Oxygen triggers signal transduction in the DevS (DosS) sensor of Mycobacterium tuberculosis by modulating the quaternary structure

Abstract

A major challenge to the control and eventual eradication of Mycobacterium tuberculosis infection is this pathogen's prolonged dormancy. The heme‐based oxygen sensor protein DevS (DosS) plays a key role in this phenomenon, because it is a major activator of the transcription factor DevR. When DevS is active, its histidine protein kinase region is ON and it phosphorylates and activates DevR, which can induce the transcription of the dormancy regulon genes. Here, we have investigated the mechanism by which the ligation of molecular oxygen to a heme‐binding domain in DevS switches OFF its histidine protein kinase region. To shed light on the oligomerization states of this protein and possible protein‐surfaces of interaction, we used analytical gel filtration, together with dynamic light scattering, fluorescence spectroscopy and chemical crosslinking. We found that DevS exists as three major species: an octamer, a tetramer and a dimer. These three states were observed for the concentration range between 0.5 and 20 μm DevS, but not below 0.1 μm. Levels of DevS in M. tuberculosis are expected to range from 5 to 26 μm. When this histidine protein kinase was OFF, the DevS was mainly tetrameric and dimeric; by contrast, when the kinase was ON, the protein was predominantly octameric. The changes in quaternary structure were rapid upon binding to the physiological signal. This finding represents a novel strategy for switching the activity of a two‐component heme‐based sensor. An enhanced understanding of this process might potentially lead to the design of novel regulatory agents that target the multimer interfaces for treatment of latent tuberculosis.

A spectroelectrochemical investigation of the heme‐based sensor DevS from Mycobacterium tuberculosis: a redox versus oxygen sensor

“…These studies provide support for the actual responses to the ligands on the HD in a context of a full-length protein, which has showed to be quite distinct [36]. Indeed, more recently, we showed, depending on the ligand bound to DevS, oligomerization can be altered, where octamers are mainly found in the active states while tetramers and dimers in the inactive states [40]. Despite these major changes, our electrochemistry results did not provide any clear disturbance on the measurements.…”

“…) present structural evidence that might explain the differences in the redox behaviors of such proteins regarding ligand binding. Unfortunately, there is not much study on the full‐length conformational changes associated with signal transduction for DevS or DevS/DevR , whereas only one detailed structural study for full‐length FixL has been published .…”

The PolS-PolR Two-Component System Regulates Genes Involved in Poly-P Metabolism and Phosphate Transport in Microlunatus phosphovorus

“…There are three ppk genes encoding PPK in the NM-1 strain, and these genes are responsible for the synthesis of poly-P from ATP (He and McMahon, 2011; Kawakoshi et al, 2012). According to our results with RT-qPCR (Lobao et al, 2019), genes related to the biosynthesis of poly-P, including ppk (MLP_RS23025) and ppk2 (MLP_RS24205), were significantly down-regulated under anaerobic conditions, while the transcription level of ppk2 (MLP_RS02760) showed no obvious changes under aerobic or anaerobic conditions (Figure 4B). PPNK (MLP_RS08475), PAP (MLP_RS11265), PPX (MLP_RS21635), and PPGK (MLP_RS02595, MLP_RS12905) are the enzymes that catalyze poly-P into NADP, ADP, Pi and glucose-6-phosphate, respectively (He and McMahon, 2011; Kawakoshi et al, 2012).…”

“…Although the metabolism of poly-P differed in NM-1 under aerobic and anaerobic conditions, the genes regulating the response to the changing levels of dissolved oxygen remained largely uncharacterized. In Mycobacterium tuberculosis , the DevS-DevR TCS responds to oxygen levels, with the GAF domain of the HK DevS sensing oxygen signals, and following phosphorylation by DevS, the RR DevR regulates the expression of dormancy-related genes (Madrona et al, 2016; Lobao et al, 2019). We speculated that a TCS might mediate the transition response to changing oxygen levels in M. phosphovorus , and bioinformatics analysis indicated that its genome (NC_015635.1) contained three genes encoding proteins with GAF-like domains: MLP_RS09510, MLP_RS09650, and MLP_RS10500 (Figure 2).…”

“…In M. tuberculosis , the HK DevS/DosT are activated when the GAF domain senses hypoxia signals or oxygen, resulting in phosphorylation of DevR, which then binds to the promoters of the dormancy regulon and positively regulates the transcription of the associated genes. On the other hand, although GAF domains of DevS and DosT share 75% amino-acid sequence identity, they sense different signals (Kumar et al, 2007; Kaur et al, 2016; Lobao et al, 2019). Moreover, protein All4978 from Cyanobacterium Nostoc sp.…”