CHARACTERIZATION OF A SYNECHOCOCCUS SP STRAIN PCC-7002 MUTANT LACKING PHOTOSYSTEM .1. PROTEIN ASSEMBLY AND ENERGY-DISTRIBUTION IN THE ABSENCE OF THE PHOTOSYSTEM-I REACTION-CENTER CORE COMPLEX
CHARACTERIZATION OF A SYNECHOCOCCUS SP STRAIN PCC-7002 MUTANT LACKING PHOTOSYSTEM .1. PROTEIN ASSEMBLY AND ENERGY-DISTRIBUTION IN THE ABSENCE OF THE PHOTOSYSTEM-I REACTION-CENTER CORE COMPLEX
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DOI：
10.1007/bf00018295
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发表时间：
1995-05-01
影响因子：
3.7
通讯作者：
BRYANT, DA
中科院分区：
文献类型：
--
作者：
SHEN, GZ;BRYANT, DA
通过在弱光条件下选择和分离psaA和psaB基因的缺失插入子诱变，构建了聚球藻属菌株PCC 7002 Delta psaAB：：cat突变体。该菌株能以甘油为碳源进行光合异养生长，在低光强（10 μ E·m ~（-2）·s ~（-1））下，倍增时间为25 h。在Delta psaAB：：cat突变体中没有检测到光系统I（PS I）相关的叶绿素荧光发射峰。Δ psaAB：：cat突变体的叶绿素含量在每个细胞的基础上约为野生型菌株的20%。在不存在PsaA和PsaB蛋白的情况下，其他几种PS I蛋白不会积累到正常水平。外周PS I蛋白PsaC、PsaD、PsaE和PsaL的组装依赖于PsaA和PsaB异二聚体核心的存在。PsaF的前体形式可以插入到类囊体膜中，但在PsaA和PsaB不存在的情况下不能加工成其成熟形式。PS I反应中心的缺失对光系统II（PS II）的组装和活性没有明显影响。虽然突变体表现出更大的荧光发射从藻蓝蛋白，大部分的光能吸收的藻胆体被有效地转移到PS II反应中心的PS I的情况下。在Delta psaAB：：cat菌株中未检测到轻态转变;在不存在PS I的情况下，细胞保持在状态1。这种相对耐光的菌株缺乏PS I的发展提供了一个重要的新工具PS I的遗传操作，并进一步证明了聚球藻属PCC 7002的结构和功能分析的PS I反应中心的效用。
A Synechococcus sp, strain PCC 7002 Delta psaAB::cat mutant has been constructed by deletional interposon mutagenesis of the psaA and psaB genes through selection and segregation under low-light conditions. This strain can grow photoheterotrophically with glycerol as carbon source with a doubling time of 25 h at low light intensity (10 mu E m(-2) s(-1)). No Photosystem I (PS I)-associated chlorophyll fluorescence emission peak was detected in the Delta psaAB::cat mutant. The chlorophyll content of the Delta psaAB::cat mutant was approximately 20% that of the wild-type strain on a per cell basis. In the absence of the PsaA and PsaB proteins, several other PS I proteins do not accumulate to normal levels. Assembly of the peripheral PS I proteins PsaC, PsaD, PsaE, and PsaL is dependent on the presence of the PsaA and PsaB heterodimer core. The precursor form of PsaF may be inserted into the thylakoid membrane but is not processed to its mature form in the absence of PsaA and PsaB. The absence of PS I reaction centers has no apparent effect on Photosystem II (PS II) assembly and activity. Although the mutant exhibited somewhat greater fluorescence emission from phycocyanin, most of the light energy absorbed by phycobilisomes was efficiently transferred to the PS II reaction centers in the absence of the PS I. No light state transition could be detected in the Delta psaAB::cat strain; in the absence of PS I, cells remain in state 1. Development of this relatively light-tolerant strain lacking PS I provides an important new tool for the genetic manipulation of PS I and further demonstrates the utility of Synechococcus sp. PCC 7002 for structural and functional analyses of the PS I reaction center.