The amino terminal domain from Mrt4 protein can functionally replace the RNA binding domain of the ribosomal P0 protein

Abstract

In Saccharomyces cerevisiae, the Mrt4 protein is a component of the ribosome assembly machinery that shares notable sequence homology to the P0 ribosomal stalk protein. Here, we show that these proteins can not bind simultaneously to ribosomes and moreover, a chimera containing the first 137 amino acids of Mrt4 and the last 190 amino acids from P0 can partially complement the absence of the ribosomal protein in a conditional P0 null mutant. This chimera is associated with ribosomes isolated from this strain when grown under restrictive conditions, although its binding is weaker than that of P0. These ribosomes contain less P1 and P2 proteins, the other ribosomal stalk components. Similarly, the interaction of the L12 protein, a stalk base component, is affected by the presence of the chimera. These results indicate that Mrt4 and P0 bind to the same site in the 25S rRNA. Indeed, molecular dynamics simulations using modelled Mrt4 and P0 complexes provide further evidence that both proteins bind similarly to rRNA, although their interaction with L12 displays notable differences. Together, these data support the participation of the Mrt4 protein in the assembly of the P0 protein into the ribosome and probably, that also of the L12 protein.

60S ribosome biogenesis requires rotation of the 5S ribonucleoprotein particle

“…2a; Table 1). Mrt4 is homologous to the ribosomal P0 protein and has been suggested to occupy its binding site on the so-called ribosomal stalk base during 60S subunit maturation 28,29 .…”

Yeast Ribosomal Protein L40 Assembles Late into Precursor 60 S Ribosomes and Is Required for Their Cytoplasmic Maturation

“…Preparation of Ribosomes-Ribosomes were enriched as described previously (79). Briefly, 200 ml of cells expressing the HA-tagged or the untagged L40A r-protein were grown in YPD to an A 600 of 0.8, washed, and concentrated in 500 l of ice-cold buffer 1 (10 mM Tris-HCl, pH 7.4; 20 mM KCl; 12.5 mM MgCl 2 ; 5 mM 2-mercaptoethanol) containing a protease inhibitor mixture (Complete EDTA-free, Roche Applied Science).…”

Saccharomyces cerevisiae Ribosomal Protein L26 Is Not Essential for Ribosome Assembly and Function

“…Ribosomes were obtained as previously described (83). Briefly, 200 ml of wild-type or rpl26 null cells was grown in YPD to an OD 600 of 0.8 and concentrated in 500 l of ice-cold buffer 1 (10 mM Tris-HCl, pH 7.4; 20 mM KCl; 12.5 mM MgCl 2 ; 5 mM 2-mercaptoethanol) containing a protease inhibitor cocktail.…”