Cell cycle-specific UNG2 phosphorylations regulate protein turnover, activity and association with RPA.
Human UNG2 is a multifunctional glycosylase that removes uracil near replication forks and in non-replicating DNA, and is important for affinity maturation of antibodies in B cells. How these diverse functions are regulated remains obscure. Here, we report three new phosphoforms of the non-catalytic domain that confer distinct functional properties to UNG2. These are apparently generated by cyclin-dependent kinases through stepwise phosphorylation of S23, T60 and S64 in the cell cycle. Phosphorylation of S23 in late G1/early S confers increased association with replication protein A (RPA) and replicating chromatin and markedly increases the catalytic turnover of UNG2. Conversely, progressive phosphorylation of T60 and S64 throughout S phase mediates reduced binding to RPA and flag UNG2 for breakdown in G2 by forming a cyclin E/c-myc-like phosphodegron. The enhanced catalytic turnover of UNG2 p-S23 likely optimises the protein to excise uracil along with rapidly moving replication forks. Our findings may aid further studies of how UNG2 initiates mutagenic rather than repair processing of activation-induced deaminase-generated uracil at Ig loci in B cells.
Hagen
Lars
L
Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
Kavli
Bodil
B
Sousa
Mirta M L
MM
Torseth
Kathrin
K
Liabakk
Nina B
NB
Sundheim
Ottar
O
Pena-Diaz
Javier
J
Otterlei
Marit
M
Hørning
Ole
O
Jensen
Ole N
ON
Krokan
Hans E
HE
Slupphaug
Geir
G
D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D002417:Cattle; D002453:Cell Cycle / Q000502:physiology*; D045647:DNA Glycosylases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051716:Replication Protein A / Q000378:metabolism* / Q000502:physiology; D012694:Serine / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013912:Threonine / Q000378:metabolism; D014498:Uracil / Q000378:metabolism
D010750:Phosphoproteins; D020033:Protein Isoforms; D051716:Replication Protein A; D013912:Threonine; D012694:Serine; D014498:Uracil; C492570:CCNO protein, human; D045647:DNA Glycosylases