The P_II‐like protein SbtB has been identified as a regulator of SbtA, which is one of the key bicarbonate transporters in cyanobacteria. While SbtB from Synechocystis sp. PCC 6803 has previously been shown to be a trimer, a new crystal form is reported here which crystallizes in what is thought to be a non‐native tetramer in the crystal, with the C‐terminus in an extended conformation. The crystal structure shows the formation of an intermolecular disulfide bond at Cys94 between SbtB monomers, which may stabilize this conformation in the crystal. This motivates the need for future studies to investigate the potential role that the oxidation and reduction of these cysteines may play in the activation and/or function of SbtB.

中文翻译：

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来自集胞藻属的蓝藻碳酸氢盐转运蛋白调节剂 SbtB 的四方晶型。PCC 6803。

P _II样蛋白 SbtB 已被鉴定为 SbtA 的调节剂，SbtA 是蓝藻中关键的碳酸氢盐转运蛋白之一。而来自集胞藻属的SbtB 。PCC 6803 以前已被证明是三聚体，这里报道了一种新的晶体形式，它在晶体中以被认为是非天然四聚体的形式结晶，C 端处于扩展构象。晶体结构显示在 SbtB 单体之间在 Cys94 处形成分子间二硫键，这可以稳定晶体中的这种构象。这促使未来研究需要调查这些半胱氨酸的氧化和还原可能在 SbtB 的激活和/或功能中发挥的潜在作用。