Cell cycle-specific UNG2 phosphorylations regulate protein turnover, activity and association with RPA

TY - JOUR

T1 - Cell cycle-specific UNG2 phosphorylations regulate protein turnover, activity and association with RPA

AU - Hagen, Lars

AU - Kavli, Bodil

AU - Sousa, Mirta M L

AU - Torseth, Kathrin

AU - Liabakk, Nina B

AU - Sundheim, Ottar

AU - Pena Diaz, Javier

AU - Otterlei, Marit

AU - Hørning, Ole

AU - Jensen, Ole N

AU - Krokan, Hans E

AU - Slupphaug, Geir

PY - 2008/1/9

Y1 - 2008/1/9

N2 - 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.

AB - 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.

KW - Amino Acid Sequence

KW - Animals

KW - Catalysis

KW - Cattle

KW - Cell Cycle

KW - DNA Glycosylases

KW - HeLa Cells

KW - Humans

KW - Mice

KW - Molecular Sequence Data

KW - Phosphoproteins

KW - Phosphorylation

KW - Protein Isoforms

KW - Replication Protein A

KW - Serine

KW - Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

KW - Threonine

KW - Uracil

U2 - 10.1038/sj.emboj.7601958

DO - 10.1038/sj.emboj.7601958

M3 - Journal article

C2 - 18079698

SN - 0261-4189

VL - 27

SP - 51

EP - 61

JO - E M B O Journal

JF - E M B O Journal

IS - 1

ER -