Delineating the conformational elements responsible for Cu(2+)-induced oligomerization of beta-2 microglobulin.
Delineating the conformational elements responsible for Cu(2+)-induced oligomerization of beta-2 microglobulin.
复制标题
DOI：
10.1021/bi900540j
复制
发表时间：
2009-07-21
期刊：
影响因子：
2.9
通讯作者：
Miranker, Andrew D.
中科院分区：
文献类型：
--
作者：
Blaho, Dorottya V.;Miranker, Andrew D.
β-2 微球蛋白 (β2m) 是一种小球状蛋白，与长期血液透析治疗的肾脏患者淀粉样纤维的形成有关。在体外，生理条件下，β2m不易聚集。然而，在化学计量的 Cu2+ 存在下，β2m 很容易自缔合，最终导致尺寸不均匀的聚集体。由于该过程发生在接近生理溶液的条件下，其中折叠在未折叠状态下稳定≥20 kJ/mol，因此局部构象重排对于理解 β2m 的寡聚化至关重要。残基 32 处保守的顺式脯氨酸的异构化是该过程中公认的步骤，可以通过 Cu2+ 结合启动。为了更好地理解金属诱导的 β2m 寡聚化的结构基础，我们着手确定各个咪唑侧链在介导 P32A β2m 框架中的金属结合亲和力、天然状态稳定性和寡聚化中的作用。我们发现 P32A 在 Cu2+ 存在下以明显合作的方式形成四聚体。该四聚体的一个界面似乎沿着边缘链存在，因为 H51 是介导寡聚化的关键残基。此外，H31 是 P32A 中主要的 Cu2+ 结合残基，在稳定全息形式的蛋白质方面具有重要作用。重要的是，P32A 中的 Cu2+ 结合亲和力比 WT 中的高得多。在这里，我们证明这种强结合亲和力不需要直接与寡聚化结合。我们根据 β2mapo 的已知结构和 β2mholo 的可逆六聚态来解释我们的结果。
β–2 microglobulin (β2m) is a small globular protein implicated in amyloid fiber formation in renal patients on long-term hemodialysis therapy. In vitro, under physiological conditions, β2m is not aggregation prone. However, in the presence of stoichiometric Cu2+, β2m readily self-associates ultimately leading to heterogeneously sized aggregates. As this process occurs under near physiological solution conditions where the fold is ≥ 20 kJ/mol stabilized over the unfolded state, local conformational rearrangements are critical to understanding the oligomerization of β2m. The isomerization of a conserved cis proline at residue 32 is a recognized step in this process that can be initiated by Cu2+ binding. To better understand the structural basis of metal induced oligomerization of β2m, we set out to determine the role of individual imidazole side chains in mediating metal binding affinity, native state stability and oligomerization in the framework of P32A β2m. We find that P32A in the presence of Cu2+ forms a tetramer in an apparently cooperative manner. One interface of this tetramer appears to reside along an edge strand as H51 is a key residue in mediating oligomerization. Furthermore, H31 is the main Cu2+ binding residue in P32A and has an important role in stabilizing the protein in its holo form. Importantly, Cu2+ binding affinity in P32A is much greater than in WT. Here, we show that this strong binding affinity need not be directly coupled to oligomerization. We interpret our results in terms of the known structures of β2mapo and a reversible hexameric state of β2mholo.
登录
查看更多内容
影响因子：
64.8
作者：
COLLINS, EJ;GARBOCZI, DN;WILEY, DC
通讯作者：
WILEY, DC
影响因子：
16.8
作者：
通讯作者：
--
影响因子：
2.9
作者：
BOLEN, DW;SANTORO, MM
通讯作者：
SANTORO, MM
影响因子：
8
作者：
Antwi, Kwasi;Mahar, Maura;Vachet, Richard W.
通讯作者：
Vachet, Richard W.
影响因子：
2.9
作者：
Eakin, CM;Attenello, FJ;Miranker, AD
通讯作者：
Miranker, AD