Amino acid sequence of the ribosomal protein HS23 from the halophilicHaloarcula marismortui and homology studies to other ribosomal proteins

The ribosomal protein HS23 from the 30S subunit of the extreme halophilicHaloarcula marismortui, belonging to the group of archaea, was isolated either by RP-HLPLC or two-dimensional polyacrylamide gel electrophoresis. The complete amino acid sequence was determined by automated N-terminal microsequencing. The protein consists of 123 residues with a corresponding molecular mass of 12,552 Da as determined by electrospray mass spectroscopy; the pI is 11.04. Homology studies reveal similarities to the eukaryotic ribosomal protein S8 fromHomo sapiens, Rattus norvegicus, Leishmania major, andSaccharomyces cerevisiae.Abbreviations H. marismortui Haloarcula marismortui - PVDF polyvinylidene difluoride - PTH phenylthiohydantoin - RP-HPLC reversed-phase high-performance liquid chromatography - TFA trifluoro acetic acid - TP30 total protein mixture from the 30S ribosomal subunit ofH. marismortui     

Altered ribosomal protein S11 from the SUP46 suppressor of yeast

The dominant suppressor SUP46 of the yeast Saccharomyces cerevisiae was shown to act on a wide range of mutations (preceding paper by Ono et al., 1981). Masurekar et al. (1981) demonstrated that ribosomes from the SUP46 strain make an abnormally high rate of errors in a cell-free translation system. These findings indicated that SUP46 suppression was the result of abnormal ribosomes misreading mutant codons. We have used two-dimensional polyacrylamide gel electrophoresis to show that the S11 protein from the 40 S ribosomal subunit has an altered electrophoretic mobility. Thus the gene product of the SUP46 locus is either the S11 ribosomal protein or an enzyme that modifies the S11 protein. These results demonstrate that the altered S11 protein is responsible for the suppression by misreading.     

Structure and expression of the gene encoding ribosomal protein S1 from the cyanobacterium Synechococcus sp. strain PCC 6301: striking sequence similarity to the chloroplast ribosomal protein CS1

We isolated a 38 kDa ssDNA-binding protein from the unicellular cyanobacterium Synechococcus sp. strain PCC 6301 and determined its N-terminal amino acid sequence. A genomic clone encoding the 38 kDa protein was isolated by using a degenerate oligonucleotide probe based on the amino acid sequence. The nucleotide sequence and predicted amino acid sequence revealed that the 38 kDa protein is 306 amino acids long and homologous to the nuclear-encoded 370 amino acid chloroplast ribosomal protein CS1 of spinach (48% identity), therefore identifying it as ribosomal protein (r-protein) S1. Cyanobacterial and chloroplast S1 proteins differ in size from Escherichia coli r-protein S1 (557 amino acids). This provides an additional evidence that cyanobacteria are closely related to chloroplasts. The Synechococcus gene rps1 encoding S1 is located 1.1 kb downstream from psbB, which encodes the photosystem 11 P680 chlorophyll a apoprotein. An open reading frame encoding a potential protein of 168 amino acids is present between psbB and rps1 and its deduced amino acid sequence is similar to that of E. coli hypothetical 17.2 kDa protein. Northern blot analysis showed that rps1 is transcribed as a monocistronic mRNA.     

Synergistic defect in 60S ribosomal subunit assembly caused by a mutation of Rrs1p, a ribosomal protein L11-binding protein, and 3'-extension of 5S rRNA in Saccharomyces cerevisiae

Rrs1p, a ribosomal protein L11-binding protein, has an essential role in biogenesis of 60S ribosomal subunits. We obtained conditionally synthetic lethal allele with the rrs1-5 mutation and determined that the mutation is in REX1, which encodes an exonuclease. The highly conserved leucine at 305 was substituted with tryptophan in rex1-1. The rex1-1 allele resulted in 3′-extended 5S rRNA. Polysome analysis revealed that rex1-1 and rrs1-5 caused a synergistic defect in the assembly of 60S ribosomal subunits. In vivo and in vitro binding assays indicate that Rrs1p interacts with the ribosomal protein L5–5S rRNA complex. The rrs1-5 mutation weakens the interaction between Rrs1p with both L5 and L11. These data suggest that the assembly of L5–5S rRNA on 60S ribosomal subunits coordinates with assembly of L11 via Rrs1p.     

Ribosomal assembly deficiency in an Escherichia coli thermosensitive mutant having an altered L24 ribosomal protein.

Localized P1 mutagenesis was used to screen for conditionally lethal mutations in ribosomal protein genes. One such mutation, 2859mis, has been mapped inside the ribosomal protein gene cluster at 72 minutes on the Escherichia coli chromosome and cotransduces at 98% with rpsE (S5). The 2869mis mutation leads to thermosensitivity and impaired assembly in vivo of 50 S ribosomal particles at 42 °C. The strain carrying the mutation has an altered L24 ribosomal protein which at 42 °C shows weaker affinity for 23 S RNA than the wild-type protein. The mutational alteration involves a replacement of glycine by aspartic acid in protein L24 from the mutant. We conclude therefore that the 2859mis mutation affects the structural gene for protein L24 (rplX).     

Characterization of the Lactobacillus casei group based on the profiling of ribosomal proteins coded in S10-spc-alpha operons as observed by MALDI-TOF MS

The taxonomy of the members of the Lactobacillus casei group is complicated because of their phylogenetic similarity and controversial nomenclatural status. In this study, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of ribosomal proteins coded in the S10-spc-alpha operon, termed S10-GERMS, was applied in order to classify 33 sample strains belonging to the L. casei group. A total of 14 types of ribosomal protein genes coded in the operon were first sequenced from four type strains of the L. casei group (L. casei JCM 1134^T, L. paracasei subsp. paracasei JCM 8130^T, L. paracasei subsp. tolerans JCM 1171^T, and L. rhamnosus JCM 1136^T) together with L. casei JCM 11302, which is the former type strain of ‘L. zeae’. The theoretical masses of the 14 types of ribosomal proteins used as biomarkers were classified into five types and compiled into a ribosomal protein database. The observed ribosomal proteins of each strain, identified by MALDI-TOF MS, were categorized into types based on their masses, summarized as ribosomal protein profiles, and they were used to construct a phylogenetic tree. The 33 sample strains, together with seven genome-sequenced strains, could be classified into four major clusters, which coincided precisely with the taxa of the (sub)species within the L. casei group. Three “ancient” strains, identified as L. acidophilus and L. casei, were correctly re-identified as L. paracasei subsp. paracasei by S10-GERMS. S10-GERMS would thus appear to be a powerful tool for phylogenetic characterization, with considerable potential for management of culture collections.     

The complete amino acid sequence of ribosomal protein S12 from Bacillus stearothermophilus

The amino acid sequence of ribosomal protein S12 from Bacillus stearothermophilus has been completely determined. The sequence data were mainly obtained by manual sequencing of peptides derived from digestion with trypsin, Staphylococcus aureas protease and pepsin. A few overlaps of tryptic peptides were established by DNA sequence analysis of a chromosomal fragment containing the rpsL gene coding for ribosomal protein S12. The protein contains 138 amino acid residues and has an M_r of 15208. Comparison of this sequence with the sequences of the ribosomal S12 proteins from E. coli as well as from Euglena, tobacco and liverwort chloroplasts shows that 75% of the amino acid residues are identical within the S12 proteins of all four species. Therefore, S12 is the most strongly conserved ribosomal protein known so far.     

Methylation of ribosomal proteins in HeLa cells.

Methylated amino acids from both 40 and 60S subunit proteins of HeLa cytoplasmic ribosome were analyzed. It was observed that methylation of ribosomal proteins occurs in both subunits with N^G,N^G-dimethylarginine as the major methylated amino acid. The presence of N^G,N^G-dimethylarginine has been identified by high-voltage paper electrophoresis, by paper chromatography, and by amino acid analysis. In addition, both ribosomal subunits contain methylated lysines with ?-N-trimethyllysine being the predominant one, followed by ?-N-dimethyllysine. Little, if any ?-N-monomethyllysine was detected in either subunit. The cytoplasmic 60S ribosomal subunit contains much more ?-N-trimethyllysine compared to the 40S ribosomal subunit. The possible biological significance of methylation was discussed.     

The complete primary structure of ribosomal protein L1 fromThermus thermophilus

The primary structure of the 23S rRNA binding ribosomal protein L1 from the 50S ribosomal subunit ofThermus thermophilus ribosomes has been elucidated by direct protein sequencing of selected peptides prepared by enzymatic and chemical cleavage of the intact purified protein. The polypeptide chain contains 228 amino acids and has a calculated molecular mass of 24,694 D. A comparison with the primary structures of the corresponding proteins fromEscherichia coli andBacillus stearothermophilus reveals a sequence homology of 49% and 58%, respectively. With respect to both proteins, L1 fromT. thermophilus contains particularly less Ala, Lys, Gln, and Val, whereas its content of Glu, Gly, His, Ile, and Arg is higher. In addition, two fragments obtained by limited proteolysis of the intact, unmodified protein were characterized.     

A missense mutation in the gene coding for ribosomal protein S17 (rpsQ) leading to ribosomal assembly defectivity in Escherichia coli.

Summary The conditionally lethal mutation, 286lmis, has been mapped inside the ribosomal protein gene cluster at 72 minutes on the Escherichia coli chromosome and was found to cotransduce at 97% with rpsE (S5). The 2861mis mutation leads to thermosensitivity and impaired assembly in vivo of 30S ribosomal particles at 42°C. The strain carrying the mutation has an altered S17 ribosomal protein; the mutational alteration involves a replacement of serine by phenylalanine in protein S17. Spontaneous reversion to temperature independence can restore the normal assembly in vivo of 30S ribosomal subunits at 42°C and the normal chromatographical sehaviour of the S17 ribosomal protein in vitro. We conclude therefore that the 2861mis mutation affects the structural gene for protein S17 (rpsQ).     

Sequencing and analysis of the Thermus thermophilus ribosomal protein gene cluster equivalent to the spectinomycin operon

To assess the organization of the Thermus thermophilus ribosomal protein genes, a fragment of DNA containing the complete S10 region and ten ribosomal protein genes of the spc region was cloned, using an oligonucleotide coding for the N-terminal amino acid (aa) sequence of T. thermophilus S8 protein as hybridization probe. The nucleotide sequence of a 4290 bp region between the rps17 and rpl15 genes was determined. Comparative analysis of this gene cluster showed that the gene arrangement (S17, L14, L24, L5, S14, S8, L6, L18, S5, L30 and L15) is identical to that of eubacteria. However, T. thermophilus ribosomal protein genes corresponding to the Escherichia coli S10 and spc operons are not resolved into two clusters: the stop codon of the rps17 gene (the last gene of the S10 operon in E. coli) and the start codon of the rpl14 gene (the first gene of the spc operon in E. coli) overlap. Most genes, except the rps14-rps8 intergenic spacer (69 bp), are separated by very short (only 3–7 bp) spacer regions or partially overlapped. The deduced aa sequences of T. thermophilus proteins share about 51–100% identities with the sequences of homologous proteins from thermophile Thermus aquaticus and Thermotoga maritima and 27–70% identities with the sequences of their mesophile counterparts.     

An intron in a ribosomal protein gene from Tetrahymena

We have cloned and sequenced a single copy gene encoding a ribosomal protein from the ciliate Tetrahymena thermophila. The gene product was identified as ribosomal protein S25 by comparison of the migration in two-dimensional polyacrylamide gels of the protein synthesized by translation in vitro of hybrid-selected mRNA and authentic ribosomal proteins. The proteins show strong homology to ribosomal protein S12 from Escherichia coli. The coding region of the gene is interrupted by a 979-bp intron 68 bp downstream of the translation start. This is the first intron in a protein encoding gene of a ciliate to be described at the nucleotide sequence level. The intron obeys the GT/AG rule for splice junctions of nuclear mRNA introns from higher eukaryotes but lacks the pyrimidine stretch usually found in the immediate vicinity of the 3' splice junction. The structure of the intron and the fact that it is found together with the well described self-splicing rRNA intron is discussed in relation to the evolution of RNA splicing.     

PRMT3 is a ribosomal protein methyltransferase that affects the cellular levels of ribosomal subunits

The mammalian protein arginine methyltransferase 3 (PRMT3) catalyzes the formation of asymmetric (type I) dimethylarginine in vitro. As yet, natural substrates and cellular pathways modulated by PRMT3 remain unknown. Here, we have identified an ortholog of PRMT3 in fission yeast. Tandem affinity purification of fission yeast PRMT3 coupled with mass spectrometric protein identification revealed that PRMT3 associates with components of the translational machinery. We identified the 40S ribosomal protein S2 as the first physiological substrate of PRMT3. In addition, a fraction of yeast and human PRMT3 cosedimented with free 40S ribosomal subunits, as determined by sucrose gradient velocity centrifugation. The activity of PRMT3 is not essential since prmt3-disrupted cells are viable. Interestingly, cells lacking PRMT3 showed an accumulation of free 60S ribosomal subunits resulting in an imbalance in the 40S:60S free subunits ratio; yet pre-rRNA processing appeared to occur normally. Our results identify PRMT3 as the first type I ribosomal protein arginine methyltransferase and suggest that it regulates ribosome biosynthesis at a stage beyond pre-rRNA processing.     

Characterisation ofSaccharomyces cerevisiae genes encoding ribosomal protein YL6

We have characterised aSaccharomyces cerevisiae cDNA (cDNA13), originally isolated on the basis of the short half-life of the corresponding mRNA. We show here that its sequence is closely related to that of the genes encoding ribosomal proteins K37, KD4 and K5 ofSchizosaccharomyces pombe. ‘mRNA13’ also behaves like other mRNAs encoding ribosomal proteins, in that its abundance increases sharply when glucose is added to cells grown on ethanol (nutrient-up shift), and declines when cells are subjected to a mild heat-shock. Unspliced mRNA13 accumulates when cells bearing a temperature-sensitive splicing mutation are grown at the restrictive temperature. The gene(s) corresponding to cDNA13, like other ribosomal protein genes ofS. cerevisiae, thus contain an intron. Southern blot analysis indicates the presence of two separate loci related to cDNA13 in theS. cerevisiae genome. From the sequence of one of these, a complete polypeptide sequence was deduced. The first 40 amino acids are identical to those of YL6, aS. cerevisiae ribosomal protein characterised only by N-terminal protein sequence analysis. There is clear evidence within the genomic sequence for the predicted intron, and for elements similar to those that regulate expression of otherS. cerevisiae ribosomal protein genes.     

Arabidopsis L10 ribosomal proteins in UV-B responses

Ribosomal protein L10 (RPL10) is a ubiquitous protein that participates in joining the 40S and 60S ribosomal subunits into a functional 80S ribosome; however, increasing evidence indicates that RPL10 from various organisms has multiple extra-ribosomal functions, besides being a constituent of ribosome and its role in translation. Arabidopsis thaliana contains in its genome three genes encoding RPL10, named RPL10A, RPL10B and RPL10C. Previously, we found that in maize and in A. thaliana, UV-B induces a reduction in protein biosynthesis, probably as a consequence of ribosomal damage; however, cellular recovery occurs in the absence of UV-B. Here, we show that RPL10s are differentially regulated by UV-B in a dosage and time dependent manner: RPL10C is induced, RPL10B is downregulated at high UV-B intensity and RPL10A is not UV-B regulated. In addition, by co-immunoprecipitation studies using RPL10 antibodies and proteins from control and UV-B irradiated Arabidopsis plants, we demonstrate that RPL10 associates with different proteins under the two different conditions, including nuclear proteins, suggesting that at least one isoform may have extra-ribosomal roles.Key words: UV-B exposure, translation, ribosomal protein, co-immunoprecipitation     

Identification of ribosomal protein family in triple-negative breast cancer by bioinformatics analysis

Triple-negative breast cancer (TNBC) accounts for ∼20% of all breast cancer (BC) cases. The management of TNBC represents a challenge due to its worse prognosis, heterogeneity and lack of targeted therapy. Moreover, its mechanisms are not fully clear. The aim of the study is to identify crucial genes between TNBC and non-TNBC for underlying targets for diagnostic and therapeutic methods of TNBC. The differentially expressed genes (DEGs) between TNBC and non-TNBC were selected from the Gene Expression Omnibus (GEO) database after the integrated analysis of two datasets ({"type":"entrez-geo","attrs":{"text":"GSE65194","term_id":"65194"}}GSE65194 and {"type":"entrez-geo","attrs":{"text":"GSE76124","term_id":"76124"}}GSE76124). Then Gene ontology (GO) and KEGG analysis were performed by DAVID database, protein–protein interaction (PPI) of DEGs was constructed by Search Tool for the Retrieval of Reciprocity Genes (STRING) database. Furthermore, centrality analysis and module analysis were carried out by Cytoscape to analyze the TNBC-related PPI. Subsequently, overall survival (OS) analysis was performed by GEPIA. Finally, the expressions of these key genes in TNBC and non-TNBC tissues were tested by qRT-PCR. The results showed that 955 DEGs were obtained, which were mainly enriched in ribosome, ribosomal subunit, and so on. Moreover, 19 candidate genes were focused on by centrality analysis and module analysis. Furthermore, we found the low expressions of ribosomal protein S9 (RPS9), ribosomal protein S14 (RPS14), ribosomal protein S27 (RPS27), ribosomal protein L11 (RPL11) and ribosomal protein L14 (RPL14) were related to a poor OS in BC patients. Additionally, qRT-PCR results suggested that these five genes were notably down-regulated in TNBC tissues. In summary, the present study suggests that ribosomal proteins are related to TNBC, and they may play an important role in the diagnosis, treatment and prognosis of TNBC.     

Nuclear genome codes for chloroplast ribosomal proteins in Acetabularia. II. Nuclear transplantation experiments

The protein patterns of chloroplast ribosomes of Acetabularia have been established by means of polyacrylamide gel electrophoresis. The protein patterns of the faster sedimenting 44S ribosomal subunit of A. mediterranea, A. cliftonii, and A. crenulata have been compared and species specific differences are described. The protein patterns of hybrid cells consisting of a host cytoplasm from one species and a nucleus from another species is changed to that of the nucleus donor species after some weeks. The results indicate that at least part of the chloroplast ribosomal proteins are coded by the nuclear genome.     

Position of protein S1 in the 30 S ribosomal subunit of Escherichia coli

The results of neutron distance measurement involving ribosomal protein S1 from Escherichia coli are reported. These data provide a position for S1 on the small ribosomal subunit. They also indicate that S1, bound to the ribosome, has a radius of gyration of 60 to 65 Å, suggesting that its axial ratio in the bound state is similar to that it has as a free molecule in solution; namely, 10: 1. The implications of these results for our understanding of the mode of action of S1 are discussed.     

Late steps in the assembly of 30 S ribosomal proteins in vivo in a spectinomycin-resistant mutant of Escherichia coli.

The late steps in ribosome assembly in vivo were studied by characterizing mutations which suppress the cold-sensitivity of a spectinomycin-resistant mutant of Escherichia coli. The results obtained indicated that the cold-sensitivity could be relieved by secondary alterations in either the S2, S3 or S5 protein of the 30 S ribosomal subunit. The gene controlling the alteration of S2 protein was closely linked to the polC gene located at about 3.5 minutes on the genetic map of E. coli, whereas S3 and S5 suppressor genes were linked to the str-spc region at 64 minutes. A possible model in which the S2, S3 and S5 proteins constitute a sub-assembly pathway in the assembly of 30 S subunits in vivo is discussed.     

Individual ribosomal protein pool size and turnover rate in Escherichia coli

The pool size of free individual ribosomal proteins present in the cell sap of Escherichia coli has been determined by pulse-labelling a culture before a chase with cold marker.Ribosomes plus ribosomal precursor particles were prepared together and the proteins from this fraction purified. The specific radioactivity of each 30 S and 50 S protein was measured at the time of pulse and at the various times of chase: unequal labelling was already observed at the time of pulse; the kinetics of chase of most 30 S proteins reached a plateau very rapidly; the kinetics of 50 S proteins were more variable. Precise calculation of individual pool size was carried out using the mathematical model described in the Appendix. Almost all ribosomal 30 S proteins have a pool size close to zero. Only four 30 S proteins (S10, S16, S17 and S18) have a sizeable pool (2 to 6% of the corresponding ribosomal protein). Most 50 S proteins have a small pool size (1 to 2%). The free ribosomal proteins of the pool are transferred to mature ribosomes; the half-life of these proteins in the pool has been calculated (0 to 1·4 min). Finally, as judged from the kinetic data, no degradation of ribosome-bound protein was apparent. The significance of the results is discussed with respect to the function of ribosome and the process of ribosome biogenesis.