Peroxisomal Acyl-CoA synthetase activity is essential for seedling development in Arabidopsis thaliana
Peroxisomal Acyl-CoA synthetase activity is essential for seedling development in Arabidopsis thaliana
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DOI：
10.1105/tpc.019646
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发表时间：
2004-02-01
期刊：
影响因子：
11.6
通讯作者：
Browse, J
中科院分区：
文献类型：
--
作者：
Fulda, M;Schnurr, J;Browse, J
在植物和其他真核生物中，长链的酰基-COA被认为是通过三磷酸腺苷结合盒(ABC)转运蛋白被引入到过氧化体中进行β-氧化。然而，拟南芥中的两个基因LACS6和LACS7编码过氧化物体长链酰辅酶A合成酶(LACS)同工酶。为了研究过氧化体LACS的生化和生物学作用，我们确定了这两个基因的T-DNA敲除突变体。单突变系lacs6-1和lacs7-1在萌发、生长和生殖发育方面与野生型难以区分。相反，lacs6-1 lacs7-1双突变体在种子脂肪动员方面存在特异性缺陷，需要外源蔗糖才能成苗。这一表型与缺乏过氧体ABC转运蛋白的拟南芥pxa1突变体和其他缺乏P-氧化的突变体相似。我们的结果表明，过氧化物体LACS活性和PXA1转运蛋白是幼苗早期生长所必需的。如果PXA1转运体将未酯化的脂肪酸输送到过氧体基质中，则过氧体LACS的活性是必要的。或者，PXA1和LACS6/LACS7可能以平行的途径起作用，这两条途径都是确保为β-氧化和成功的幼苗建立提供足够的酰基辅酶A底物所必需的。
In plants and other eukaryotes, long-chain acyl-CoAs are assumed to be imported into peroxisomes for beta-oxidation by an ATP binding cassette (ABC) transporter. However, two genes in Arabidopsis thaliana, LACS6 and LACS7, encode peroxisomal long-chain acyl-CoA synthetase (LACS) isozymes. To investigate the biochemical and biological roles of peroxisomal LACS, we identified T-DNA knockout mutants for both genes. The single-mutant lines, lacs6-1 and lacs7-1, were indistinguishable from the wild type in germination, growth, and reproductive development. By contrast, the lacs6-1 lacs7-1 double mutant was specifically defective in seed lipid mobilization and required exogenous sucrose for seedling establishment. This phenotype is similar to the A. thaliana pxa1 mutants deficient in the peroxisomal ABC transporter and other mutants deficient in P-oxidation. Our results demonstrate that peroxisomal LACS activity and the PXA1 transporter are essential for early seedling growth. The peroxisomal LACS activity would be necessary if the PXA1 transporter delivered unesterified fatty acids into the peroxisomal matrix. Alternatively, PXA1 and LACS6/LACS7 may act in parallel pathways that are both required to ensure adequate delivery of acyl-CoA substrates for beta-oxidation and successful seedling establishment.