Distinct constitutive and low-CO2-induced CO2 uptake systems in cyanobacteria:: Genes involved and their phylogenetic relationship with homologous genes in other organisms
Distinct constitutive and low-CO2-induced CO2 uptake systems in cyanobacteria:: Genes involved and their phylogenetic relationship with homologous genes in other organisms
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DOI：
10.1073/pnas.191258298
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发表时间：
2001-09-25
影响因子：
11.1
通讯作者：
Ogawa, T
中科院分区：
文献类型：
--
作者：
Shibata, M;Ohkawa, H;Ogawa, T
蓝藻具有一种集中二氧化碳的机制，包括主动吸收二氧化碳和运输HCO3-。对于二氧化碳的吸收，我们已经在聚球藻中鉴定出两个系统。PCC6803菌株，一株低二氧化碳诱导菌和一株原生菌。低CO2诱导体系表现出比原生体系更高的最大活性和对CO2的亲和力。在推测单独的NAD(P)H脱氢酶复合体对每个系统都是必不可少的基础上，我们推断，一个系统的失活将允许选择在另一个系统中有缺陷的突变体。因此，用含有转座子的文库转化Delta ndhD3突变体后，不能在空气中生长的突变体被恢复。其中4个在slr1302(指定为cupB)内有标签，slr1302是sll1734(CuPA)的同源物，它与ndhF3和ndhD3共转录。Delta cub B、Delta ndhD4和Delta ndhF4突变体表现出野生型低CO2诱导系统的CO2吸收特征。相比之下，突变株Delta cupa、Delta ndhD3和Delta ndhF3表现出结构性CO2吸收系统的特征。在每个系统的一个成分中受损的双突变株不能吸收二氧化碳，需要高二氧化碳才能生长。系统发育分析表明，ndhD3/ndhD4-、ndhF3/ndhF4-和cupA/cub型基因仅存在于蓝藻中。所研究的大多数蓝藻菌株都具有ndhD3/ndhD4-、ndhF3/ndhF4-和cuPA/cub型基因对。因此，两种类型的NAD(P)H脱氢酶复合体对于低CO2诱导和结构性CO2吸收系统至关重要，分别与NdhD3/NdhF3/CuPA-同系物和NdhD4/NdhF4/CupB-同系物相关，似乎存在于这些蓝藻菌株中，而在其他生物中不存在。
Cyanobacteria possess a CO2-concentating mechanism that involves active CO2 uptake and HCO3- transport. For CO2 uptake, we have identified two systems in the cyanobacterium Synechocystis sp. strain PCC 6803, one induced at low CO2 and one constitutive. The low CO2-induced system showed higher maximal activity and higher affinity for CO2 than the constitutive system. On the basis of speculation that separate NAD(P)H dehydrogenase complexes were essential for each of these systems, we reasoned that inactivation of one system would allow selection of mutants defective in the other. Thus, mutants unable to grow at pH 7.0 in air were recovered after transformation of a Delta ndhD3 mutant with a transposon-bearing library. Four of them had tags within slr1302 (designated cupB), a homologue of sll1734 (cupA), which is cotranscribed with ndhF3 and ndhD3. The Delta cupB, Delta ndhD4, and Delta ndhF4 mutants showed CO2-uptake characteristics of the low CO2-induced system observed in wild type. In contrast, mutants Delta cupA, Delta ndhD3, and Delta ndhF3 showed characteristics of the constitutive CO2-uptake system. Double mutants impaired in one component of each of the systems were unable to take up CO2 and required high CO2 for growth. Phylogenetic analysis indicated that the ndhD3/ndhD4-, ndhF3/ndhF4-, and cupA/cupB-type genes are present only in cyanobacteria. Most of the cyanobacterial strains studied possess the ndhD3/ndhD4-, ndhF3/ndhF4-, and cupA/cupB-type genes in pairs. Thus, the two types of NAD(P)H dehydrogenase complexes essential for low CO2-induced and constitutive CO2-uptake systems associated with the NdhD3/NdhF3/CupA-homologues and NdhD4/NdhF4/CupB-homologues, respectively, appear to be present in these cyanobacterial strains but not in other organisms.