Carnegie Institution of Washington, Stanford, California 94305.
Plant Physiol. 1990 Feb;92(2):514-9. doi: 10.1104/pp.92.2.514.
Photoinhibition resistance exhibited by the high intertidal red alga Porphyra perforata relative to its subtidal congener Porphyra nereocystis was examined using the protein synthesis inhibitor chloramphenicol to separate the damage and repair components of photoinhibition. Under photoinhibitory conditions, the rates of both damage to and replacement of photoinhibition-sensitive proteins was much higher in P. nereocystis than in P. perforata. Thus, photoinhibition resistance in P. perforata appears to be due to a reduced rate of photoinhibition damage rather than to an accelerated rate of photoinhibition repair. Reduction of photoinhibition damage in P. perforata may be by means of biophysical processes which increase the radiationless decay of excitation to heat in photosystem II. Alternatively, the photoinhibition-sensitive proteins in P. perforata may have slight structural alterations that improve their stability or they may be protected by enzyme systems that quench radicals formed by overexcitation of photosystem II. Reduction of the damage component of photoinhibition is a reasonable way to limit photoinhibition in P. perforata during the severe desiccation and exposure to full sun that occur simultaneously during daily low tides, conditions under which the protein synthesis required for photoinhibition repair could not occur.
用蛋白合成抑制剂氯霉素将光抑制的损伤和修复成分分开，研究了高光潮带红藻孔石莼相对于其亚潮带同种植物条斑紫菜的光抑制抗性。在光抑制条件下，P. nereocystis 中光抑制敏感蛋白的损伤和替代速率均远高于 P. perforata。因此，P. perforata 的光抑制抗性似乎是由于光抑制损伤的速率降低，而不是光抑制修复的速率加快。P. perforata 中光抑制损伤的减少可能是通过增加光系统 II 中激发的非辐射衰减为热的生物物理过程实现的。或者，P. perforata 中的光抑制敏感蛋白可能具有轻微的结构改变，从而提高其稳定性，或者它们可能受到酶系统的保护，该酶系统可以猝灭光系统 II 过激发形成的自由基。减少光抑制的损伤成分是在每日低潮期间同时发生的严重干燥和暴露在全日照下限制 P. perforata 中光抑制的一种合理方法，在这种条件下，光抑制修复所需的蛋白质合成无法进行。
