The RING heterodimer BRCA1-BARD1 is a ubiquitin ligase inactivated by a breast cancer-derived mutation
The RING heterodimer BRCA1-BARD1 is a ubiquitin ligase inactivated by a breast cancer-derived mutation
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DOI：
10.1074/jbc.c000881200
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发表时间：
2001-05-04
影响因子：
4.8
通讯作者：
Ohta, T
中科院分区：
文献类型：
--
作者：
Hashizume, R;Fukuda, M;Ohta, T
BRCA 1-BARD 1构成通过其N-末端区域缔合的异二聚体环指复合物。在这里，我们证明了BRCA 1-BARD 1异二聚体环指复合物含有显著的泛素连接酶活性，该活性可以被BRCA 1中的乳腺癌衍生的环指突变破坏，而单独的BRCA 1和BARD 1在体外具有非常低的泛素连接酶活性，BRCA 1与BARD 1组合表现出显着更高的活性。细菌纯化的包含BRCA 1残基1-304和BARD 1残基25-189的RING指结构域能够聚合泛素。共转染BARD 1可增加转染BRCA 1的体内稳态水平，并且BRCA 1以剂量依赖性方式增加转染BARD 1的体内稳态水平。乳腺癌来源的BARD 1相互作用缺陷突变体BRCA 1（C61 G）在体外不表现出泛素连接酶活性。这些结果表明，BRCA 1-BARD 1复合物含有泛素连接酶活性，这在预防乳腺癌和卵巢癌发展中很重要。
BRCA1-BARD1 constitutes a heterodimeric RING finger complex associated through its N-terminal regions. Here we demonstrate that the BRCA1-BARD1 heterodimeric RING finger complex contains significant ubiquitin ligase activity that can be disrupted by a breast cancer-derived RING finger mutation in BRCA1, Whereas individually BRCA1 and BARD1 have very low ubiquitin ligase activities in vitro, BRCA1 combined with BARD1 exhibits dramatically higher activity. Bacterially purified RING finger domains comprising residues 1-304 of BRCA1 and residues 25-189 of BARD1 are capable of polymerizing ubiquitin, The steady-state level of transfected BRCA1 in vivo was increased by co-transfection of BARD1, and reciprocally that of transfected BARD1 was increased by BRCA1 in a dose-dependent manner. The breast cancer-derived BARD1 interaction-deficient mutant, BRCA1(C61G), does not exhibit ubiquitin ligase activity in vitro. These results suggest that the BRCA1-BARD1 complex contains a ubiquitin ligase activity that is important in prevention of breast and ovarian cancer development.