Department of Biochemistry and Center for Plant Biology, Purdue University, West Lafayette, IN, USA.
Department of Biochemistry, University of Cambridge, UK.
FEBS Lett. 2022 Jun;596(12):1533-1543. doi: 10.1002/1873-3468.14340. Epub 2022 Apr 11.
Cyanobacteria employ two-component sensor-response regulator systems to monitor and respond to environmental challenges. The response regulators RpaA, RpaB, Rre1 and RppA are integral to circadian clock function and abiotic stress acclimation in cyanobacteria. RpaA, RpaB and Rre1 are known to interact with ferredoxin or thioredoxin, raising the possibility of their thiol regulation. Here, we report that Synechocystis sp. PCC 6803 Rre1, RpaA and RpaB exist as higher-order oligomers under oxidising conditions and that reduced thioredoxin A converts them to monomers. We further show that these response regulators contain redox-responsive cysteine residues with an E around -300 mV. These findings suggest a direct thiol modulation of the activity of these response regulators, independent of their cognate sensor kinases.
蓝藻利用双组分传感器-响应调节器系统来监测和响应环境挑战。响应调节剂 RpaA、RpaB、Rre1 和 RppA 是生物钟功能和蓝藻非生物胁迫适应的重要组成部分。已知 RpaA、RpaB 和 Rre1 与铁氧还蛋白或硫氧还蛋白相互作用，这增加了它们巯基调节的可能性。在这里，我们报告说，在氧化条件下，集胞藻 PCC 6803 的 Rre1、RpaA 和 RpaB 作为更高阶的寡聚体存在，并且还原型硫氧还蛋白 A 将它们转化为单体。我们进一步表明，这些响应调节剂包含氧化还原响应的半胱氨酸残基，其 E 值在-300 mV 左右。这些发现表明，这些响应调节剂的活性可以直接进行巯基调节，而不依赖于它们的同源传感器激酶。
