A biological function for cadmium in marine diatoms
A biological function for cadmium in marine diatoms
复制标题
DOI：
10.1073/pnas.090091397
复制
发表时间：
2000-04-25
影响因子：
11.1
通讯作者：
Morel, FMM
中科院分区：
文献类型：
--
作者：
Lane, TW;Morel, FMM
镉在海洋中的分布与磷酸盐等主要藻类营养物质的分布密切相关。然而，这种“营养素样”分布的原因尚不清楚，因为镉通常不被认为具有生物学功能。在此，我们提供的证据表明，镉在海洋硅藻海链藻weissflorescent低锌的条件下，典型的海洋环境中的生物作用。在锌限制培养物中加入镉可提高T. weissfloprotein，特别是在低pCO（2）。这种生长速率的增加反映在细胞碳酸酐酶（CA）活性水平的增加上，尽管T. Weissflocker保持低姿态Cd-109标记与显示CA活性的蛋白条带共迁移，并且在放射性标记的T的非变性PAGE上不同于TWCA 1。weissflorescent细胞裂解物。Cd蛋白的水平由CO2以与这种酶在碳获取中的作用一致的方式调制。CA活性组分的纯化导致43 kDa的含Cd蛋白的分离。现在很清楚T. weissfloprotein表达的镉特异性CA，特别是在锌限制的条件下，可以取代锌酶TWCA 1在其碳浓缩机制。
The oceanic distribution of cadmium follows closely that of major algal nutrients such as phosphate. The reasons for this "nutrient-like" distribution are unclear, however, because cadmium is not generally believed to have a biological function. Herein, we provide evidence of a biological role for Cd in the marine diatom Thalassiosira weissflogii under conditions of low zinc, typical of the marine environment. Addition of Cd to Zn-limited cultures enhances the growth rate of T. weissflogii, particularly at low pCO(2). This increase in growth rate is reflected in increased levels of cellular carbonic anhydrase (CA) activity, although the levels of TWCA1, the major intracellular Zn-requiring isoform of CA in T. weissflogii, remain low. Cd-109 label comigrates with a protein band that shows CA activity and is distinct from TWCA1 on native PAGE of radiolabeled T. weissflogii cell lysates. The levels of the Cd protein are modulated by CO2 in a manner that is consistent with a role for this enzyme in carbon acquisition. Purification of the CA-active fraction leads to the isolation of a Cd-containing protein of 43 kDa. It is now clear that T. weissflogii expresses a Cd-specific CA, which, particularly under conditions of Zn limitation, can replace the Zn enzyme TWCA1 in its carbon-concentrating mechanism.