Serrano E E, Zeiger E, Hagiwara S
Department of Physiology, Ahmanson Laboratory of Neurobiology, Jerry Lewis Neuromuscular Research Center, Los Angeles, CA.
Proc Natl Acad Sci U S A. 1988 Jan;85(2):436-40. doi: 10.1073/pnas.85.2.436.
Stomatal opening in response to light has a component that matches the absorption spectrum of chlorophyll; however, the intervening sensory transduction steps are not well understood. To study this process, we illuminated Vicia faba guard cell protoplasts with red light and simultaneously recorded current flow across the plasma membrane, utilizing the patch clamp technique in the whole cell configuration. We report evidence that under voltage clamp conditions, red light (1 mmol of photons.m-2.S-1) stimulated an outward current. This response required ATP (2.5 mM) and orthophosphate (1 mM) at the cytoplasmic side of the membrane. Both red-light-stimulated currents and currents activated in the dark by the proton pump agonist fusicoccin (10 microM) were abolished by the protonophore carbonylcyanide m-chlorophenylhydrazone at 10 microM, indicating that these responses were carried by protons. Pump currents were inhibited by orthovanadate applied to the cytoplasmic side of the membrane (50% inhibition at 3.5 microM), implicating a H+ -ATPase. Elimination of the current by the photosynthetic inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea, in the presence of saturating concentrations of ATP, pointed to a requirement for photosynthetically active chloroplasts. We conclude that red light stimulates an electrogenic proton pump at the plasmalemma of Vicia guard cells and that chloroplasts modulate this response.
气孔对光作出反应而开放，其中有一个成分与叶绿素的吸收光谱相匹配；然而，其间的感觉转导步骤还不太清楚。为了研究这个过程，我们用红光照射蚕豆保卫细胞原生质体，并利用全细胞模式下的膜片钳技术同时记录跨质膜的电流。我们报告的证据表明，在电压钳制条件下，红光（1 mmol光子·m⁻²·s⁻¹）刺激了外向电流。这种反应在膜的细胞质一侧需要ATP（2.5 mM）和正磷酸盐（1 mM）。在10 μM的质子载体羰基氰化物间氯苯腙作用下，红光刺激的电流和在黑暗中由质子泵激动剂藤霉素（10 μM）激活的电流都被消除，这表明这些反应是由质子介导的。泵电流受到施加到膜细胞质一侧的原钒酸盐的抑制（在3.5 μM时50%抑制），这意味着存在一种H⁺-ATP酶。在存在饱和浓度ATP的情况下，光合抑制剂3-(3,4-二氯苯基)-1,1-二甲基脲消除了电流，这表明需要有光合活性的叶绿体。我们得出结论，红光刺激蚕豆保卫细胞质膜上的一个生电质子泵，并且叶绿体调节这种反应。
