Ribosomal Protein S3 Negatively Regulates Unwinding Activity of RecQ-like Helicase 4 through Their Physical Interaction.
Human RecQ-like helicase 4 (RECQL4) plays crucial roles in replication initiation and DNA repair; however, the contextual regulation of its unwinding activity is not fully described. Mutations in RECQL4 have been linked to three diseases including Rothmund-Thomson syndrome, which is characterized by osteoskeletal deformities, photosensitivity, and increased osteosarcoma susceptibility. Understanding regulation of RECQL4 helicase activity by interaction partners will allow deciphering its role as an enzyme and a signaling cofactor in different cellular contexts. We became interested in studying the interaction of RECQL4 with ribosomal protein S3 (RPS3) because previous studies have shown that RPS3 activity is sometimes associated with phenotypes mimicking those of mutated RECQL4. RPS3 is a small ribosomal protein that also has extraribosomal functions, including apurnic-apyrimidinic endonuclease-like activity suggested to be important during DNA repair. Here, we report a functional and physical interaction between RPS3 and RECQL4 and show that this interaction may be enhanced during cellular stress. We show that RPS3 inhibits ATPase, DNA binding, and helicase activities of RECQL4 through their direct interaction. Further domain analysis shows that N-terminal 1-320 amino acids of RECQL4 directly interact with the C-terminal 94-244 amino acids of RPS3 (C-RPS3). Biochemical analysis of C-RPS3 revealed that it comprises a standalone apurnic-apyrimidinic endonuclease-like domain. We used U2OS cells to show that oxidative stress and UV exposure could enhance the interaction between nuclear RPS3 and RECQL4. Regulation of RECQL4 biochemical activities by RPS3 along with nuclear interaction during UV and oxidative stress may serve to modulate active DNA repair.
From the Molecular and Cell Biology, Taiwan International Graduate Program and ajaypatil@gate.sinica.edu.tw ajayvets@gmail.com.|the Graduate Institute of Life Science, National Defense Medical Center, Taipei 114, Taiwan, and.|the Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei 115, Taiwan.
Ajay Vitthal
AV
Patil
From the Molecular and Cell Biology, Taiwan International Graduate Program and.|the Graduate Institute of Life Science, National Defense Medical Center, Taipei 114, Taiwan, and.|the Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei 115, Taiwan.|the Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
Tao-Shih
TS
Hsieh
D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D053484:RecQ Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
C578290:RPS3 protein, human; D012269:Ribosomal Proteins; C506731:RECQL4 protein, human; D053484:RecQ Helicases
DNA helicase; DNA repair; base excision repair (BER); genomic instability; oxidative stress; protein-protein interaction