YbbN/CnoX are proteins that display a Thioredoxin (Trx) domain linked to a tetratricopeptide domain. YbbN from (YbbN) displays a co-chaperone (holdase) activity that is induced by HOCl. Here, we compared YbbN with YbbN proteins from (YbbN) and from (YbbN). YbbN presents a redox active Cys residue at Trx domain (Cys63), 24 residues away from SQHC motif (SQHC[N]C) that can form mixed disulfides with target proteins. In contrast, YbbN and YbbN present two Cys residues in the CXXC (CAPC) motif, while only YbbN shows the Cys residue equivalent to Cys63 of YbbN. Our phylogenetic analysis revealed that most of the YbbN proteins are in the bacteria domain of life and that their members can be divided into four groups according to the conserved Cys residues. YbbN (SQHC[N]C), YbbN (CAPC[N]V) and YbbN (CAPC[N]C) are representatives of three sub-families. In contrast to YbbN, both YbbN and YbbN: (1) reduced an artificial disulfide (DTNB) and (2) supported the peroxidase activity of Peroxiredoxin Q from , suggesting that these proteins might function similarly to the canonical Trx enzymes. Indeed, YbbN was reduced by Trx reductase with a high catalytic efficiency (/K = 1.27 x 10 M s), similar to the canonical Trx (TsnC). Furthermore, YbbN and YbbN, but not YbbN displayed HOCl-induced holdase activity. Remarkably, YbbN gained disulfide reductase activity while lost the HOCl-activated chaperone function, when the SQHC was replaced by CQHC. In contrast, the YbbN CAPA mutant lost the disulfide reductase activity, while kept its HOCl-induced chaperone function. In all cases, the induction of the holdase activity was accompanied by YbbN oligomerization. Finally, we showed that deletion of gene did not render in more sensitive stressful treatments. Therefore, YbbN/CnoX proteins display distinct properties, depending on the presence of the three conserved Cys residues.

中文翻译：

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YbbN/CnoX 蛋白的功能多样性：来自铜绿假单胞菌、苛养木杆菌和大肠杆菌的三种硫氧还蛋白样氧化还原酶的比较分析的见解

YbbN/CnoX 是显示与四肽结构域相连的硫氧还蛋白 (Trx) 结构域的蛋白质。 (YbbN) 中的 YbbN 显示出由 HOCl 诱导的辅助伴侣（保持酶）活性。在这里，我们将 YbbN 与来自 (YbbN) 和 (YbbN) 的 YbbN 蛋白进行了比较。 YbbN 在 Trx 结构域 (Cys63) 处呈现氧化还原活性 Cys 残基，距 SQHC 基序 (SQHC[N]C) 24 个残基，可与靶蛋白形成混合二硫键。相比之下，YbbN 和 YbbN 在 CXXC (CAPC) 基序中存在两个 Cys 残基，而只有 YbbN 显示与 YbbN 的 Cys63 等效的 Cys 残基。我们的系统发育分析表明，大多数 YbbN 蛋白都存在于细菌的生命域中，并且根据保守的 Cys 残基，它们的成员可以分为四组。 YbbN (SQHC[N]C)、YbbN (CAPC[N]V) 和 YbbN (CAPC[N]C) 是三个亚族的代表。与 YbbN 相比，YbbN 和 YbbN 都：（1）还原了人工二硫键（DTNB），（2）支持了 Peroxiredoxin Q 的过氧化物酶活性，表明这些蛋白质的功能可能与经典的 Trx 酶类似。事实上，YbbN 被 Trx 还原酶还原，具有高催化效率 (/K = 1.27 x 10 M s)，类似于典型的 Trx (TsnC)。此外，YbbN 和 YbbN，但 YbbN 不显示 HOCl 诱导的保持酶活性。值得注意的是，当 SQHC 被 CQHC 取代时，YbbN 获得了二硫键还原酶活性，同时失去了 HOCl 激活的伴侣功能。相比之下，YbbN CAPA 突变体失去了二硫键还原酶活性，同时保留了 HOCl 诱导的伴侣功能。在所有情况下，保持酶活性的诱导都伴随着 YbbN 寡聚化。最后，我们表明基因删除并没有导致更敏感的压力治疗。因此，YbbN/CnoX 蛋白显示出不同的特性，具体取决于三个保守的 Cys 残基的存在。