Myoglobin-like aerotaxis transducers in Archaea and Bacteria

Hou, Shaobin; Larsen, Randy W.; Boudko, Dmitri Y.; Riley, Charles W.; Karatan, Ece; Zimmer, Mike; Ordal, George; Alam, Maqsudul

doi:10.1038/35000570

Cited by 261 publications

(273 citation statements)

References 25 publications

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“…To obtain better insight into the molecular mechanism of how DosS and DosT assist Mtb to enter latency, we sought to identify the physiologically relevant host ligands capable of reacting with these sensor kinases. It is well known that heme-binding sensors such as NifL (21), HemAT (22), and EcDOS (15) are capable of directly sensing O 2 through their heme prosthetic groups. We were particularly interested in NO and hypoxia, primarily because several lines of in vitro and in vivo evidence suggest that host-generated NO and hypoxia are associated with the establishment and maintenance of latent TB.…”

Section: Discussionmentioning

confidence: 99%

Mycobacterium tuberculosis DosS is a redox sensor and DosT is a hypoxia sensor

Kumar¹,

Toledo

Patel

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

294

368

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A fundamental challenge to the study of oxidative stress responses of Mycobacterium tuberculosis (Mtb) is to understand how the protective host molecules are sensed and relayed to control bacilli gene expression. The genetic response of Mtb to hypoxia and NO is controlled by the sensor kinases DosS and DosT and the response regulator DosR through activation of the dormancy/NO (Dos) regulon. However, the regulatory ligands of DosS and DosT and the mechanism of signal sensing were unknown. Here, we show that both DosS and DosT bind heme as a prosthetic group and that DosS is rapidly autooxidized to attain the met (Fe 3؉ ) form, whereas DosT exists in the O 2-bound (oxy) form. EPR and UV-visible spectroscopy analysis showed that O 2, NO, and CO are ligands of DosS and DosT. Importantly, we demonstrate that the oxidation or ligation state of the heme iron modulates DosS and DosT autokinase activity and that ferrous DosS, and deoxy DosT, show significantly increased autokinase activity compared with met DosS and oxy DosT. Our data provide direct proof that DosS functions as a redox sensor, whereas DosT functions as a hypoxia sensor, and that O 2, NO, and CO are modulatory ligands of DosS and DosT. Finally, we identified a third potential dormancy signal, CO, that induces the Mtb Dos regulon. We conclude that Mtb has evolved finely tuned redox and hypoxia-mediated sensing strategies for detecting O 2, NO, and CO. Data presented here establish a paradigm for understanding the mechanism of bacilli persistence.carbon monoxide ͉ dormancy ͉ nitric oxide ͉ oxygen ͉ persistence T uberculosis (TB) is a major global health burden, and current estimates suggest that one-third of the world's population (Ϸ2 billion) is latently infected with TB (1). Latency is important largely because persistent Mycobacterium tuberculosis (Mtb) are in a state of ''drug unresponsiveness'' wherein the bacilli are resistant to existing antimycobacterial drugs. A major question in the TB field is: ''what are the mechanisms that allow Mtb to persist in human tissues for decades without replicating, to then abruptly resume growth and cause disease?'' Addressing that question is essential to the development of effective therapeutic intervention strategies. Recent evidence implicates NO as an environmental trigger of mycobacterial persistence (2-5). The latter findings are particularly interesting in light of the fact that inducible NO synthase (iNOS) and therefore NO production is crucial for protection of mice against Mtb (6), and that human macrophages in Mtb-infected tissues express iNOS (2, 7). Another factor associated with latent TB is hypoxia (8). The role of oxygen tension in TB is receiving wide attention, especially because it was demonstrated that rapid withdrawal of oxygen is lethal to Mtb, whereas a gradual depletion allows time for adaptation and bacterial survival (8). Interestingly, a significant overlap exists between the gene expression profiles of Mtb cells treated with NO and that of bacilli cultured under hypoxic conditions (3-5). ...

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Section: Discussionmentioning

confidence: 99%

Mycobacterium tuberculosis DosS is a redox sensor and DosT is a hypoxia sensor

Kumar¹,

Toledo

Patel

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

294

368

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“…The protein concentration for resonance Raman experiments was ϳ20 M in 50 mM Tris-HCl, pH 8.0. sis of the globin domain sequence with those of other globin proteins suggested that the N-terminal domain binds heme, similar to myoglobin, YddV, HemAT, AvGReg, BpeGReg, GsGCS, and HemDGC ( Fig. 1B) (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36). The globin domain of this GcHK displays homology with that of SWMb (34% similarity and 16% identity) and HemAT-Bs (39% similarity and 24% identity).…”

Section: Methodsmentioning

confidence: 99%

“…We designated this gene, Anae109_2438, as gchK (globin-coupled histidine kinase). The globin domain of the GcHK protein should bind heme, in view of its similarity to the amino acid sequences of the globin fold proteins, YddV, HemAT, GRegs, and HemDGC, which are heme-based globin-coupled oxygen sensor enzymes with sufficient heme binding affinity (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36) (Fig. 1, A and B).…”

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confidence: 99%

Identification and Functional and Spectral Characterization of a Globin-coupled Histidine Kinase from Anaeromyxobacter sp. Fw109-5

Kitanishi

Kobayashi

Uchida

et al. 2011

Journal of Biological Chemistry

108

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Two-component signal transduction systems regulate numerous important physiological functions in bacteria. In this study we have identified, cloned, overexpressed, and characterized a dimeric full-length heme-bound (heme:protein, 1:1 stoichiometry) globin-coupled histidine kinase (AfGcHK) from Anaeromyxobacter sp. strain Fw109-5 for the first time. The Fe(III), Fe(II)-O2, and Fe(II)-CO complexes of the protein displayed autophosphorylation activity, whereas the Fe(II) complex had no significant activity. A H99A mutant lost heme binding ability, suggesting that this residue is the heme proximal ligand. Moreover, His-183 was proposed as the autophosphorylation site based on the finding that the H183A mutant protein was not phosphorylated. The phosphate group of autophosphorylated AfGcHK was transferred to Asp-52 and Asp-169 of a response regulator, as confirmed from site-directed mutagenesis experiments. Based on the amino acid sequences and crystal structures of other globin-coupled oxygen sensor enzymes, Tyr-45 was assumed to be the O2 binding site at the heme distal side. The O2 dissociation rate constant, 0.10 s−1, was substantially increased up to 8.0 s−1 upon Y45L mutation. The resonance Raman frequencies representing νFe-O2 (559 cm−1) and νO-O (1149 cm−1) of the Fe(II)-O2 complex of Y45F mutant AfGcHK were distinct from those of the wild-type protein (νFe-O2, 557 cm−1; νO-O, 1141 cm−1), supporting the proposal that Tyr-45 is located at the distal side and forms hydrogen bonds with the oxygen molecule bound to the Fe(II) complex. Thus, we have successfully identified and characterized a novel heme-based globin-coupled oxygen sensor histidine kinase, AfGcHK, in this study.

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“…The O 2 -sensing proteins identified so far include FixL (7), phosphodiesterase A 1 from Acetobacter xylinum (8), Escherichia coli direct oxygen sensor (DOS) 3 (9), and HemAT (10). FixL, A. xylinum phosphodiesterase A1, and E. coli DOS belong to the PAS (PER/ ARNT/SIM) family and contain a heme-bound PAS domain as a sensor, but HemAT is globin-like, belonging to the methyl-accepting chemotaxis protein (MCP) family.…”

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confidence: 99%