The Biogenesis Structure and Function of Biological Membranes

地球上几乎所有的生命都从植物或生活在海洋、湖泊和池塘中的更简单的细菌光合生物那里获得所需的食物和氧气，从而支撑了所有的全球食物链。因为地球基本上是水生的，这些光合细菌的数量和活动是惊人的；每年有数十亿吨光合细菌在海洋中生长。这支看不见的微生物大军栖息在每一片海洋中，甚至生长在海面以下100米的地方。尽管对我们来说，这是漆黑的深渊，光合细菌却能茁壮成长，因为它们制造了大量的叶绿素，可以抓住每一个射向它们的光子。不起眼的光合细菌是主要食物链的起点，它们使海洋中的其他生命成为可能，也为我们中的许多人提供了食物。地球上有如此多的叶绿素，它的重量比人类的重量还重，然而，尽管它无处不在，对所有生命都很重要，令人惊讶的是，没有人完全了解叶绿素是如何形成的。更重要的是，在每个光合细胞中都有数百万个叶绿素分子，它们必须附着在蛋白质上，才能收集和利用来自太阳的能量，但是，尽管它至关重要，但没有人对这种附着过程一无所知。我们想知道细胞内的叶绿素和蛋白质是如何形成的，以及它们是如何组合在一起捕捉光线并将其转化为三磷酸腺苷（ATP）的，而三磷酸腺苷为数千种化学反应提供动力，使细胞能够生长和分裂。这些知识对我们所有人都很重要，不仅因为捕获和利用太阳能为生命提供燃料，而且它还掌握着设计和制造设备的秘密，这些设备有朝一日可以为我们提供清洁、无限的太阳能。我们如何获得这些知识？我们使用光合细菌，这种细菌在实验室工作台上发光的瓶子里快速而容易地生长，然后我们打开细菌，取出叶绿素蛋白质，看看它们是如何工作的。捕获太阳能的叶绿素蛋白质被称为光收集复合物（lhc）。就像卫星天线将微弱的电视信号集中到接收器上一样，数千个大型强子对撞机并排排列，收集太阳能并将其传送到少数几个反应中心（RC）。RC蛋白将lhc收集的能量转化为电能，在膜的两侧以正电荷和负电荷的形式存在，就像给生物电池充电一样；这推动了ATP的产生，ATP是所有细胞的化学燃料。我们想知道细胞是如何制造这些膜的，它们的效率如此之高，以至于99%的能量都被传递给了RC。为了获得如此高效的能量收集，我们知道lhc必须在膜中彼此紧密接触，但我们不知道细胞是如何做到这一点的。为了理解这种光合膜是如何工作的，我们必须遵循导致细胞内功能光收集网络的事件顺序。为了做到这一点，我们将使用原子力显微镜来“感觉”每个LHC和RC的形状，因为细胞将它们组成网络，并将这些信息转化为膜中所有东西的“照片”。通过重复拍摄膜在不同发育阶段的照片，我们可以看到大自然是如何实现这一生物工程壮举的。我们将如何运用这些知识？我们都需要电力，我们希望通过组装我们自己的人工光收集系统，并遵循能量如何被lhc捕获，然后输送到RC，从而开始从大自然中吸取教训。我们能有效地引导这些能量吗？我们能否将人工光收集系统直接“插入”光伏电池中来发电？通过汇集来自生物学、物理学和化学的科学家团队，我们将在研究中探索这些令人兴奋的可能性。

Nearly all life on Earth gets the food and oxygen it needs from plants, or from simpler bacterial photosynthetic organisms that live in oceans, lakes and ponds, thus underpinning all global food chains. Because the planet Earth is largely aquatic the quantity and activity of these photosynthetic bacteria is stupendous; billions of tonnes of photosynthetic bacteria grow in the oceans every year. This unseen microbial army inhabits every sea, even growing 100 metres below the surface. Although to us these are inky depths, photosynthetic bacteria can grow and thrive because they make so much chlorophyll that they can grab hold of every photon of light that comes their way. The humble photosynthetic bacteria are the start of the major food chains that make other life in the sea possible and so feed many of us too. There is so much chlorophyll on Earth that it weighs more than all of humankind, yet despite its omnipresence and its importance to all life, astonishingly, nobody understands fully how chlorophyll is made. What is more there are millions of chlorophyll molecules inside each photosynthetic cell, which have to be attached to proteins before they collect and use energy from the sun, but again despite its crucial importance, nobody understands anything about this attachment process. We want to find out how the chlorophylls and proteins inside cells are made, and how they are put together to capture light and convert it into ATP, which powers the thousands of chemical reactions that enable the cells to grow and divide. This knowledge is important to us all, not just because capturing and using solar energy fuels life, but it also holds the secret of designing and making devices that one day could give us clean, unlimited energy from sunlight. How can we gain this knowledge? We use photosynthetic bacteria, quick and easy to grow in illuminated bottles on a laboratory benchtop, and we then open up the bacteria, take out the chlorophyll-proteins and see how they work. The chlorophyll-proteins that capture solar energy are called light-harvesting complexes (LHCs). In much the same way as a satellite dish concentrates the weak TV signal onto the receiver, thousands of LHCs are grouped side-by-side to collect solar energy and deliver it to a small number of reaction centres (RC). The RC protein converts the energy harvested by the LHCs to electrical energy, in the form of positive and negative charges on either side of a membrane, like charging up a biological battery; this drives the production of ATP, the chemical fuels for all cells. We want to know how the cell makes these membranes, so amazingly efficient that 99% of the energy that falls on them is delivered to the RC. To get such highly efficient energy collection we know that LHCs must be packed in close contact with one another in the membrane but we do not know how the cell manages to do this. To understand how such a photosynthetic membrane works we must follow the sequence of events that leads to the functional light harvesting network inside the cells. To do this we will use an atomic force microscope to literally 'feel' the shapes of each LHC and RC as the cell makes networks of them and turn this information into a 'photograph' of where everything is in the membrane. By taking repeated pictures of membranes at different stages in their development we can see how nature achieves this feat of bio-engineering. How will we use this knowledge? We all need electricity and we want to make a start on learning lessons from nature by assembling our own artificial light harvesting system and following how the energy is captured by LHCs then channeled to a RC. Can we channel this energy efficiently? Can we 'plug' our artificial light harvesting system directly into a photovoltaic cell to make electricity? By bringing together a team of scientists from Biology, Physics and Chemistry we will explore these exciting possibilities in our research.