Extracellular carbonic anhydrase facilitates carbon dioxide availability for photosynthesis in the marine dinoflagellate Prorocentrum micans
Extracellular carbonic anhydrase facilitates carbon dioxide availability for photosynthesis in the marine dinoflagellate Prorocentrum micans
复制标题
DOI：
10.1104/pp.120.1.105
复制
发表时间：
1999-05-01
期刊：
影响因子：
7.4
通讯作者：
Merrett, MJ
中科院分区：
文献类型：
--
作者：
Nimer, NA;Brownlee, C;Merrett, MJ
研究了海洋甲藻海洋原甲藻光合作用与无机碳积累的关系。内部无机碳池的测量表明，10倍的积累，相对于外部溶解无机碳（DIC）。葡聚糖结合的磺酰胺（DBS），抑制细胞外碳酸酐酶，导致超过95%的DIC积累和光合作用的抑制。我们使用实时成像的活细胞与共聚焦激光扫描显微镜和荧光pH指示剂染料来测量瞬时pH值的变化与无机碳的可用性。当稳态光合细胞DIC限制，叶绿体pH值从8.3下降到6.9和胞质pH值从7.7下降到7.1。重新加入HCO 3-导致DBS废除的稳态pH值的快速重建。在稳态条件下向光合作用细胞中添加DBS导致细胞内pH值的瞬时增加，光合作用维持6 s，这是细胞内无机碳库耗尽所需的时间量。这些结果表明，细胞外碳酸酐酶的关键作用，在促进CO的可用性，在外表面的质膜必要的维持光合速率。在环境CO2浓度的CO2浓缩机制的需要可能反映了核酮糖-1，5二磷酸羧化酶/加氧酶的特异性因子的差异，甲藻与其他藻类门相比。
This study investigated inorganic carbon accumulation in relation to photosynthesis in the marine dinoflagellate Prorocentrum micans. Measurement of the internal inorganic carbon pool showed a 10-fold accumulation in relation to external dissolved inorganic carbon (DIC). Dextran-bound sulfonamide (DBS), which inhibited extracellular carbonic anhydrase, caused more than 95% inhibition of DIC accumulation and photosynthesis. We used real-time imaging of living cells with confocal laser scanning microscopy and a fluorescent pH indicator dye to measure transient pH changes in relation to inorganic carbon availability. When steady-state photosynthesizing cells were DIC limited, the chloroplast pH decreased from 8.3 to 6.9 and cytosolic pH decreased from 7.7 to 7.1. Readdition of HCO3- led to a rapid re-establishment of the steady-state pH values abolished by DBS. The addition of DBS to photosynthesizing cells under steady-state conditions resulted in a transient increase in intracellular pH, with photosynthesis maintained for 6 s, the amount of time needed for depletion of the intracellular inorganic carbon pool. These results demonstrate the key role of extracellular carbonic anhydrase in facilitating the availability of CO, at the exofacial surface of the plasma membrane necessary to maintain the photosynthetic rate. The need for a CO2-concentrating mechanism at ambient CO2 concentrations may reflect the difference in the specificity factor of ribulose-1,5 bisphosphate carboxylase/oxygenase in dinoflagellates compared with other algal phyla.