Certain cyanobacteria synthesize chlorophyll molecules (Chl d and Chl f) that absorb in the far-red region of the solar spectrum, thereby extending the spectral range of photosynthetically active radiation^1,2. The synthesis and introduction of these far-red chlorophylls into the photosynthetic apparatus of plants might improve the efficiency of oxygenic photosynthesis, especially in far-red enriched environments, such as in the lower regions of the canopy³. Production of Chl f requires the ChlF subunit, also known as PsbA4 (ref. ⁴) or super-rogue D1 (ref. ⁵), a paralogue of the D1 subunit of photosystem II (PSII) which, together with D2, bind cofactors involved in the light-driven oxidation of water. Current ideas suggest that ChlF oxidizes Chl a to Chl f in a homodimeric ChlF reaction centre (RC) complex and represents a missing link in the evolution of the heterodimeric D1/D2 RC of PSII (refs. ^4,6). However, unambiguous biochemical support for this proposal is lacking. Here, we show that ChlF can substitute for D1 to form modified PSII complexes capable of producing Chl f. Remarkably, mutation of just two residues in D1 converts oxygen-evolving PSII into a Chl f synthase. Overall, we have identified a new class of PSII complex, which we term ‘super-rogue’ PSII, with an unexpected role in pigment biosynthesis rather than water oxidation.

某些蓝藻合成叶绿素分子（Chl d和 Chl f），在太阳光谱的远红色区域吸收，从而扩展光合有效辐射^1,2的光谱范围。这些远红色叶绿素的合成和引入植物的光合作用装置可能会提高含氧光合作用的效率，尤其是在富含远红色的环境中，例如在树冠³的下部区域。Chl f 的生产需要 ChlF 亚基，也称为 PsbA4（参考文献⁴）或超级流氓 D1（参考文献⁵)，光系统 II (PSII) 的 D1 亚基的旁系同源物，它与 D2 一起结合参与光驱动水氧化的辅助因子。当前的想法表明CHLF直接氧化叶绿素一个到叶绿素˚F在一个同型二聚体CHLF反应中心（RC）配合物和表示PSII的异二聚体D1 / D2 RC演变的缺失的环节（参考文献^4,6）。然而，该提议缺乏明确的生化支持。在这里，我们表明 ChlF 可以替代 D1 形成能够产生 Chl f 的修饰的 PSII 复合物。值得注意的是，D1 中仅两个残基的突变将释放氧的 PSII 转化为 Chl f合酶。总的来说，我们已经确定了一类新的 PSII 复合物，我们将其称为“超级流氓”PSII，在色素生物合成而不是水氧化中具有意想不到的作用。