School of Biological Sciences, The University of Hong Kong, Hong Kong, China.
Plant Signal Behav. 2009 Nov;4(11):1063-5. doi: 10.4161/psb.4.11.9718. Epub 2009 Nov 3.
In our recent paper in Plant Physiology and Biochemistry, we reported that the mRNAs encoding Arabidopsis thaliana cytosolic acyl-CoA-binding proteins, ACBP4 and ACBP5, but not ACBP6, are modulated by light/dark cycling. The pattern of circadian-regulated expression in ACBP4 and ACBP5 mRNAs resembles that of FAD7 which encodes omega-3-fatty acid desaturase, an enzyme involved in plastidial fatty acid biosynthesis. Recombinant ACBP4 and ACBP5 proteins were observed to bind oleoyl-CoA ester comparably better than recombinant ACBP6, suggesting that ACBP4 and ACBP5 are promising candidates in the trafficking of oleoyl-CoA from the plastids to the endoplasmic reticulum (ER) for the biosynthesis of non-plastidial membrane lipids. By western blot analyses using the ACBP4 and ACBP5-specific antibodies, we show herein that the levels of ACBP4 and ACBP5 proteins peak at the end of the light period, further demonstrating that they, like their corresponding mRNAs, are tightly controlled by light to satisfy demands of lipids in plant cells.
在我们最近发表在《植物生理学与生物化学》上的一篇论文中，我们报告了拟南芥细胞质酰基辅酶 A 结合蛋白 ACBP4 和 ACBP5 的 mRNA 受到光/暗循环的调控，但 ACBP6 的 mRNA 则不受调控。ACBP4 和 ACBP5 mRNA 的昼夜节律表达模式与编码ω-3 脂肪酸去饱和酶的 FAD7 相似，后者是参与质体脂肪酸生物合成的一种酶。我们观察到重组的 ACBP4 和 ACBP5 蛋白与油酰基辅酶 A 酯的结合能力明显优于重组的 ACBP6，这表明 ACBP4 和 ACBP5 是质体向内质网（ER）转运油酰基辅酶 A 以合成非质体膜脂的有前途的候选蛋白。通过使用 ACBP4 和 ACBP5 特异性抗体的 Western blot 分析，我们在此证明 ACBP4 和 ACBP5 蛋白的水平在光照期结束时达到峰值，进一步表明它们与相应的 mRNA 一样，受到光的严格调控，以满足植物细胞中脂质的需求。
