Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, S-413 90 Göteborg, Sweden.
Department of Physics, Chalmers University of Technology, S-412 96 Göteborg, Sweden.
Nat Commun. 2017 Mar 24;8:14791. doi: 10.1038/ncomms14791.
Yeast lacks dedicated photoreceptors; however, blue light still causes pronounced oscillations of the transcription factor Msn2 into and out of the nucleus. Here we show that this poorly understood phenomenon is initiated by a peroxisomal oxidase, which converts light into a hydrogen peroxide (HO) signal that is sensed by the peroxiredoxin Tsa1 and transduced to thioredoxin, to counteract PKA-dependent Msn2 phosphorylation. Upon HO, the nuclear retention of PKA catalytic subunits, which contributes to delayed Msn2 nuclear concentration, is antagonized in a Tsa1-dependent manner. Conversely, peroxiredoxin hyperoxidation interrupts the HO signal and drives Msn2 oscillations by superimposing on PKA feedback regulation. Our data identify a mechanism by which light could be sensed in all cells lacking dedicated photoreceptors. In particular, the use of HO as a second messenger in signalling is common to Msn2 oscillations and to light-induced entrainment of circadian rhythms and suggests conserved roles for peroxiredoxins in endogenous rhythms.
酵母缺乏专门的光感受器;然而，蓝光仍然导致转录因子 Msn2 明显地进出细胞核的振荡。在这里，我们表明，这种理解甚少的现象是由过氧化物酶体氧化酶引发的，该氧化酶将光转化为过氧化氢（HO）信号，该信号被过氧化物还原酶 Tsa1 感知，并转导至硫氧还蛋白，以抵消 PKA 依赖性 Msn2 磷酸化。在 HO 的情况下，核保留 PKA 催化亚基，这有助于延迟 Msn2 核浓度，以 Tsa1 依赖性方式拮抗。相反，过氧化物还原酶的超氧化中断了 HO 信号，并通过叠加 PKA 反馈调节来驱动 Msn2 振荡。我们的数据确定了一种机制，通过该机制，所有缺乏专门光感受器的细胞都可以感知光。特别是，HO 作为信号转导中的第二信使，在 Msn2 振荡以及光诱导的生物钟节律同步中很常见，这表明过氧化物还原酶在内源性节律中具有保守作用。
