Passaquet C, Lichtl C
Laboratoire de Photorégulation et Dynamique des Membranes Végétales, Ecole Normale Supérieure, Centre National de la Recherche Scientifique URA 1810, Paris, France.
Plant Mol Biol. 1995 Oct;29(1):135-48. doi: 10.1007/BF00019125.
We have isolated a gene from a library of nuclear DNA for a chlorophyll a/c-binding protein (named Cac for chl a/c by analogy with Cab for chl a/b) of a chromophyte alga, Giraudyopsis stellifer, and sequenced it. The comparison of the deduced amino acid sequence with other chl a/c- and chl a/b-binding protein sequences shows that structural and functional features, i.e. the arrangement 'en X' of the two A and B transmembrane helices and the putative chl a-binding sites, are shared by both Chlorophyta and Chromophyta. Moreover, in contrast to Chlorophyta, a very strong identity is found among Chromophyta in the C helix suggesting a major function associated to this specific region. Nevertheless, the primary structure of the apoprotein does not seem affected by the pigment composition in Chromophyta. As in the few other examples currently known, we confirm that the cac genes are nuclear-encoded and are part of a multigenic family. Northern blots, performed on poly(A)+ mRNA from G: stellifer, give evidence that the cac gene is light-induced at a transcriptional level and that no expression can be observed in the dark.
我们从一种色藻（星状吉罗德藻）的核DNA文库中分离出一个编码叶绿素a/c结合蛋白（类比于叶绿素a/b结合蛋白Cab，命名为Cac）的基因，并对其进行了测序。将推导的氨基酸序列与其他叶绿素a/c和叶绿素a/b结合蛋白序列进行比较，结果表明，绿藻门和色藻门都具有结构和功能特征，即两个A和B跨膜螺旋的“X形”排列以及假定的叶绿素a结合位点。此外，与绿藻门不同的是，在色藻门的C螺旋中发现了非常高的同源性，这表明该特定区域具有主要功能。然而，脱辅基蛋白的一级结构似乎不受色藻门色素组成的影响。正如目前已知的其他少数例子一样，我们证实cac基因是核编码的，并且是多基因家族的一部分。对星状吉罗德藻的聚腺苷酸加尾mRNA进行的Northern印迹分析表明，cac基因在转录水平上受光诱导调控，在黑暗中未观察到表达。
