title: Human ribosomal protein S3 (hRpS3) interacts with uracil-DNA glycosylase (hUNG) and stimulates its glycosylase activity.
abstract: Human ribosomal protein S3 (hRpS3) is a small ribosomal subunit showing apurinic/apyrimidinic (AP) lyase activity and has been suggested to play a role in the cellular DNA-damage response pathway. However, the functional interactions between hRpS3 and other base excision repair (BER) DNA glycosylases have not been reported. We identified, for the first time, the interaction between hRpS3 and human uracil-DNA glycosylase (hUNG) and investigated the functional consequences of this interaction. hRpS3 was shown to interact with hUNG in co-immunoprecipitation assay using transiently transfected HEK293 cells and GST pull-down assay using microbial expression systems. In an assay using a 5'-end-radiolabeled 39-mer oligonucleotide duplex containing a U/G mismatch, hRpS3 dramatically stimulated the uracil-excision activity of hUNG, whereas hRpS3 alone had no cleavage activity. Pre-incubation of hRpS3 with the U/G mismatch containing DNA duplex also increased the hUNG uracil-excision activity; however, hRpS3 did not increase the DNA binding activity of hUNG in a trapping assay of hUNG and the U/G mismatch containing DNA duplex using UV cross-linking. hRpS3 has been suggested to stimulate the uracil-excision activity of hUNG by enhancing its dissociation from AP sites and increasing its turn-over rate. The disruption of hRpS3 by small-interfering RNA (siRNA-hRpS3) transfection reduced the uracil-excision activity preserved in cell extracts, whereas the supplement of purified hRpS3 retained uracil-excision activity. These results strongly suggest that hRpS3 may be involved in the uracil-excision pathway, probably by participating in the DNA repair mechanism to remove uracil generated by the deamination of cytosine in DNA, and by preventing C/G-->T/A transition mutations.
authors.affiliation: Department of Advanced Technology Fusion, Konkuk University, Seoul, Republic of Korea.
authors.forename: Sung Il
authors.initials: SI
authors.lastname: Ko
authors.forename: Jong-Hwa
authors.initials: JH
authors.lastname: Park
authors.forename: Min Ju
authors.initials: MJ
authors.lastname: Park
authors.forename: Joon
authors.initials: J
authors.lastname: Kim
authors.forename: Lin-Woo
authors.initials: LW
authors.lastname: Kang
authors.forename: Ye Sun
authors.initials: YS
authors.lastname: Han
mesh_terms: D020137:Base Pair Mismatch / Q000502:physiology; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004260:DNA Repair / Q000502:physiology; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism; D004789:Enzyme Activation; D055785:Gene Knockdown Techniques; D006801:Humans; D017354:Point Mutation / Q000502:physiology; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism* / Q000502:physiology*; D014162:Transfection; D014498:Uracil / Q000378:metabolism; D051981:Uracil-DNA Glycosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D012269:Ribosomal Proteins; C044152:ribosomal protein S3; D014498:Uracil; D004247:DNA; D051981:Uracil-DNA Glycosidase; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase