Department of Botany, Iowa State University, Ames, Iowa 50011.
Plant Physiol. 1991 Sep;97(1):420-5. doi: 10.1104/pp.97.1.420.
The activity of two photorespiratory enzymes, phosphoglycolate phosphatase (PGPase) and glycolate dehydrogenase (glycolate DH), changes when CO(2)-enriched wild-type (WT) Chlamydomonas reinhardtii cells are transferred to air levels of CO(2). Adaptation to air levels of CO(2) by Chlamydomonas involves induction of a CO(2)-concentrating mechanism (CCM) which increases the internal inorganic carbon concentration and suppresses oxygenase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase. PGPase in cell extracts shows a transient increase in activity that reaches a maximum 3 to 5 hours after transfer and then declines to the original level within 48 hours. The decline in PGPase activity begins at about the time that physiological evidence indicates the CCM is approaching maximal activity. Glycolate DH activity in 24 hour air-adapted WT cells is double that seen in CO(2)-enriched cells. Unlike WT, the high-CO(2)-requiring mutant, cia-5, does not respond to limiting CO(2) conditions: it does not induce any known aspects of the CCM and it does not show changes in PGPase or glycolate DH activities. Other known mutants of the CCM show patterns of PGPase and glycolate DH activity after transfer to limiting CO(2) which are different from WT and cia-5 but which are consistent with changes in activity being initiated by the same factor that induces the CCM, although secondary regulation must also be involved.
当富含 CO2 的野生型（WT）衣藻细胞转移到空气中 CO2 水平时，两种光呼吸酶，磷酸甘油酸磷酸酶（PGPase）和乙醇酸脱氢酶（glycolate DH）的活性会发生变化。衣藻适应空气中的 CO2 水平涉及诱导 CO2 浓缩机制（CCM），这会增加内部无机碳浓度并抑制核酮糖-1,5-二磷酸羧化酶/加氧酶的加氧酶活性。细胞提取物中的 PGPase 活性会短暂增加，在转移后 3 到 5 小时达到最大值，然后在 48 小时内降至原始水平。PGPase 活性的下降始于生理证据表明 CCM 接近最大活性的时间。24 小时空气适应的 WT 细胞中的乙醇酸 DH 活性是 CO2 富集细胞中的两倍。与 WT 不同，高 CO2 需求突变体 cia-5 不会对限制 CO2 条件做出反应：它不会诱导 CCM 的任何已知方面，也不会显示 PGPase 或乙醇酸 DH 活性的变化。CCM 的其他已知突变体在转移到限制 CO2 后，PGPase 和乙醇酸 DH 活性的模式与 WT 和 cia-5 不同，但与由诱导 CCM 的相同因素引发的活性变化一致，尽管二次调节也必须参与。
