Lehner Christine, Kerschbaum Hubert H, Lütz-Meindl Ursula
Cell Biology Department, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria.
J Plant Physiol. 2009 Jan 30;166(2):117-27. doi: 10.1016/j.jplph.2008.02.012. Epub 2008 May 2.
Nitric oxide (NO), a key molecule in inter- and intracellular signalling, is implicated in developmental processes, host defense, and apoptosis in higher plants. We investigated the effect of NO on development in the unicellular green alga, Micrasterias denticulata, using two different NO donors, S-nitroso-N-acetyl-dl-penicillamine (SNAP) and sodium nitroprusside (SNP). Investigations at the light microsopic level revealed that both NO donors suppressed cell growth. Ultrastructural analyses were performed with SNAP- as well as SNP-treated cells and, additionally, with the control compound N-acetyl-d-penicillamine (NAP). Cells incubated with NO donors lacked a secondary wall and dictyosomal function was impaired, whereas NAP-treated cells showed no difference in development and organelle structure compared to control cells. Moreover, cisternae of the Golgi stacks were slightly involute and no vesicles were pinched off after SNAP and SNP incubation. The NO scavenger cPTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, potassium salt) abrogated the effect of SNP, thus confirming that inhibition of cell growth is due to nitric oxide. Addition of iodoacetic acid, an inhibitor of cysteine-containing enzymes, like glyceraldehyde-3-phosphate dehydrogenase (GAPDH), evoked similar effects on cell growth and secondary wall formation as obtained by treatment with NO donors. Therefore, we hypothesize that NO inhibits activity of enzymes involved in the secretory pathway, such as GAPDH, via S-nitrosylation of the cysteine residue and, consequently, modulates cell growth in M. denticulata.
一氧化氮（NO）是细胞间和细胞内信号传导中的关键分子，参与高等植物的发育过程、宿主防御和细胞凋亡。我们使用两种不同的NO供体，即S-亚硝基-N-乙酰-dl-青霉胺（SNAP）和硝普钠（SNP），研究了NO对单细胞绿藻齿状微星鼓藻发育的影响。光学显微镜水平的研究表明，两种NO供体均抑制细胞生长。我们对经SNAP和SNP处理的细胞以及对照化合物N-乙酰-d-青霉胺（NAP）处理的细胞进行了超微结构分析。与对照细胞相比，用NO供体处理的细胞缺乏次生壁，高尔基体功能受损，而经NAP处理的细胞在发育和细胞器结构上没有差异。此外，在经SNAP和SNP处理后，高尔基体堆叠的潴泡略有内卷，没有囊泡被 pinched off。NO清除剂cPTIO（2-（4-羧基苯基）-4,4,5,5-四甲基咪唑啉-1-氧基-3-氧化物，钾盐）消除了SNP的作用，从而证实细胞生长的抑制是由于一氧化氮。添加碘乙酸，一种含半胱氨酸酶（如甘油醛-3-磷酸脱氢酶（GAPDH））的抑制剂，对细胞生长和次生壁形成产生的影响与用NO供体处理所获得的相似。因此，我们推测NO通过对半胱氨酸残基进行S-亚硝基化来抑制参与分泌途径的酶（如GAPDH）的活性，从而调节齿状微星鼓藻的细胞生长。
