DDB2, the xeroderma pigmentosum group E gene product, is directly ubiquitylated by Cullin 4A-based ubiquitin ligase complex

ABSTRACT UV-damaged-DNA-binding protein (UV-DDB) is a heterodimer comprised of DDB1 and DDB2 and integrated in a complex that includes a ubiquitin ligase component, cullin 4A, and Roc1. Here we show that the ubiquitin ligase activity of the DDB2 complex is required for efficient global genome nucleotide excision repair (GG-NER) in chromatin. Mutant DDB2 proteins derived from xeroderma pigmentosum group E patients are not able to mediate ubiquitylation around damaged sites in chromatin. We also found that CSN, a negative regulator of cullin-based ubiquitin ligases, dissociates from the DDB2 complex when the complex binds to damaged DNA and that XPC and Ku oppositely regulate the ubiquitin ligase activity, especially around damaged sites. Furthermore, the DDB2 complex-mediated ubiquitylation plays a role in recruiting XPA to damaged sites. These findings shed some light on the early stages of GG-NER.

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The Cullin 4A/B-DDB1-Cereblon E3 Ubiquitin Ligase Complex Mediates the Degradation of CLC-1 Chloride Channels

Scientific Reports ◽

10.1038/srep10667 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 32

Author(s):

Yi-An Chen ◽

Yi-Jheng Peng ◽

Meng-Chun Hu ◽

Jing-Jia Huang ◽

Yun-Chia Chien ◽

...

Keyword(s):

Ubiquitin Ligase ◽

Chloride Channels ◽

E3 Ubiquitin Ligase ◽

Ubiquitin Ligase Complex ◽

Cullin 4A

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The Xeroderma Pigmentosum Group E Gene Product DDB2 Activates Nucleotide Excision Repair by Regulating the Level of p21Waf1/Cip1

Molecular and Cellular Biology ◽

10.1128/mcb.00880-07 ◽

2007 ◽

Vol 28 (1) ◽

pp. 177-187 ◽

Cited By ~ 32

Author(s):

Tanya Stoyanova ◽

Taewon Yoon ◽

Dragana Kopanja ◽

Margalit B. Mokyr ◽

Pradip Raychaudhuri

Keyword(s):

Gene Product ◽

Nucleotide Excision Repair ◽

Xeroderma Pigmentosum ◽

Excision Repair ◽

Genetic Evidence ◽

Nuclear Accumulation ◽

E Gene ◽

Nucleotide Excision

ABSTRACT The xeroderma pigmentosum group E gene product DDB2, a protein involved in nucleotide excision repair (NER), associates with the E3 ubiquitin ligase complex Cul4A-DDB1. But the precise role of these interactions in the NER activity of DDB2 is unclear. Several models, including DDB2-mediated ubiquitination of histones in UV-irradiated cells, have been proposed. But those models lack clear genetic evidence. Here we show that DDB2 participates in NER by regulating the cellular levels of p21Waf1/Cip1. We show that DDB2 enhances nuclear accumulation of DDB1, which binds to a modified form of p53 containing phosphorylation at Ser18 (p53S18P) and targets it for degradation in low-dose-UV-irradiated cells. DDB2−/− mouse embryonic fibroblasts (MEFs), unlike wild-type MEFs, are deficient in the proteolysis of p53S18P. Accumulation of p53S18P in DDB2−/− MEFs causes higher expression p21Waf1/Cip1. We show that the increased expression of p21Waf1/Cip1 is the cause NER deficiency in DDB2−/− cells because deletion or knockdown of p21Waf1/Cip1 reverses their NER-deficient phenotype. p21Waf1/Cip1 was shown to bind PCNA, which is required for both DNA replication and NER. Moreover, an increased level of p21Waf1/Cip1 was shown to inhibit NER both in vitro and in vivo. Our results provide genetic evidence linking the regulation of p21Waf1/Cip1 to the NER activity of DDB2.

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