Disease relevance of RpS3

• Furthermore, the Drosophila S3 cDNA was shown to protect AP endonuclease deficient E. coli cells against H(2)O(2) and MMC, and also protect 8-oxoG repair deficient mutM E. coli strains against MMC and H2O2 cell toxicity [1].
• The Drosophila S3 multifunctional DNA repair/ribosomal protein protects Fanconi anemia cells against oxidative DNA damaging agents [1].
• In the stronger allele (110 bp insert) RPS3 mRNA levels are reduced by approximately 60%, resulting in an extreme Minute phenotype that includes many morphological abnormalities as well as sterility in both males and females due to disruption of early gametogenesis [2].

High impact information on RpS3

• Here, Drosophila ribosomal protein S3 is shown to cleave DNA containing 8-oxoguanine residues efficiently, The ribosomal protein also contains an associated apurinic/apyrimidinic (AP) lyase activity, cleaving phosphodiester bonds via a beta,delta elimination reaction [3].
• The Drosophila S3 ribosomal protein has important roles in both protein translation and DNA repair [4].
• In support of this were experiments executed in vivo that showed that human S3 and the Drosophila site-directed glutamine-changed S3 performed poorly when compared with Drosophila wild-type S3 and its ability to protect a bacterial mutant from the harmful effects of DNA-damaging agents [4].
• Of the 15 additional modified bases present in the DNA substrate, the only other one acted on by S3 protein was 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) [5].
• The Drosophila gene was in turn used to construct fusions between S3 and glutathione S-transferase that were overexpressed in Escherichia coli, purified on affinity columns, and subsequently used for antibody production and biochemical analysis [6].

Biological context of RpS3

• These comparisons revealed that RpS3 genes from plants to mammals have highly conserved coding and amino acid sequences, and also protein size [7].
• Whereas invertebrate RpS3 genes are small in size and gene organization is variable (from zero to four introns), vertebrates have a considerably larger (but variable) gene size and a uniform gene organization [7].
• Cloning of the Drosophila ribosomal protein S3: another multifunctional ribosomal protein with AP endonuclease DNA repair activity [8].
• Nucleotide sequence analysis revealed a 70-75% identity to the human and rat ribosomal protein S3 genes, and to the Xenopus ribosomal protein S1a gene [9].
• Another notable finding was that ectopic expression of either dOgg1 or RpS3 in mitochondria increased cell survival after exposure to the nitric oxide donor SNAP [10].

Anatomical context of RpS3

• The high conservation through different phyla may suggest that RPS3 might be under great functional constraints, both in its capacity as a component of the ribosome and as a component of a DNA repair system [7].
• Effects of ectopic expression of Drosophila DNA glycosylases dOgg1 and RpS3 in mitochondria [10].
• To establish a basis for participation of RpS3 in DNA repair in mosquitoes, we cloned RpS3 cDNAs from Aedes aegypti and Aedes albopictus mosquito cell lines [11].
• As expected, the S3 antigen was found associated with purified preparations of ribosomes, but notably the protein was also observed in the nucleus where it was found to be tightly associated with the nuclear matrix [6].
• The data confirm and extend our previous results obtained with Chinese hamster CHO cells and indicate that elevated expression of dS3 may be toxic to at least some types of mammalian cells, thus limiting its use in vivo as a protective factor against oxidative DNA damage [12].

Associations of RpS3 with chemical compounds

• None of the insect RpS3 proteins available in the database, other than those from Drosophila, contain glutamine at position 59 [11].
• Although RpS3 proteins are well-conserved among eukaryotes, a critical glutamine residue, Q59, essential to robust DNA repair activity in the Drosophila protein, is replaced by an asparagine (N) in all three mosquito RpS3 proteins [11].
• Both Fpg and S3 also contain a deoxyribophosphodiesterase (dRpase) activity that removes 2-deoxyribose-5-phosphate at an incised 5' apurinic/apyrimidinic (AP) sites via a beta-elimination reaction [13].
• In Drosophila, the S3 ribosomal protein has been shown to act as a DNA glycosylase/AP lyase capable of releasing 8-hydroxyguanine (8-OH-Gua) in damaged DNA [14].

Other interactions of RpS3

• Biochemical tests were originally performed to see if overexpressed PO contained DNase activity similar to that recently reported for the apurinic/apyrimidinic (AP) lyase activity associated with Drosophila ribosomal protein S3 [15].
• That heteroalleles in M(3)95A can mimic the phenotypic variations that exist between different Minute/rp-gene mutations strongly suggests that all phenotypes primarily are caused by reductions in maximum protein synthesis rates, but that the sensitivity for reduced levels of the individual rp-gene products is different [2].

Analytical, diagnostic and therapeutic context of RpS3

• Even in the absence of oxidative challenge, cells expressing RpS3 or dOgg1 in mitochondria exhibited increased apoptosis relative to controls, as determined by flow-cytometric analysis of Annexin V and DNA degradation measured by the Comet assay [10].
• Here we show, using DNA substrates prepared by gamma-irradiation under N2O and analyzed by gas chromatography/isotope-dilution mass spectrometry, that S3 protein efficiently liberates 8-oxoGua as a free base from the damaged DNA substrate [5].
• Antibody specific for S3 was originally tested to determine the subcellular location of S3 by Western (immunoblot) analysis [6].
• Limiting dilution and Fluorescence-Activated Cell Sorting (FACS) were used in an effort to isolate cells with elevated EGFP-dS3 expression; however, the cells that were isolated invariably had severe growth impairment [12].

References