Structural basis of ubiquitin recognition by translesion synthesis DNA polymerase ι.
Cells have evolved mutagenic bypass mechanisms that prevent stalling of the replication machinery at DNA lesions. This process, translesion DNA synthesis (TLS), involves switching from high-fidelity DNA polymerases to specialized DNA polymerases that replicate through a variety of DNA lesions. In eukaryotes, polymerase switching during TLS is regulated by the DNA damage-triggered monoubiquitylation of PCNA. How the switch operates is unknown, but all TLS polymerases of the so-called Y-family possess PCNA and ubiquitin-binding domains that are important for their function. To gain insight into the structural mechanisms underlying the regulation of TLS by ubiquitylation, we have probed the interaction of ubiquitin with a conserved ubiquitin-binding motif (UBM2) of Y-family polymerase Polι. Using NMR spectroscopy, we have determined the structure of a complex of human Polι UBM2 and ubiquitin, revealing a novel ubiquitin recognition fold consisting of two α-helices separated by a central trans-proline residue conserved in all UBMs. We show that, different from the majority of ubiquitin complexes characterized to date, ubiquitin residue Ile44 only plays a modest role in the association of ubiquitin with Polι UBM2. Instead, binding of UBM2 is centered on the recognition of Leu8 in ubiquitin, which is essential for the interaction.
Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, United States.
Gaofeng
G
Cui
Robert C
RC
Benirschke
Han-Fang
HF
Tuan
Nenad
N
Juranić
Slobodan
S
Macura
Maria Victoria
MV
Botuyan
Georges
G
Mer
D000595:Amino Acid Sequence; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D009687:Nuclear Proteins / Q000378:metabolism*; D009713:Nucleotidyltransferases / Q000378:metabolism*; D013329:Structure-Activity Relationship; D025801:Ubiquitin / Q000378:metabolism*; D054875:Ubiquitination; D000094769:DNA Polymerase iota; D000099270:Y-Family DNA Polymerases
D004259:DNA-Directed DNA Polymerase; D009687:Nuclear Proteins; D009713:Nucleotidyltransferases; D025801:Ubiquitin; D000094769:DNA Polymerase iota; C429004:REV1 protein, human; D000099270:Y-Family DNA Polymerases; C000722070:POLI protein, human