Light regulation of resistance to oxidative damage and magnetic crystal biogenesis in Magnetospirillum magneticum mediat
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APPLIED GENETICS AND MOLECULAR BIOTECHNOLOGY
Light regulation of resistance to oxidative damage and magnetic crystal biogenesis in Magnetospirillum magneticum mediated by a Cys-less LOV-like protein Haitao Chen 1,2,3 & Kefeng Li 1,4 & Yao Cai 5 & Pingping Wang 1,3 & Weimin Gong 6 & Long-Fei Wu 3,7 & Tao Song 1,2,3 Received: 16 April 2020 / Revised: 1 July 2020 / Accepted: 2 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Light–oxygen–voltage (LOV) proteins are ubiquitous photoreceptors that can interact with other regulatory proteins and then mediate their activities, which results in cellular adaptation and subsequent physiological changes. Upon blue-light irradiation, a conserved cysteine (Cys) residue in LOV covalently binds to flavin to form a flavin–Cys adduct, which triggers a subsequent cascade of signal transduction and reactions. We found a group of natural Cys-less LOV-like proteins in magnetotactic bacteria (MTB) and investigated its physiological functions by conducting research on one of these unusual LOV-like proteins, Amb2291, in Magnetospirillum magneticum. In-frame deletion of amb2291 or site-directive substitution of alanine-399 for Cys mutants impaired the protective responses against hydrogen peroxide, thereby causing stress and growth impairment. Consequently, gene expression and magnetosome formation were affected, which led to high sensitivity to oxidative damage and defective phototactic behaviour. The purified wild-type and A399C-mutated LOV-like proteins had similar LOV blue-light response spectra, but Amb2291A399C exhibited a faster reaction to blue light. We especially showed that LOV-like protein Amb2291 plays a role in magnetosome synthesis and resistance to oxidative stress of AMB-1 when this bacterium was exposed to red light and hydrogen peroxide. This finding expands our knowledge of the physiological function of this widely distributed group of photoreceptors and deepens our understanding of the photoresponse of MTB. Key Points • We found a group of Cys-less light–oxygen–voltage (LOV) photoreceptors in magnetotactic bacteria, which prompted us to study the light-response and biological roles of these proteins in these non-photosynthetic bacteria. • The Cys-less LOV-like protein participates in the light-regulated signalling pathway and improves resistance to oxidative damage and magnetic crystal biogenesis in Magnetospirillum magneticum. • This result will contribute to our understanding of the structural and functional diversity of the LOV-like photoreceptor and help us understand the complexity of light-regulated model organisms. Keywords LOV . Magnetotactic bacteria . Amb2291 . Oxidative stress . Reactive oxygen species
Introduction Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00253-020-10807-5) contains supplementary material, which is available to authorized users. * Long-Fei Wu [email protected] * Tao Song [email protected] Extended author information available on the last page of the ar
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