Investigating inorganic carbon transport in globally important algal lineages

藻类占全球光合作用总量的30%，光合作用是光和二氧化碳以糖的形式转化为O2和化学能的过程。这一过程为全球食物网的底层提供能源，产生我们呼吸的O2，并在从大气中消除温室气体二氧化碳方面发挥重要作用。藻类进化出了一种促进光合作用的机制，使其非常高效，这种机制被称为二氧化碳浓缩机制(CCM)。CCM通过从环境中吸收二氧化碳和HCO3-来促进光合作用。藻类吸收HCO3-以及必要的二氧化碳是因为：(1)它可以很容易地转化为光合作用所需的二氧化碳；(2)在藻类生存的水生环境中，它比二氧化碳更容易获得；(3)它不会像二氧化碳那样泄漏到细胞中。HCO3-通过藻细胞被运输到一个被称为类囊体的隔间，该隔间位于叶绿体中，是发生光合作用过程的地方。在类囊体中，HCO3-被转化为二氧化碳。然后，二氧化碳很容易被一种名为Rubisco的酶所利用，该酶利用二氧化碳来驱动光合作用过程。虽然我们知道HCO3-转运在CCM中非常重要，但到目前为止，我们还不知道它是如何进入类囊体转化为CO2的。我的研究最近在一种名为衣藻的藻类中发现了一种蛋白质通道，它能够将HCO3运输到类囊体内。我还在其他环境重要的藻类中发现了类似的蛋白质通道。我推测，这些相似的蛋白质通道可能是HCO3跨藻类运输的共同机制。我提议的联谊会研究将广泛调查不同藻类中这些潜在的HCO3-通道，以充分了解它们的功能。许多藻类都有CCM，但我们知道不同类群的具体机制是不同的。因此，重要的是在不同的组中探索CCM成分，如HCO3-通道，以便能够准确地向研究界提供关于藻类CCM中共享成分的信息。这项研究很重要，因为它加强了我们对这个过程的理解，这个过程大约占全球光合作用的三分之一，影响着地球上的所有生命。这个项目中产生的数据还有助于与我密切合作的研究人员，他们正试图将CCM改造成农作物。如果CCM被成功地植入作物中，它已经被模拟为显著提高光合作用效率，从而使作物产量增加高达60%。这种增产可以直接缓解因人口增加和气候变化而不断增加的全球粮食供应问题。

Algae are responsible for up to 30% of all global photosynthesis, the process whereby light and CO2 are converted into O2 and chemical energy, in the form of sugars. This process provides energy for the bottom of the global food web, produces the O2 we breathe and plays an important role in removing the greenhouse gas CO2 from the atmosphere. Algae have evolved a mechanism to boost their photosynthesis making it very efficient, this mechanism is known as the CO2 concentrating mechanism (CCM). The CCM functions by taking up both CO2 and HCO3- from the environment to fuel photosynthesis. Algae take up HCO3- as well as the necessary CO2 because: (1) it can easily be converted to the CO2 needed for photosynthesis; (2) it is more readily available than CO2 in the aquatic environments algae live in; and (3) it doesn't leak out the cell like CO2 is prone to. The HCO3- is transported through the algal cell to a compartment called the thylakoid, which is found in the chloroplast and is where the photosynthetic process occurs. In the thylakoid the HCO3- is converted to CO2. The CO2 then is readily available for an enzyme called Rubisco which uses it to drive the photosynthesis process. Although we know HCO3- transport is very important in the CCM, until now we did not know how it travelled into the thylakoid to be converted to CO2. My research has recently identified a protein channel that enables HCO3- transport into the thylakoid in a species of algae called Chlamydomonas reinhardtii. I have also identified similar protein channels in other environmentally important groups of algae. I hypothesise that these similar protein channels may be a shared mechanism of HCO3- transport across algal groups. The Fellowship research I have proposed will extensively investigate these potential HCO3- channels in different algal groups to fully understand their function. Many algae have a CCM, but we know there are differences in the specific mechanism between different groups. Therefore, it is important to explore CCM components, like HCO3- channels, in different groups to be able to inform the research community accurately on the shared components in the algal CCM. This research is important because it strengthens our understanding of a process responsible for approximately a third of all global photosynthesis, influencing all life on Earth. The data generated in this project also helps researchers I collaborate with closely who are attempting to engineer a CCM into crop plants. If the CCM is successfully inserted into crop plants, it has been modelled to significantly increase photosynthetic efficiency and therefore increase crop yields by up to 60%. This yield increase could directly alleviate issues surrounding global food supply which have been increasing as a result of population increase and climate change.