Friso G, Barbato R, Giacometti G M, Barber J
Dipartimento di Biologia, Universita di Padova, Italy.
FEBS Lett. 1994 Feb 21;339(3):217-21. doi: 10.1016/0014-5793(94)80419-2.
Exposure of isolated reaction centres of photosystem II to UV-B radiation generates specific breakdown products of the D2 protein. When the quinone, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone is present a 22 kDa fragment containing the N-terminus of the mature protein is generated. Concomitant with the appearance of the N-terminal fragment, two fragments containing the C-terminus of the D2 protein having apparent molecular masses around 10-12 kDa are observed. It is concluded that the primary cleavage occurs in the hydrophilic loop linking putative transmembrane segments IV and V. No such cleavage was observed when silicomolybdate was used as an electron acceptor, suggesting that this UV-B damage is dependent on binding of the added quinone to the QA site.
将光系统II的分离反应中心暴露于UV-B辐射下会产生D2蛋白的特定降解产物。当存在醌2,5-二溴-3-甲基-6-异丙基对苯醌时，会产生一个包含成熟蛋白N端的22 kDa片段。与N端片段的出现同时，观察到两个包含D2蛋白C端、表观分子量约为10 - 12 kDa的片段。得出的结论是，主要切割发生在连接假定跨膜片段IV和V的亲水环中。当使用硅钼酸盐作为电子受体时未观察到这种切割，这表明这种UV-B损伤依赖于添加的醌与QA位点的结合。
