Regulation of phosphatidylserine decarboxylase in Saccharomyces cerevisiae by inositol and choline: kinetics of repression and derepression.
Regulation of phosphatidylserine decarboxylase in Saccharomyces cerevisiae by inositol and choline: kinetics of repression and derepression.
复制标题
肌醇和胆碱对酿酒酵母中磷脂酰丝氨酸脱羧酶的调节：抑制和去抑制的动力学。
DOI：
10.1016/0003-9861(91)90574-3
复制
发表时间：
1991
影响因子：
3.9
通讯作者：
Waechter,CJ
中科院分区：
文献类型：
--
作者：
Overmeyer,JH;Waechter,CJ
在酿酒酵母（Saccharomycescerevisiae，G. M.卡曼和S. A.亨利，1989年，《年鉴》。Rev.Biochem.58，635-669）。在这项研究中，PS脱羧酶的活性被证明是部分抑制时，肌醇被添加到细胞的培养基中的对数生长期，和镇压的程度增加了胆碱的列入，但不是乙醇胺。PS脱羧酶，PS合成酶，和磷脂N-甲基转移酶（PNMT）的活动，作为调节反应的外源肌醇和胆碱的可用性的阻遏和去阻遏的动力学，已被表征。当肌醇被添加到呈指数增长的细胞培养物的培养基中时，三种生物合成酶的活性达到中等水平的抑制（对照的50-85%）。在加入肌醇和胆碱的组合后，PS脱羧酶，PS合成酶，PNMT活性在60 min内降至中等抑制水平，随后在调节后期（2-3 h）降至对照值的15-40%。在去阻遏研究中，从生长培养基中去除胆碱和/或肌醇后，这三种酶的活性保持相对稳定约60 min，但PS脱羧酶、PS合成酶和PNMT的比活性在2-3 h内增加到最大去阻遏水平。放线菌酮能阻断这三种生物合成活性的诱导，而氯霉素则不能。综上所述，肌醇部分可逆地抑制了产酸链霉菌PS脱羧酶的活性，肌醇和胆碱的联合作用进一步降低了PS脱羧酶的活性。肌醇和胆碱抑制的双相动力学表明，胆碱的作用取决于肌醇介导的早期事件，并且可能涉及单独的调节因子。
The biosynthesis of phosphatidylserine (PS) and its conversion to phosphatidylcholine (PC) are regulated coordinately by inositol and choline inSaccharomyces cerevisiae(G. M. Carman and S. A. Henry, 1989,Annu. Rev. Biochem.58, 635–669). In this study, PS decarboxylase activity is shown to be partially repressed when inositol is added to the medium of cells in the log phase of growth, and the extent of repression is augmented by the inclusion of choline, but not ethanolamine. The kinetics of repression and derepression of PS decarboxylase, PS synthase, and phospholipidN-methyltransferase (PNMT) activities, as regulatory responses to the availability of exogenous inositol and choline, have been characterized. When inositol was added to the medium of cell cultures growing exponentially, the three biosynthetic enzyme activities reached an intermediate level of repression (50–85% of control) within 60 min. After the addition of the combination of inositol and choline, PS decarboxylase, PS synthase, and PNMT activities decreased to the intermediate levels of repression in 60 min and were subsequently reduced to 15–40% of control values during a later stage of regulation (2–3 h). In a derepression study, the three enzyme activities remained relatively stable for approximately 60 min following the removal of choline and/or inositol from the growth medium, but the specific activities of PS decarboxylase, PS synthase, and PNMT increased to maximally derepressed levels within 2–3 h. The induction of the three biosynthetic activities was blocked by cycloheximide, but not by chloramphenicol. In summary, the level of PS decarboxylase activity inS. cerevisiaeis partially and reversibly suppressed by inositol and further diminished by the combination of inositol and choline. The biphasic kinetics of repression by inositol and choline suggest that the effect of choline is dependent on earlier events mediated by inositol and possibly involves a separate regulatory factor(s).