Essential magnetosome proteins MamI and MamL from magnetotactic bacteria interact in mammalian cells

• Published in: Scientific reports Vol. 14; no. 1; pp. 26292 - 16
• Main Authors: Sun, Qin, Yu, Liu, Donnelly, Sarah C., Fradin, Cécile, Thompson, R. Terry, Prato, Frank S., Goldhawk, Donna E.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 631/337; 631/57; 631/80; 639/925; Biosensor; Cell fusion; Confocal microscopy; Fluorescence; Fluorescence spectroscopy; Fusion protein; Gene-based contrast; Green fluorescent protein; Humanities and Social Sciences; Immunoprecipitation; Intracellular; Localization; Magnetosome; Mammalian cells; Mammals; Microparticles; Molecular imaging; multidisciplinary; Nanoparticles; Nanotechnology; Protein interaction; Protein structure; Proteins; Science; Science (multidisciplinary); Tomatoes; Molecular imaging; Magnetic resonance imaging; Gene-based contrast; Biosensor; Magnetosome; Microparticles; Nanotechnology; Fluorescence correlation spectroscopy
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-024-77591-4

To detect cellular activities deep within the body using magnetic resonance platforms, magnetosomes are the ideal model of genetically-encoded nanoparticles. These membrane-bound iron biominerals produced by magnetotactic bacteria are highly regulated by approximately 30 genes; however, the number of magnetosome genes that are essential and/or constitute the root structure upon which biominerals form is largely undefined. To examine the possibility that key magnetosome genes may interact in a foreign environment, we expressed mamI and mamL as fluorescent fusion proteins in mammalian cells. Localization and potential protein-protein interaction(s) were investigated using confocal microscopy and fluorescence correlation spectroscopy (FCS). Enhanced green fluorescent protein (EGFP)-MamI and the red fluorescent Tomato-MamL displayed distinct intracellular localization, with net-like and punctate fluorescence, respectively. Remarkably, co-expression revealed co-localization of both fluorescent fusion proteins in the same punctate pattern. An interaction between MamI and MamL was confirmed by co-immunoprecipitation. In addition, changes in EGFP-MamI distribution were accompanied by acquisition of intracellular mobility which all Tomato-MamL structures displayed. Analysis of extracts from these cells by FCS was consistent with an interaction between fluorescent fusion proteins, including an increase in particle radius. Co-localization and interaction of MamI and MamL demonstrate that select magnetosome proteins may associate in mammalian cells.