0 with rRNA than with the other stalk proteins. The decrease in the 12-kDa protein content of the ribosome may be, at least in part, responsible for the reduction in the transformed strain growth rate.…”

In vivo analysis of the acidic ribosomal proteins BmP1 and BmP2 of the silkworm Bombyx mori in the yeast Saccharomyces cerevisiae

“…However, it seems that in contrast to the control B. mori ribosomes, the most basic, non-phosphorylated form of BmP1 is mainly detected in D67BmP1. P1 protein from the medfly C. capitata has been previously shown to have a similar behavior when expressed in yeast (Gagou et al, 2000). These results might indicate that the yeast phosphorylation system does not recognize the heterologous proteins.…”

“…Thus, studies on the expression of proteins from other eukaryotes in S. cerevisiae have shown the incorporation of the heterologous proteins to the ribosomal particles and their capacity to complement at different extent the absence of the endogenous proteins. This incorporation resulted in a reduced growth rate, in the case of proteins from the medfly Ceratitis capitata (Gagou et al, 2000), and Aspergillus fumingatus (Santos and Ballesta, 2002). Similarly, in the case of the silkworm Bombyx mori, BmP0 protein, when expressed in the conditional P0-null mutant S. cerevisiae D67dGP0, was able to bind to the ribosome in the absence of the yeast acidic proteins YP1/YP2, resulting in a reduced growth rate of the transformed strain (Kouyanou et al, 2003).…”

Functional complementation of yeast ribosomal P0 protein with Plasmodium falciparum P0

“…Like the PfP0 gene, the P0 genes from the insects Ceratitis capitata and Bombyx mori have been reported to complement D67dGP0 strain. However, the putative leucine zipper is present in all the insect P0 proteins, and insect P0 proteins do bind to the acidic proteins (Gagou et al, 2000;Kouyanou et al, 2003). The genome database for P. falciparum predicts putative single genes for orthologous PfP1 and PfP2 acidic proteins.…”

“…Therefore, in addition to the structural contribution to the stalk region of the 60S ribosomal subunit, the acidic proteins are hypothesized to play a role in the translation regulatory mechanism in yeast (Remacha et al, 1995). Amongst all the orthologous P0 genes used for the complementation analysis, only the insect P0 proteins could complement the strain D67dGP0 (Gagou et al, 2000). Based on these results, it has been postulated that the amino terminal rRNA binding domain of most of the eukaryotic P0 proteins is conserved, while the carboxy-terminal located acid protein binding domain has diverged considerably.…”