Guerra D J, Ohlrogge J B, Frentzen M
Northern Regional Research Center, Agriculture Research Service, United States Department of Agriculture, Peoria, Illinois 61604.
Plant Physiol. 1986 Oct;82(2):448-53. doi: 10.1104/pp.82.2.448.
Two forms of spinach acyl carrier protein (ACP-I and ACP-II) have recently been characterized and found to be expressed in a tissue-specific manner (JB Ohlrogge, TM Kuo, 1985 J Biol Chem 260: 8032). To examine possible different functions for these ACP isoforms, we have tested purified preparations of spinach leaf ACP-I and ACP-II and Escherichia coli ACP in several in vitro reactions of fatty acid metabolism. Total de novo fatty acid synthesis and malonyl-CoA:ACP transacylase do not appear to discriminate between acyl carrier protein isoforms. In contrast, the K(m) of oleoyl-ACP thioesterase for oleoyl-ACP-II is 10-fold higher than for oleoyl-ACP-I, whereas the K(m) of acyl-ACP glycerol-3-phosphate acyl transferase is 5-fold higher for oleoyl-ACP-I than for oleoyl-ACP-II. A characterization of these reactions and a possible role for ACP isoforms in regulation of fatty acid metabolism in plants are described.
最近已鉴定出菠菜酰基载体蛋白的两种形式(ACP-I和ACP-II),并发现它们以组织特异性方式表达(JB·奥赫罗格、TM·郭,1985年《生物化学杂志》260:8032)。为了研究这些ACP同工型可能存在的不同功能,我们在脂肪酸代谢的几个体外反应中测试了菠菜叶ACP-I和ACP-II以及大肠杆菌ACP的纯化制剂。从头合成脂肪酸总量和丙二酸单酰辅酶A:ACP转酰基酶似乎不会区分酰基载体蛋白同工型。相比之下,油酰-ACP硫酯酶对油酰-ACP-II的K(m)比对油酰-ACP-I高10倍,而酰基-ACP甘油-3-磷酸酰基转移酶对油酰-ACP-I的K(m)比对油酰-ACP-II高5倍。本文描述了这些反应的特征以及ACP同工型在植物脂肪酸代谢调节中的可能作用。