Multiple TPR motifs characterize the Fanconi anemia FANCG protein
Multiple TPR motifs characterize the Fanconi anemia FANCG protein
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DOI：
10.1016/j.dnarep.2003.09.007
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发表时间：
2004-01-05
期刊：
影响因子：
3.8
通讯作者：
Joenje, H
中科院分区：
文献类型：
--
作者：
Blom, E;van de Vrugt, HJ;Joenje, H
Fanconi贫血（FA）患者的基因组保护途径有缺陷，至少由8个基因控制，包括BRCA 2。该途径中的关键步骤涉及FANCD 2的单泛素化，其关键地依赖于至少六种FANC蛋白（FANCA、-C、-E、-F、-G和-L）的多亚基核“核心复合物”。除了具有WD 40重复序列和RING指结构域的FANCL外，迄今为止在任何核心复合物蛋白中均未发现显著的结构域结构。通过使用同源性搜索策略比较人FANCG蛋白质序列与其在Oryzias latipes（日本稻鱼）和Danio rerio（斑马鱼）中的直系同源序列，我们确定了至少7个tetratricopeptide重复基序（TPR），覆盖了该蛋白质的主要部分。TPR是简并的34-氨基酸重复基序，其充当介导蛋白质-蛋白质相互作用的支架，通常在多蛋白质复合物中发现。在测试的五个TPR基序中的四个（TPR 1、-2、-5和-6）中，靶向错义诱变破坏每个TPR的关键位置8处的基序导致FANCG功能的完全或部分丧失。功能丧失从突变蛋白未能补充FA-G成淋巴细胞中的细胞FA表型是明显的，这与FANCA结合的丧失相关。虽然TPR 4突变体完全补充了细胞，但它显示出与FANCA的相互作用减少，这表明该TPR也可能具有功能重要性。FANCG作为典型TPR蛋白的识别预测该蛋白在核FA蛋白核心复合物的组装和/或稳定中发挥关键作用。(C)2003 Elsevier B. V.保留所有权利。
The genome protection pathway that is defective in patients with Fanconi anemia (FA) is controlled by at least eight genes, including BRCA2. A key step in the pathway involves the monoubiquitylation of FANCD2, which critically depends on a multi-subunit nuclear 'core complex' of at least six FANC proteins (FANCA, -C, -E, -F, -G, and -L). Except for FANCL, which has WD40 repeats and a RING finger domain, no significant domain structure has so far been recognized in any of the core complex proteins. By using a homology search strategy comparing the human FANCG protein sequence with its ortholog sequences in Oryzias latipes (Japanese rice fish) and Danio rerio (zebrafish) we identified at least seven tetratricopeptide repeat motifs (TPRs) covering a major part of this protein. TPRs are degenerate 34-amino acid repeat motifs which function as scaffolds mediating protein-protein interactions, often found in multiprotein complexes. In four out of five TPR motifs tested (TPR1, -2, -5, and -6), targeted missense mutagenesis disrupting the motifs at the critical position 8 of each TPR caused complete or partial loss of FANCG function. Loss of function was evident from failure of the mutant proteins to complement the cellular FA phenotype in FA-G lymphoblasts, which was correlated with loss of binding to FANCA. Although the TPR4 mutant fully complemented the cells, it showed a reduced interaction with FANCA, suggesting that this TPR may also be of functional importance. The recognition of FANCG as a typical TPR protein predicts this protein to play a key role in the assembly and/or stabilization of the nuclear FA protein core complex. (C) 2003 Elsevier B.V. All rights reserved.