Why do alpha-cyanobacteria with form 1A RuBisCO dominate aquatic habitats worldwide? (CYANORUB)

为什么具有 1A 型 RuBisCO 的 α-蓝藻在全世界的水生栖息地中占主导地位？

• 批准号: EP/Y028384/1
• 负责人: David Scanlan
• 金额: $ 23.84万
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FY028384%2F1
• 关键词: Why; do; alpha; cyanobacteria; form

RuBisCO is one of the most abundant enzymes on Earth. Virtually all food webs depend on it to supply fixed carbon. In aerobicenvironments, RuBisCO struggles to distinguish efficiently between CO2 and O2. To compensate, many photosynthetic organismshave developed CO2-concentrating mechanisms (CCMs) to increase the [CO2] around the RuBisCO active site. In cyanobacteria,carboxysomes represent one such CCM, of which two independent forms exist: alpha and beta. This ancient photoautotrophiclineage has succeeded in colonizing habitats worldwide, being primary producers of great ecological importance. Amongst them,cells of the genera Prochlorococcus and Synechococcus, the two most abundant photosynthetic taxa on Earth, dominate oceanicecosystems. These marine picocyanobacteria possess a form IA RuBisCO and alpha-carboxysomes (so-called alpha-cyanobacteria).The remainder of the cyanobacterial radiation was thought to possess beta-carboxysomes and a form IB RuBisCO (beta-cyanobacteria), including freshwater unicellular and filamentous bloom-forming taxa comprising model organisms used inlaboratories worldwide e.g. Synechococcus elongatus and Synechocystis. However, recently I have isolated and sequenced thegenomes of many new unicellular freshwater picocyanobacteria that are phylogenetically much closer to their marine counterpartsand which also possess a form IA RuBisCO and alpha-carboxysomes. Moreover, these organisms have been detected in highabundance in freshwater lakes and reservoirs worldwide. Thus, alpha-cyanobacteria dominate all aquatic systems. CYANORUB seeksto address why this is the case. We hypothesize that alpha-cyanobacteria dominate large, temporally stable water masses,characterized by well-buffered pHs and relatively slow changes in carbonate chemistry. CYANORUB will be crucial for accuratelypredicting the biosphere's response to changing CO2, pH and carbonate chemistry and has biotechnological applications aimed atimproving plant growth.

RuBisCO 是地球上最丰富的酶之一。几乎所有食物网都依赖它来提供固定碳。在有氧环境中，RuBisCO 很难有效地区分 CO2 和 O2。为了补偿，许多光合生物已经开发出二氧化碳浓缩机制（CCM）来增加RuBisCO活性位点周围的[CO2]。在蓝细菌中，羧基体代表了一种这样的CCM，其中存在两种独立的形式：α和β。这种古老的光合自养谱系已成功地在世界各地的栖息地中定居，成为具有重要生态意义的初级生产者。其中，原绿球藻属和聚球藻属的细胞是地球上最丰富的两种光合类群，在海洋冰生态系统中占主导地位。这些海洋微微蓝藻具有IA型RuBisCO和α-羧基体（所谓的α-蓝藻）。其余的蓝藻辐射被认为具有β-羧基体和IB型RuBisCO（β-蓝藻），包括淡水单细胞和丝状蓝藻。水华形成类群，包括世界各地实验室使用的模式生物，例如细长聚球藻和集胞藻。然而，最近我分离并测序了许多新的单细胞淡水微微蓝细菌的基因组，这些细菌在系统发育上更接近于海洋细菌，并且还具有IA型RuBisCO和α-羧基体。此外，这些生物体在世界各地的淡水湖泊和水库中含量很高。因此，α-蓝藻在所有水生系统中占主导地位。 CYANORUB 试图解决出现这种情况的原因。我们假设α-蓝细菌主导着大型、暂时稳定的水团，其特点是pH缓冲良好，碳酸盐化学变化相对缓慢。 Cyanorub 对于准确预测生物圈对二氧化碳、pH 值和碳酸盐化学变化的反应至关重要，并且具有旨在改善植物生长的生物技术应用。