Department of Chemistry, Umeå University, SE-901 87, Umeå, Sweden.
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-901 87, Umeå, Sweden.
Sci Rep. 2017 Dec 7;7(1):17151. doi: 10.1038/s41598-017-17044-3.
Peroxiredoxins (Prxs) are vital regulators of intracellular reactive oxygen species levels in all living organisms. Their activity depends on one or two catalytically active cysteine residues, the peroxidatic Cys (C) and, if present, the resolving Cys (C). A detailed catalytic cycle has been derived for typical 2-Cys Prxs, however, little is known about the catalytic cycle of 1-Cys Prxs. We have characterized Prx6 from the cyanobacterium Anabaena sp. strain PCC7120 (AnPrx6) and found that in addition to the expected peroxidase activity, AnPrx6 can act as a molecular chaperone in its dimeric state, contrary to other Prxs. The AnPrx6 crystal structure at 2.3 Å resolution reveals different active site conformations in each monomer of the asymmetric obligate homo-dimer. Molecular dynamic simulations support the observed structural plasticity. A FSH motif, conserved in 1-Cys Prxs, precedes the active site PxxxTxxCp signature and might contribute to the 1-Cys Prx reaction cycle.
过氧化物酶（Prxs）是所有生物体内细胞内活性氧水平的重要调节剂。它们的活性取决于一个或两个催化活性半胱氨酸残基，即过氧催化半胱氨酸（C）和，如果存在的话，解决半胱氨酸（C）。已经为典型的 2-Cys Prxs 推导了详细的催化循环，但是对于 1-Cys Prxs 的催化循环知之甚少。我们已经对来自蓝藻 Anabaena sp. 菌株 PCC7120 的 Prx6 进行了表征（AnPrx6），并发现除了预期的过氧化物酶活性外，AnPrx6 可以在其二聚体状态下作为分子伴侣发挥作用，这与其他 Prxs 不同。AnPrx6 的晶体结构在 2.3 Å 分辨率下揭示了不对称必需同型二聚体每个单体中不同的活性位点构象。分子动力学模拟支持观察到的结构可塑性。FSH 基序，在 1-Cys Prxs 中保守，位于活性位点 PxxxTxxCp 特征之前，可能有助于 1-Cys Prx 反应循环。
