Phosphate availability affects the thylakoid lipid composition and the expression of SQD1, a gene required for sulfolipid biosynthesis in Arabidopsis thaliana
Phosphate availability affects the thylakoid lipid composition and the expression of SQD1, a gene required for sulfolipid biosynthesis in Arabidopsis thaliana
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DOI：
10.1073/pnas.95.4.1950
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发表时间：
1998-02-17
影响因子：
11.1
通讯作者：
Benning, C
中科院分区：
文献类型：
--
作者：
Essigmann, B;Güler, S;Benning, C
高等植物的光合膜除了普遍存在的磷脂酰甘油外，还含有特定的非磷脂质，如磺基喹诺糖基二酰甘油。在细菌中，显著影响类囊体脂质组成的环境因素似乎是磷酸盐的可用性。因此，我们发现在磷酸盐含量减少的培养基上生长的拟南芥中，以及在A.为了研究所观察到的脂质组成变化的分子基础，我们分离了一个A. thaliana的cDNA。Thaliana，命名为SQD 1，其编码参与硫脂生物合成的蛋白质，如三条证据所示，首先，cDNA显示出与已知为硫脂生物合成所必需的细菌sqdB基因的高度序列相似性，其次，SQD 1基因产物被输入到发生硫脂生物合成的叶绿体中;第三，以反义方向表达SQD 1的转基因植物显示出硫脂含量的降低。在pho 1突变体以及野生型植物生长下，磷酸盐的可用性降低，增加量的SQD 1 mRNA和SQD 1蛋白被检测到，这表明在磷酸盐限制下硫脂含量的增加是一个增加的表达所需的至少一个基因在A。thaliana.有人建议，一定量的阴离子类囊体脂质保持在减少磷酸盐的可用性下，通过取代磷脂酰甘油磺脂。
Photosynthetic membranes of higher plants contain specific nonphosphorous lipids like the sulfolipid sulfoquinovosyl diacylglycerol in addition to the ubiquitous phospholipid phosphatidylglycerol. In bacteria, an environmental factor that drastically affects thylakoid lipid composition appears to be the availability of phosphate, Accordingly, we discovered an increase in the relative amount of sulfolipid and a concomitant decrease in phosphatidylglycerol in Arabidopsis thaliana grown on medium with reduced amounts of phosphate, as well as in the pho1 mutant of A. thaliana deficient in phosphate transport, To investigate the molecular basis of the observed change in lipid composition, we isolated a cDNA of A. thaliana, designated SQD1, that encodes a protein involved in sulfolipid biosynthesis as suggested by three lines of evidence, First, the cDNA shows high sequence similarity to bacterial sqdB genes known to be essential for sulfolipid biosynthesis; second, the SQD1 gene product is imported into chloroplasts where sulfolipid biosynthesis takes place; and third, transgenic plants expressing SQD1 in antisense orientation show a reduction in sulfolipid content. In the pho1 mutant as well as in wild-type plants grown under reduced phosphate availability, increased amounts of SQD1 mRNA and SQD1 protein are detected, suggesting that the increase in sulfolipid content under phosphate limitation is the result of an increased expression of at least one gene required for sulfolipid biosynthesis in A. thaliana. It is suggested that a certain amount of anionic thylakoid lipid is maintained by substituting sulfolipid for phosphatidylglycerol under reduced phosphate availability.