FAD-sequestering proteins protect mycobacteria against hypoxic and oxidative stress.

Autor:	Harold LK; From the Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand.; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1042, New Zealand., Antoney J; Research School of Chemistry, The Australian National University, Canberra, Australia.; The Commonwealth Scientific and Industrial Research Organisation, Land and Water Flagship, Canberra, Australian Capital Territory, Australia, and., Ahmed FH; Research School of Chemistry, The Australian National University, Canberra, Australia.; The Commonwealth Scientific and Industrial Research Organisation, Land and Water Flagship, Canberra, Australian Capital Territory, Australia, and., Hards K; From the Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand., Carr PD; Research School of Chemistry, The Australian National University, Canberra, Australia., Rapson T; The Commonwealth Scientific and Industrial Research Organisation, Land and Water Flagship, Canberra, Australian Capital Territory, Australia, and., Greening C; The Commonwealth Scientific and Industrial Research Organisation, Land and Water Flagship, Canberra, Australian Capital Territory, Australia, and chris.greening@monash.edu.; School of Biological Sciences, Monash University, Melbourne, Australia., Jackson CJ; Research School of Chemistry, The Australian National University, Canberra, Australia, colin.jackson@anu.edu.au., Cook GM; From the Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand, greg.cook@otago.ac.nz.; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1042, New Zealand.
Jazyk:	angličtina
Zdroj:	The Journal of biological chemistry [J Biol Chem] 2019 Feb 22; Vol. 294 (8), pp. 2903-2912. Date of Electronic Publication: 2018 Dec 19.
DOI:	10.1074/jbc.RA118.006237
Abstrakt:	The ability to persist in the absence of growth triggered by low oxygen levels is a critical process for the survival of mycobacterial species in many environmental niches. MSMEG_5243 ( fsq ), a gene of unknown function in Mycobacterium smegmatis , is up-regulated in response to hypoxia and regulated by DosRDosS/DosT, an oxygen- and redox-sensing two-component system that is highly conserved in mycobacteria. In this communication, we demonstrate that MSMEG_5243 is a f lavin- seq uestering protein and henceforth refer to it as Fsq. Using an array of biochemical and structural analyses, we show that Fsq is a member of the diverse superfamily of flavin- and deazaflavin-dependent oxidoreductases (FDORs) and is widely distributed in mycobacterial species. We created a markerless deletion mutant of fsq and demonstrate that fsq is required for cell survival during hypoxia. Using fsq deletion and overexpression, we found that fsq enhances cellular resistance to hydrogen peroxide treatment. The X-ray crystal structure of Fsq, solved to 2.7 Å, revealed a homodimeric organization with FAD bound noncovalently. The Fsq structure also uncovered no potential substrate-binding cavities, as the FAD is fully enclosed, and electrochemical studies indicated that the Fsq:FAD complex is relatively inert and does not share common properties with electron-transfer proteins. Taken together, our results suggest that Fsq reduces the formation of reactive oxygen species (ROS) by sequestering free FAD during recovery from hypoxia, thereby protecting the cofactor from undergoing autoxidation to produce ROS. This finding represents a new paradigm in mycobacterial adaptation to hypoxia. (© 2019 Harold et al.)
Databáze:	MEDLINE
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