Spartan/C1orf124 is important to prevent UV-induced mutagenesis.
Uninterrupted replication across damaged DNA is critical to prevent replication fork collapse and resulting double-strand DNA breaks. Rad18-mediated PCNA ubiquitination is a crucial event that triggers a number of downstream pathways important for lesion bypass. Here, we report characterization of Spartan, an evolutionarily conserved protein containing a PCNA-interacting peptide motif, called a PIP box, and a UBZ4 ubiquitin-binding domain. Spartan is a nuclear protein and forms DNA damage-induced foci that colocalize with markers for stalled DNA replication. Focus formation of Spartan requires its PIP-box and the UBZ4 domain and is dependent on Rad18 and the PCNA ubiquitination site, indicating that Spartan is recruited to ubiquitinated PCNA. Spartan depletion results in increased mutagenesis during replication of UV-damaged DNA. Taken together, our data suggest that Spartan is recruited to sites of stalled replication via ubiquitinated PCNA and plays an important role to prevent mutations associated with replication of damaged DNA.
Division of Oncology Research, Mayo College of Medicine, Mayo Clinic, Rochester, MN, USA.
Yuka
Y
Machida
Myoung Shin
MS
Kim
Yuichi J
YJ
Machida
D000595:Amino Acid Sequence; D017124:Conserved Sequence; D004249:DNA Damage; D004261:DNA Replication / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D019143:Evolution, Molecular; D049452:Green Fluorescent Proteins / Q000378:metabolism; D045325:HCT116 Cells; D006801:Humans; D008239:Lysine / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000528:radiation effects*; D009154:Mutation / Q000235:genetics; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000528:radiation effects; D013312:Stress, Physiological / Q000528:radiation effects; D013329:Structure-Activity Relationship; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D014466:Ultraviolet Rays
D004268:DNA-Binding Proteins; D018809:Proliferating Cell Nuclear Antigen; C485954:RAD18 protein, human; C574636:SPRTN protein, human; D025801:Ubiquitin; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D044767:Ubiquitin-Protein Ligases; D008239:Lysine