scholarly journals Mycobacterium tuberculosis SatS is a chaperone for the SecA2 protein export pathway

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Brittany K Miller ◽  
Ryan Hughes ◽  
Lauren S Ligon ◽  
Nathan W Rigel ◽  
Seidu Malik ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Binding Sites ◽  
Protein Export ◽  
Structural Studies ◽  
Molecular Pathway ◽  
Export Pathway ◽  
Export System

The SecA2 protein export system is critical for the virulence of Mycobacterium tuberculosis. However, the mechanism of this export pathway remains unclear. Through a screen for suppressors of a secA2 mutant, we identified a new player in the mycobacterial SecA2 pathway that we named SatS for SecA2 (two) Suppressor. In M. tuberculosis, SatS is required for the export of a subset of SecA2 substrates and for growth in macrophages. We further identify a role for SatS as a protein export chaperone. SatS exhibits multiple properties of a chaperone, including the ability to bind to and protect substrates from aggregation. Our structural studies of SatS reveal a distinct combination of a new fold and hydrophobic grooves resembling preprotein-binding sites of the SecB chaperone. These results are significant in better defining a molecular pathway for M. tuberculosis pathogenesis and in expanding our appreciation of the diversity among chaperones and protein export systems.

scholarly journals The Mycobacterium tuberculosis SecA2 System Subverts Phagosome Maturation To Promote Growth in Macrophages

2012 ◽  
Vol 80 (3) ◽  
pp. 996-1006 ◽  
Author(s):  
Jonathan Tabb Sullivan ◽  
Ellen F. Young ◽  
Jessica R. McCann ◽  
Miriam Braunstein
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Protein Export ◽  
Growth Defect ◽  
Phagosome Maturation ◽  
Wild Type ◽  
Intracellular Growth ◽  
Maturation Arrest ◽  
Content Type ◽  
Late Endosomes ◽  
Export System

The ability ofMycobacterium tuberculosisto grow in macrophages is critical to the virulence of this important pathogen. One wayM. tuberculosisis thought to maintain a hospitable niche in macrophages is by arresting the normal process of phagosomes maturing into acidified phagolysosomes. The process of phagosome maturation arrest byM. tuberculosisis not fully understood, and there has remained a need to firmly establish a requirement for phagosome maturation arrest forM. tuberculosisgrowth in macrophages. Other intracellular pathogens that control the phagosomal environment use specialized protein export systems to deliver effectors of phagosome trafficking to the host cell. InM. tuberculosis, the accessory SecA2 system is a specialized protein export system that is required for intracellular growth in macrophages. In studying the importance of the SecA2 system in macrophages, we discovered that SecA2 is required for phagosome maturation arrest. Shortly after infection, phagosomes containing a ΔsecA2mutant ofM. tuberculosiswere more acidified and showed greater association with markers of late endosomes than phagosomes containing wild-typeM. tuberculosis. We further showed that inhibitors of phagosome acidification rescued the intracellular growth defect of the ΔsecA2mutant, which demonstrated that the phagosome maturation arrest defect of the ΔsecA2mutant is responsible for the intracellular growth defect. This study demonstrates the importance of phagosome maturation arrest forM. tuberculosisgrowth in macrophages, and it suggests there are effectors of phagosome maturation that are exported into the host environment by the accessory SecA2 system.

scholarly journals Author response: Mycobacterium tuberculosis SatS is a chaperone for the SecA2 protein export pathway

2018 ◽  
Author(s):  
Brittany K Miller ◽  
Ryan Hughes ◽  
Lauren S Ligon ◽  
Nathan W Rigel ◽  
Seidu Malik ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Protein Export ◽  
Author Response ◽  
Export Pathway

scholarly journals The fluoride permeation pathway and anion recognition in Fluc family fluoride channels

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Benjamin C McIlwain ◽  
Roja Gundepudi ◽  
B Ben Koff ◽  
Randy B Stockbridge
Keyword(s):  
Binding Sites ◽  
Anion Recognition ◽  
Anion Binding ◽  
Structural Studies ◽  
Planar Bilayer ◽  
X Ray ◽  
X Ray Crystallography ◽  
Molecular Determinants ◽  
Cytoplasmic Accumulation ◽  
Oriented System

Fluc family fluoride channels protect microbes against ambient environmental fluoride by undermining the cytoplasmic accumulation of this toxic halide. These proteins are structurally idiosyncratic, and thus the permeation pathway and mechanism have no analogy in other known ion channels. Although fluoride binding sites were identified in previous structural studies, it was not evident how these ions access aqueous solution, and the molecular determinants of anion recognition and selectivity have not been elucidated. Using x-ray crystallography, planar bilayer electrophysiology and liposome-based assays, we identify additional binding sites along the permeation pathway. We use this information to develop an oriented system for planar lipid bilayer electrophysiology and observe anion block at one of these sites, revealing insights into the mechanism of anion recognition. We propose a permeation mechanism involving alternating occupancy of anion binding sites that are fully assembled only as the substrate approaches.

scholarly journals Inhibitors of Mycobacterium tuberculosis EgtD target both substrate binding sites to limit hercynine production

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thanuja D. Sudasinghe ◽  
Michael T. Banco ◽  
Donald R. Ronning
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Binding Sites ◽  
Enzyme Inhibitor ◽  
Structural Information ◽  
Alkylating Agents ◽  
Enzyme Active Site ◽  
Treatment Regimens ◽  
Domains Of Life ◽  
Substrate Binding Sites

AbstractErgothioneine (EGT) is a low molecular weight histidine betaine essential in all domains of life but only synthesized by selected few organisms. Synthesis of EGT by Mycobacterium tuberculosis (M. tb) is critical for maintaining bioenergetic homeostasis and protecting the bacterium from alkylating agents, oxidative stress, and anti-tubercular drugs. EgtD, an S-adenosylmethionine-dependent methyltransferase (AdoMet), catalyzes the trimethylation of L-Histidine to initiate EGT biosynthesis and this reaction has been shown to be essential for EGT production in mycobacteria and for long-term infection of murine macrophages by M. tb. In this work, library screening and structure-guided strategies identified multiple classes of M. tb EgtD inhibitors that bind in various regions of the enzyme active site. X-ray crystal structures of EgtD-inhibitor complexes confirm that L-Histidine analogs bind solely to the L-Histidine binding site while drug-like inhibitors, such as TGX-221, and S-Glycyl-H-1152 span both the L-Histidine and AdoMet binding sites. These enzyme-inhibitor complexes provide detailed structural information of compound scaffolds useful for developing more potent inhibitors that could shorten Tuberculosis treatment regimens by weakening important bacterial defenses.

scholarly journals A PIP Gets the Plasmodium Protein Export Pathway Going

2012 ◽  
Vol 11 (2) ◽  
pp. 99-100
Author(s):  
Rays H.Y. Jiang ◽  
Matthias Marti
Keyword(s):  
Protein Export ◽  
Export Pathway

scholarly journals The Mycobacterium tuberculosis TrcR Response Regulator Represses Transcription of the Intracellularly Expressed Rv1057 Gene, Encoding a Seven-Bladed β-Propeller

2006 ◽  
Vol 188 (1) ◽  
pp. 150-159 ◽  
Author(s):  
Shelley E. Haydel ◽  
Josephine E. Clark-Curtiss
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Intergenic Region ◽  
Binding Sites ◽  
Response Regulator ◽  
Transcriptional Start Site ◽  
Rich Region ◽  
Gene Encoding ◽  
Human Macrophages ◽  
Intracellular Expression ◽  
Transcribed Sequences

ABSTRACT The Mycobacterium tuberculosis TrcR response regulator binds and regulates its own promoter via an AT-rich sequence. Sequences within this AT-rich region determined to be important for TrcR binding were used to search the M. tuberculosis H37Rv genome to identify additional related TrcR binding sites. A similar AT-rich sequence was identified within the intergenic region located upstream of the Rv1057 gene. In the present work, we demonstrate that TrcR binds to a 69-bp AT-rich sequence within the Rv1057 intergenic region and generates specific contacts on the same side of the DNA helix. An M. tuberculosis trcRS deletion mutant, designated STS10, was constructed and used to determine that TrcR functions as a repressor of Rv1057 expression. Additionally, identification of the Rv1057 transcriptional start site suggests that a SigE-regulated promoter also mediates control of Rv1057 expression. Using selective capture of transcribed sequences (SCOTS) analysis as an evaluation of intracellular expression, Rv1057 was shown to be expressed during early M. tuberculosis growth in human macrophages, and the Rv1057 expression profile correlated with a gene that would be repressed by TrcR. Based on structural predictions, motif analyses, and molecular modeling, Rv1057 consists of a series of antiparallel β-strands which adopt a β-propeller fold, and it was determined to be the only seven-bladed β-propeller encoded in the M. tuberculosis genome. These results provide evidence of TrcR response regulator repression of the Rv1057 β-propeller gene that is expressed during growth of M. tuberculosis within human macrophages.

scholarly journals Structural Studies of GABAA Receptor Binding Sites: Which Experimental Structure Tells us What?

2016 ◽  
Vol 9 ◽  
Author(s):  
Roshan Puthenkalam ◽  
Marcel Hieckel ◽  
Xenia Simeone ◽  
Chonticha Suwattanasophon ◽  
Roman V. Feldbauer ◽  
...  
Keyword(s):  
Gabaa Receptor ◽  
Receptor Binding ◽  
Binding Sites ◽  
Structural Studies ◽  
Experimental Structure
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