Human SHPRH is a ubiquitin ligase for Mms2–Ubc13-dependent polyubiquitylation of proliferating cell nuclear antigen

doi:10.1073/pnas.0608595103

Human SHPRH is a ubiquitin ligase for Mms2–Ubc13-dependent polyubiquitylation of proliferating cell nuclear antigen

*Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary;
^†Molecular Biology Program, Memorial Sloan–Kettering Cancer Center, New York, NY 10021; and
^§Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555

Contributed by Jerard Hurwitz, October 3, 2006 (received for review September 26, 2006)

Abstract

Human SHPRH gene is located at the 6q24 chromosomal region, and loss of heterozygosity in this region is seen in a wide variety of cancers. SHPRH is a member of the SWI/SNF family of ATPases/helicases, and it possesses a C₃HC₄ RING motif characteristic of ubiquitin ligase proteins. In both of these features, SHPRH resembles the yeast Rad5 protein, which, together with Mms2–Ubc13, promotes replication through DNA lesions via an error-free postreplicational repair pathway. Genetic evidence in yeast has indicated a role for Rad5 as a ubiquitin ligase in mediating the Mms2–Ubc13-dependent polyubiquitylation of proliferating cell nuclear antigen. Here we show that SHPRH is a functional homolog of Rad5. Similar to Rad5, SHPRH physically interacts with the Rad6–Rad18 and Mms2–Ubc13 complexes, and we show that SHPRH protein is a ubiquitin ligase indispensable for Mms2–Ubc13-dependent polyubiquitylation of proliferating cell nuclear antigen. Based on these observations, we predict a role for SHPRH in promoting error-free replication through DNA lesions. Such a role for SHPRH is consistent with the observation that this gene is mutated in a number of cancer cell lines, including those from melanomas and ovarian cancers, which raises the strong possibility that SHPRH function is an important deterrent to mutagenesis and carcinogenesis in humans.

Footnotes

^‡To whom correspondence should be addressed. E-mail: j-hurwitz{at}ski.mskcc.org
Author contributions: S.P. and L.H. designed research; I.U., I.H., K.F., B.S., A.B., L.P., S.P., and L.H. performed research; V.B., J.H., and L.P. contributed new reagents/analytic tools; L.H. analyzed data; and S.P. and L.H. wrote the paper.
The authors declare no conflict of interest.
Abbreviations:

PCNA,

proliferating cell nuclear antigen;

PRR,

postreplicational repair;

TLS,

translesion synthesis;

Pol,

DNA polymerase.