Human HLTF functions as a ubiquitin ligase for proliferating cell nuclear antigen polyubiquitination

doi:10.1073/pnas.0800563105

Human HLTF functions as a ubiquitin ligase for proliferating cell nuclear antigen polyubiquitination

*Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Temesvari Körút 62, H-6726, Szeged, Hungary;
^†Department of Molecular Biology and Virology, Memorial Sloan–Kettering Cancer Center, 1275 York Avenue, New York, NY 10021-6007; and
^§Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-1061

Contributed by Jerard Hurwitz, January 18, 2008 (received for review January 11, 2008)

Abstract

Human helicase-like transcription factor (HLTF) is frequently inactivated in colorectal and gastric cancers. Here, we show that HLTF is a functional homologue of yeast Rad5 that promotes error-free replication through DNA lesions. HLTF and Rad5 share the same unique structural features, including a RING domain embedded within a SWI/SNF helicase domain and an HIRAN domain. We find that inactivation of HLTF renders human cells sensitive to UV and other DNA-damaging agents and that HLTF complements the UV sensitivity of a rad5Δ yeast strain. Also, similar to Rad5, HLTF physically interacts with the Rad6–Rad18 and Mms2–Ubc13 ubiquitin-conjugating enzyme complexes and promotes the Lys-63-linked polyubiquitination of proliferating cell nuclear antigen at its Lys-164 residue. A requirement of HLTF for error-free postreplication repair of damaged DNA is in keeping with its cancer-suppression role.

Footnotes

^‡To whom correspondence may be addressed. E-mail: j-hurwitz{at}ski.mskcc.org or haracska{at}brc.hu
Author contributions: I.U. and I.H. contributed equally to this work; I.U., S.P., and L.H. designed research; I.U., I.H., K.F., J.-H.Y., and L.H. performed research; J.H. and L.P. contributed new reagents/analytic tools; L.H. analyzed data; and I.U., S.P., and L.H. wrote the paper.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/cgi/content/full/0800563105/DC1.