Keegan F P, Blum J J
Department of Biology, Guilford College, Greensboro, North Carolina 27410.
J Eukaryot Microbiol. 1993 Nov-Dec;40(6):730-2. doi: 10.1111/j.1550-7408.1993.tb04467.x.
Leishmania donovani promastigotes in late-stationary phase incorporated label from [2-14C]acetate and [1-14C]laurate into the mannose residues of mannan, thus confirming the presence of a functional glyoxylate bypass in these parasitic protozoa. Isolated, washed calls also incorporated label from [2-14C]acetate and [1-14C]laurate into mannan during a 1-hr incubation in buffer. Glucose had no effect on label incorporation into mannan, but glutamate caused over a four-fold increase in incorporation from [2-14C]acetate and a 2.4-fold increase from [1-14C]laurate. Staurosporine, a protein kinase inhibitor that inhibits glutamate and alanine oxidation, did not inhibit label incorporation from [2-14C]acetate into mannan. Hyperosmolality caused about a 33% inhibition of label incorporation into mannan. These results show the glyoxylate cycle and/or the subsequent biosynthetic pathway from fructose-6-phosphate to mannan are subject to regulation.
处于静止后期的杜氏利什曼原虫前鞭毛体将[2-¹⁴C]乙酸盐和[1-¹⁴C]月桂酸盐中的标记物掺入甘露聚糖的甘露糖残基中，从而证实这些寄生原生动物中存在功能性乙醛酸支路。分离并洗涤后的细胞在缓冲液中孵育1小时期间，也能将[2-¹⁴C]乙酸盐和[1-¹⁴C]月桂酸盐中的标记物掺入甘露聚糖。葡萄糖对标记物掺入甘露聚糖没有影响，但谷氨酸盐使[2-¹⁴C]乙酸盐的掺入量增加了四倍多，使[1-¹⁴C]月桂酸盐的掺入量增加了2.4倍。星形孢菌素是一种抑制谷氨酸和丙氨酸氧化的蛋白激酶抑制剂，它并不抑制[2-¹⁴C]乙酸盐中标记物掺入甘露聚糖。高渗性导致标记物掺入甘露聚糖的量受到约33%的抑制。这些结果表明，乙醛酸循环和/或从6-磷酸果糖到甘露聚糖的后续生物合成途径受到调控。
