光合微藻和细菌之间的相互作用会影响双方的生理,以环境相关的方式影响每个伴侣的健康和生态轨迹。通过与产生维生素B12(钴胺素)的中华根瘤菌的相互作用,可以增强莱茵衣藻的耐热性。这里,我们使用无标记的定量蛋白质组学来揭示正常和高温下相互作用所改变的代谢网络。我们创造了一个场景,其中中华根瘤菌的生长需要衣藻提供的碳用于共培养,而衣藻在高温下的存活依赖于钴胺素和可能由中华根瘤菌产生的其他代谢物。差异丰度分析鉴定了在每个温度下与单种培养物相比,共培养物中每个伴侣产生的蛋白质。在高温下,在衣藻的存在下,参与中华根瘤菌生产钴胺素的蛋白质增加,而在衣藻中,钴胺素依赖性甲硫氨酸合酶和与甲基化反应相关的某些蛋白质增加.共培养和热胁迫强烈调节了两个伴侣以及各种转运蛋白的中心代谢,这些转运蛋白可以促进养分的交叉利用。共培养调节了双组分或单组分信号转导系统的各种组分的表达,转录激活因子/调节因子,或西格玛因子,这表明复杂的调节网络以温度依赖的方式调节相互作用。值得注意的是,热和一般应激反应和抗氧化蛋白在共培养物中上调,这表明,尽管有互惠的好处,但互动对每个伴侣来说都是固有的压力。我们的结果深入了解了共生所需的代谢权衡以及升高的温度如何调节代谢网络。
目的:光合微藻是水生生态系统的主要初级生产者,在全球碳循环中发挥着重要作用。几乎每一种藻类都与不同的微生物群落相关联,这些微生物群落相互影响,它们的代谢活动或存活。细菌产生的一种影响藻类的化学物质是维生素B12,一种用于多种代谢功能的酶辅因子。莱茵衣藻通过在高温下产生氨基酸甲硫氨酸而受益于由黑根瘤菌产生的维生素B12,这是衣藻耐热性所必需的。然而,在正常和压力温度下,我们对这种相互作用的理解很差。这里,我们使用定量蛋白质组学来鉴定差异表达的蛋白质,以揭示衣藻和中华根瘤菌所进行的代谢调节,这些调节可以促进这种共生.这些发现将增强我们对光合藻类及其相关微生物群如何随着全球温度升高而做出反应的理解。
Interactions between photosynthetic microalgae and bacteria impact the physiology of both partners, which influence the fitness and ecological trajectories of each partner in an environmental context-dependent manner. Thermal tolerance of Chlamydomonas reinhardtii can be enhanced through a mutualistic interaction with vitamin B12 (cobalamin)-producing Sinorhizobium meliloti. Here, we used label-free quantitative proteomics to reveal the metabolic networks altered by the interaction under normal and high temperatures. We created a scenario where the growth of Sinorhizobium requires carbon provided by Chlamydomonas for growth in co-cultures, and survival of Chlamydomonas under high temperatures relies on cobalamin and possibly other metabolites produced by Sinorhizobium. Differential abundance analysis identified proteins produced by each partner in co-cultures compared to mono-cultures at each temperature. Proteins involved in cobalamin production by Sinorhizobium increased in the presence of Chlamydomonas under elevated temperatures, whereas in Chlamydomonas, there was an increase in cobalamin-dependent methionine synthase and certain proteins associated with methylation reactions. Co-cultivation and heat stress strongly modulated the central metabolism of both partners as well as various transporters that could facilitate nutrient cross-utilization. Co-cultivation modulated expression of various components of two- or one-component signal transduction systems, transcriptional activators/regulators, or sigma factors, suggesting complex regulatory networks modulate the interaction in a temperature-dependent manner. Notably, heat and general stress-response and antioxidant proteins were upregulated in co-cultures, suggesting that the interaction is inherently stressful to each partner despite the benefits of mutualism. Our results shed insight into the metabolic tradeoffs required for mutualism and how metabolic networks are modulated by elevated temperature.
OBJECTIVE: Photosynthetic microalgae are key primary producers in aquatic ecosystems, playing an important role in the global carbon cycle. Nearly every alga lives in association with a diverse community of microorganisms that influence each other and their metabolic activities or survival. One chemical produced by bacteria that influence algae is vitamin B12, an enzyme cofactor used for a variety of metabolic functions. The alga Chlamydomonas reinhardtii benefits from vitamin B12 produced by Sinorhizobium meliloti by producing the amino acid methionine under high temperatures which are required for Chlamydomonas thermotolerance. Yet, our understanding of this interaction under normal and stressful temperatures is poor. Here, we used quantitative proteomics to identify differentially expressed proteins to reveal metabolic adjustments made by Chlamydomonas and Sinorhizobium that could facilitate this mutualism. These findings will enhance our understanding of how photosynthetic algae and their associated microbiomes will respond as global temperatures increase.