A new widespread subclass of carbonic anhydrase in marine phytoplankton
A new widespread subclass of carbonic anhydrase in marine phytoplankton
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DOI：
10.1038/s41396-019-0426-8
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发表时间：
2019-08-01
期刊：
影响因子：
11
通讯作者：
Gontero, Brigitte
中科院分区：
文献类型：
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作者：
Jensen, Erik L.;Clement, Romain;Gontero, Brigitte
大多数水生光自养生物依靠二氧化碳浓缩机制（CCMs）来维持环境CO2浓度下的生产力，而碳酸酐酶（CA）在这些过程中起着关键作用。在这里，我们提出了不同的证据线，表明在海洋硅藻thalassisira pseudonana中发现的蛋白质LCIP63是一个CA。然而，序列分析表明它与任何已知的CA具有较低的一致性，因此属于一个新的亚类，我们将其命名为iota-CA。此外，LCIP63异常倾向于Mn2+而不是Zn2+作为辅因子，这可能具有潜在的生态相关性，因为海洋中Mn2+比Zn2+更丰富。LCIP63位于叶绿体中，仅在低浓度CO2下表达。当使用生物转化过度表达时，在溶解无机碳的限制浓度下，光合作用速率增加，证实了其在CCM中的作用。LCIP63同源物存在于其他五种已测序的硅藻和其他藻类、细菌和古细菌中。因此，LCIP63在系统发育上广泛存在，但被忽视。Tara海洋数据库的分析证实了这一点，并表明LCIP63在海洋环境中广泛分布，因此可能在全球生物地球化学碳循环中发挥重要作用。
Most aquatic photoautotrophs depend on CO2-concentrating mechanisms (CCMs) to maintain productivity at ambient concentrations of CO2, and carbonic anhydrase (CA) plays a key role in these processes. Here we present different lines of evidence showing that the protein LCIP63, identified in the marine diatom Thalassiosira pseudonana, is a CA. However, sequence analysis showed that it has a low identity with any known CA and therefore belongs to a new subclass that we designate as iota-CA. Moreover, LCIP63 unusually prefers Mn2+ to Zn2+ as a cofactor, which is potentially of ecological relevance since Mn2+ is more abundant than Zn2+ in the ocean. LCIP63 is located in the chloroplast and only expressed at low concentrations of CO2. When overexpressed using biolistic transformation, the rate of photosynthesis at limiting concentrations of dissolved inorganic carbon increased, confirming its role in the CCM. LCIP63 homologs are present in the five other sequenced diatoms and in other algae, bacteria, and archaea. Thus LCIP63 is phylogenetically widespread but overlooked. Analysis of the Tara Oceans database confirmed this and showed that LCIP63 is widely distributed in marine environments and is therefore likely to play an important role in global biogeochemical carbon cycling.