THE HIGHLY ABUNDANT CHLOROPHYLL-PROTEIN COMPLEX OF IRON-DEFICIENT SYNECHOCOCCUS SP PCC7942 (CP43) IS ENCODED BY THE ISIA GENE
THE HIGHLY ABUNDANT CHLOROPHYLL-PROTEIN COMPLEX OF IRON-DEFICIENT SYNECHOCOCCUS SP PCC7942 (CP43) IS ENCODED BY THE ISIA GENE
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DOI：
10.1104/pp.103.3.893
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发表时间：
1993-11-01
期刊：
影响因子：
7.4
通讯作者：
SHERMAN, LA
中科院分区：
文献类型：
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作者：
BURNAP, RL;TROYAN, T;SHERMAN, LA
一种名为CPVI-4的叶绿素-蛋白质复合体成为聚球藻的主要色素-蛋白质复合体。在铁限制条件下生长的PCC7942细胞。作者Laudenbach等人。(J Baciol[1988]170：5018-5026)已经发现了一个铁抑制操纵子，命名为isiAB，它含有黄毒素基因和一个编码类似于光系统II的CP43的CHI结合蛋白的基因。为了验证CP43样蛋白是CPVI-4复合体的一个组成部分的假设，我们在聚球藻中灭活了isiAB操纵子。PCC7942使用定向插入突变。在铁限制条件下生长的突变细胞与类似生长的野生型细胞相比，其光谱和光合作用特性发生了显著变化。值得注意的是，在685 nm处的强77K荧光发射，在缺铁野生型细胞的光谱中占主导地位，在突变体中显著减少。这一发射的损失似乎揭开了原本被遮蔽的光系统II在685和695 nm的发射。最重要的是，微变性凝胶电泳显示突变细胞不再表达CPVI-4复合体，这表明ISIA基因编码了这个丰富的Chl-蛋白质复合体的一个组成部分。
A chlorophyll (Chl)-protein complex designated CPVI-4 becomes the major pigment-protein complex in Synechococcus sp. PCC7942 cells grown under conditions of iron limitation. Work by Laudenbach et al. (J Bacteriol [1988] 170: 5018-5026) has identified an iron-repressible operon, designated isiAB, containing the flavodoxin gene and a gene predicted to encode a Chi-binding protein resembling CP43 of photosystem II. To test the hypothesis that the CP43-like protein is a component of the CPVI-4 complex, we have inactivated the isiAB operon in Synechococcus sp. PCC7942 using directed insertional mutagenesis. Mutant cells grown under conditions of iron limitation exhibit pronounced changes in their spectroscopic and photosynthetic properties relative to similarly grown wild-type cells. Notably, the strong 77 K fluorescence emission at 685 nm, which dominates the spectrum of iron-deficient wild-type cells, is dramatically reduced in the mutant. The loss of this emission appears to unmask the otherwise obscured photosystem II emissions at 685 and 695 nm. Most importantly, mildly denaturing gel electrophoresis shows that mutant cells no longer express the CPVI-4 complex, indicating that the isiA gene encodes a component of this abundant Chl-protein complex.