Phospholipase D (PLD) is present in Leishmania donovani and its activity increases in response to acute osmotic stress
Phospholipase D (PLD) is present in Leishmania donovani and its activity increases in response to acute osmotic stress
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DOI：
10.1111/j.1550-7408.2001.tb00421.x
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发表时间：
2001-01-01
影响因子：
2.2
通讯作者：
Gomez-Cambronero, J
中科院分区：
文献类型：
--
作者：
Blum, JJ;Lehman, JA;Gomez-Cambronero, J
我们在这里报告了信号分子磷脂酶D （PLD）存在于寄生原生动物多诺瓦利什曼原虫。体外酶活性依赖于Ca2+和Mg2+离子。其基础活性受磷脂酰肌醇-4,5-二磷酸（PIP2）的刺激，其最适pH值为8.0和6.0。在渗透压从317 mOsm（等渗）突然下降到155 mOsm后约5分钟，PLD活性增加3倍，在渗透压突然增加到617 mOsm时，PLD活性增加1.5倍。在等渗条件下生长bbbb24 h的细胞与在等渗条件下生长的对照组相比，活性只有微小的变化。表明适应长期暴露于低或高渗透压环境。在免疫学上，存在PLD1和PLD2两种异构体。对体外抗PLD免疫复合物中PLD活性的分析表明，低渗（细胞肿胀）或高渗应激（细胞萎缩）导致PLD1激活增加，但PLD2活性降低。这两个同工异构体之间的相互作用导致PLD1在测量总PLD活性时观察到的增加中占主导地位。最后，在急性低渗休克中，酶活性的增加伴随着PLD1异构体的酪氨酸磷酸化，这表明蛋白酪氨酸激酶在渗透胁迫下控制PLD活性中的作用。
We report here that the signaling molecule phospholipase D (PLD) is present in the parasitic protozoan Leishmania donovani. In vitro enzymatic activity is dependent on Ca2+ and Mg2+ ions. its basal activity is stimulated by phosphatidyl-inositol-4,5-bisphosphate (PIP2), and its pH optima are pH 8.0 and pH 6.0. PLD activity increases 3-fold about 5 min after an abrupt decrease in osmolality from 317 mOsm (isosmotic) to 155 mOsm and increases 1.5-fold in response to an abrupt increase in osmolality to 617 mOsM. Cells grown for > 24 h under the anisosmotic conditions showed only marginal changes in activity compared to the controls grown under isosmotic conditions. indicating an adaptation to long-term exposure to hypo- or hyper-osmolarity. Immunologically, two isoforms, PLD1 and PLD2, are present. An analysis of in vitro PLD activity in anti-PLD immunocomplexes revealed that either hypotonic (cell swelling) or hypertonic stress (cell shrinking) causes an increase in PLD1 activation but a reduction in PLD2 activity. The interplay between these two isoforms results in a predominance for PLD1 in the observed increase when measuring total PLD activity. Finally, the increase in enzymatic activity in acute hyposmotic shock is accompanied by tyrosyl phosphorylation of the PLD1 isoform, suggesting a role for protein tyrosine kinase in the control of PLD activity in response to osmotic stress.