Origin of cyanobacterial thylakoids via a non-vesicular glycolipid phase transition and their impact on the Great Oxygenation Event

Abstract

Appearance of oxygenic photosynthesis in Cyanobacteria is a major event in the evolution of Life. It had an irreversible impact on our planet, promoting the Great Oxygenation Event (GOE), ~2.4 b.y.a. Ancient Cyanobacteria predating the GOE were Gloeobacter-type cells, having no thylakoids. They hosted photosystems in their cytoplasmic membrane. The driver of the GOE was proposed to be the transition from unicellular to filamentous Cyanobacteria. However, the appearance of thylakoids expanded the photosynthetic surface by multiple logs: this multiplier effect would be more coherent with an impact on the atmosphere. Primitive thylakoids self-organize as concentric parietal uninterrupted multilayers. The quest for their origin resists vesicular-based scenarios. This review reports studies supporting that Hexagonal II-forming gluco- and galactolipids at the periphery of the cytosolic membrane could be turned within nanoseconds and without any external source of energy into membrane multilayers. Comparison of lipid biosynthetic pathways further shows that ancient Cyanobacteria contained only one anionic Lamellar-forming lipid, phosphatidylglycerol. Acquisition of sulfoquinovosyldiacylglycerol biosynthesis correlates with thylakoid emergence, possibly enabling a sufficient provision of anionic lipids to trigger an Hexagonal II-to-Lamellar phase transition. With this non-vesicular lipid-phase transition, a framework is also available to reexamine the role of companion proteins in thylakoid biogenesis processes.

Microbial‐Enabled Photosynthetic Oxygenation for Disease Treatment

“…[141] Ultrasound is utilized in SDT to activate the aggregated sonosensitizer within the tumor, converting it to an activated state. The activated sensitizer converts the surrounding molecular oxygen into ROS dominated by 1 O 2 through energy transfer, which kills tumor cells with the synergy of ultrasound. [142] Ultrasound has superior penetrability, focusability, and selectivity of the irradiation site compared to the light used in PDT.…”

“…In vitro S-UCNP can not only increase oxygen production by increasing Syn7942 concentration, but also can continuously produce oxygen under cyclic light to relieve hypoxia of tumor cells and reduce HIF-1𝛼 expression. Moreover, Syn7942 could continue to proliferate in high-concentration 1 O 2 and high-temperature environment. While in a hypoxic environment, S-UCNP-Ce6 could generate a large amount of ROS under 980 nm laser irradiation compared to PDT of UCNP-Ce6 alone, indicating that the photosynthetic oxygen production of cyanobacteria under laser irradiation can significantly enhance the 1 O 2 generation of Ce6.…”

“…2.4 billion years ago, cyanobacteria introduced oxygen, a colorless and odorless gas, to the earth through photosynthesis, and since then, the evolution of various organisms in nature is closely intertwined with oxygen. [ 1 ] Oxygen is crucial for human life as it plays a significant role in cell metabolism, [ 2 ] brain activity, [ 3 ] and heart function, [ 4 ] serving as an essential energy source. [ 5 ] Thus, human life is inextricably in need of oxygen, and lack of oxygen, or hypoxia, can pose a significant risk to human health.…”