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Publication Abstract from PubMed

AIMS: Genetically encoded GFP-based redox biosensors are widely used to monitor specific and dynamic redox processes in living cells. Over the last years, various biosensors for a variety of applications were engineered and enhanced to match the organism and cellular environments, which should be investigated. In this context, the unicellular intraerythrocytic parasite Plasmodium, the causative agent of malaria, represents a challenge, as the small size of the organism results in weak fluorescence signals that complicate precise measurements, especially for cell compartment-specific observations. To address this, we have functionally and structurally characterized an enhanced redox biosensor superfolder roGFP2 (sfroGFP2). RESULTS: SfroGFP2 retains roGFP2-like behavior, yet with improved fluorescence intensity in cellulo. SfroGFP2-based redox biosensors are pH-insensitive in a physiological pH range and show midpoint potentials comparable to roGFP2-based redox biosensors. Using crystallography and rigidity theory, we identified the superfolding mutations as being responsible for improved structural stability of the biosensor in a redox-sensitive environment, thus explaining the improved fluorescence intensity in cellulo. INNOVATION: This work provides insight into the structure and function of GFP-based redox biosensors. It describes an improved redox biosensor (sfroGFP2) suitable for measuring oxidizing effects within small cells where applicability of other redox sensor variants is limited. CONCLUSION: Improved structural stability of sfroGFP2 gives rise to increased fluorescence intensity in cellulo. Fusion to hGrx1 provides the hitherto most suitable biosensor for measuring oxidizing effects in Plasmodium. This sensor is of major interest for studying glutathione redox changes in small cells, as well as subcellular compartments in general.

Structure and function of redox-sensitive superfolder green fluorescent protein variant.,Heimsch K, Gertzen CW, Schuh K, Nietzel T, Rahlfs S, Przyborski J, Gohlke H, Schwarzlander M, Becker K, Fritz-Wolf K Antioxid Redox Signal. 2022 Jan 24. doi: 10.1089/ars.2021.0234. PMID:35072524^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.