Murthy S N Prasanna, Chung Paul H, Lin Li, Lomasney Jon W
Department of Pathology, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611, USA.
Biochemistry. 2006 Sep 12;45(36):10987-97. doi: 10.1021/bi060648+.
This paper uses phospholipase Cepsilon as a model to demonstrate that lipids can act as ligands to bind to specific motifs and regulate protein activity via allosteric effects. Phospholipids such as phosphatidic acid and free fatty acids such as arachidonate are potent activators of PLCepsilon, increasing the rate of PI hydrolysis by 8-fold and 50-fold, respectively. The mechanism appears to be a reduction of K(m), as the substrate dependence curve is shifted to the left and K(m) is reduced 10-fold. The regulation of PLCepsilon by lipids appears to be physiologic, as reconstitution or cotransfection of either cPLA(2) or PLD with PLCepsilon leads to activation of phosphodiesterase activity. Additionally, TSA-201 cells transfected with PLCepsilon and fed arachidonic acid complexed with BSA had increased (4-5-fold) hydrolysis of polyphosphoinositides. This study demonstrates the ability of lipids to act as potent and direct mediators of protein function and identifies cross talk between different classes of phospholipase (PLD and PLA(2) with PLC) mediated via lipid products.
本文以磷脂酶Cε为模型，证明脂质可作为配体结合特定基序，并通过变构效应调节蛋白质活性。磷脂如磷脂酸和游离脂肪酸如花生四烯酸是磷脂酶Cε的有效激活剂，分别使磷脂酰肌醇水解速率提高8倍和50倍。其机制似乎是米氏常数（Km）的降低，因为底物依赖性曲线向左移动且Km降低了10倍。脂质对磷脂酶Cε的调节似乎具有生理性，因为cPLA(2)或PLD与磷脂酶Cε的重组或共转染会导致磷酸二酯酶活性的激活。此外，用磷脂酶Cε转染并喂食与牛血清白蛋白复合的花生四烯酸的TSA - 201细胞，其多磷酸肌醇的水解增加了（4 - 5倍）。本研究证明了脂质作为蛋白质功能的有效直接介质的能力，并确定了通过脂质产物介导的不同磷脂酶类别（PLD和PLA(2)与PLC）之间的相互作用。
