Schueler, D. | Search bioRxiv

bioRxiv2023

Exploring the host range for genetic transfer of magnetic organelle biosynthesis

Magnetosomes produced by magnetotactic bacteria have great potential for application in biotechnology and medicine due to their unique physicochemical properties and high biocompatibility. Recent studies uncovered the genetic determinants for magnetosome formation and inspired ideas to transfer the pathway into hitherto non-magnetic organisms. However, previous efforts to genetically magnetize other species have been successful in only a few bacterial recipients, revealing significant challenges in this approach. Here, by systematic examination of 25 proteobacterial hosts, we generated 7 novel magnetosome-producing strains. We further characterized the recombinant magnetosomes produced by these strains and delineate a set of auxiliary factors linked to magnetosome formation. Our findings will have significant implications for generation of magnetized life cells and the potential to facilitate the production of biogenic magnetic nanoparticles for a wide range of biomedical applications.

synthetic biology↗

bioRxiv2022

Hidden Talents: Silent Gene Clusters Encoding Magnetic Organelle Biosynthesis in a Non-Magnetotactic Phototrophic Bacterium

Horizontal gene transfer is a powerful source of innovations in prokaryotes that can affect almost any cellular system, including microbial organelles. However, typically rapid loss of non-functional gene acquisitions obscures the mechanisms determining the fate of horizontally transferable genes. Here, we report the first discovery of a horizontally inherited gene cluster encoding biosynthesis of magnetosomes, the organelles used by magnetotactic bacteria for navigation, in a non-magnetotactic phototrophic bacterium Rhodovastum atsumiense. We show that these clusters were inactivated through transcriptional silencing and antisense RNA regulation, but retain functionality, as several genes were able to complement the orthologous deletions in a remotely related magnetotactic bacterium. The laboratory transfer of foreign magnetosome genes to R. atsumiense was found to endow the strain with magnetosome biosynthesis, but strong negative selection led to rapid loss of this trait upon subcultivation. Our results provide insight into the horizontal dissemination of gene clusters encoding complex prokaryotic organelles and illuminate the potential mechanisms of their genomic preservation in a dormant state.

microbiology↗