Dss1 Release Activates DNA Binding Potential in Brh2

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• 作者：Qingwen Zhou ; Milorad Kojic ; William K. Holloman
• 刊名：Biochemistry
• 出版年：2012
• 出版时间：November 13, 2012
• 年：2012
• 卷：51
• 期：45
• 页码：9137-9146
• 全文大小：525K
• 年卷期：v.51,no.45(November 13, 2012)
• ISSN：1520-4995

文摘

Dss1 is an intrinsically unstructured polypeptide that partners with the much larger Brh2 protein, the BRCA2 ortholog in Ustilago maydis, to form a tight complex. Mutants lacking Dss1 have essentially the same phenotype as mutants defective in Brh2, implying that through physical interaction Dss1 serves as a positive activator of Brh2. Dss1 associates with Brh2 through an interaction surface in the carboxy-terminal region. Certain derivatives of Brh2 lacking this interaction surface remain highly competent in DNA repair as long as a DNA-binding domain is present. However, the Dss1-independent activity raises the question of what function might be met in the native protein by having Brh2 under Dss1 control. Using a set of Brh2 fusions and truncated derivatives, we show here that Dss1 is capable of exerting control when there is a cognate Dss1-interacting surface present. We find that association of Dss1 attenuates the DNA binding potential of Brh2 and that the amino-terminal domain of Brh2 helps evict Dss1 from its carboxy-terminal interaction surface. The findings presented here add to the notion that Dss1 serves in a regulatory capacity to dictate order in association of Brh2's amino-terminal and carboxy-terminal domains with DNA.