High-resolution structure of recombinant<i>Trichomonas vaginalis</i>thioredoxin

Iulek, J.; Alphey, M.S.; Westrop, Gareth D.; Coombs, Graham H.; Hunter, William N.

doi:10.1107/s0907444905039946

Cited by 6 publications

(4 citation statements)

References 32 publications

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“…The disulfide bonds were all modeled as a mixture of reduced and oxidized species. A similar photoreduction of the active site disulfide bond in Trichomonas Vaginalis thioredoxin has been reported (32).…”

Section: Methodssupporting

confidence: 73%

Buried S-Nitrosocysteine Revealed in Crystal Structures of Human Thioredoxin^,

2007

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We have determined the 1.65 A crystal structure of human thioredoxin-1 after treatment with S-nitrosoglutathione, providing a high-resolution view of this important protein modification and mechanistic insight into protein transnitrosation. Thioredoxin-1 appears to play an intermediary role in cellular S-nitrosylation and is important in numerous biological and pathobiological activities. S-Nitroso modifications of cysteines 62 and 69 are clearly visible in the structure and display planar cis geometries, whereas cysteines 32, 35, and 73 form intra- and intermolecular disulfide bonds. Surprisingly, the Cys 62 nitroso group is completely buried and pointing to the protein interior yet is the most readily formed at neutral pH. The Cys 69 nitroso group is also protected but requires a higher pH for stable formation. The helix intervening between residues 62 and 69 shifts by approximately 0.5 A to accommodate the SNO groups. The crystallographic asymmetric unit contains three independent molecules of thioredoxin, providing three views of the nitrosated protein. The three molecules are in general agreement but display subtle differences, including both cis and trans conformers for Cys 69 SNO in molecule C, and greater disorder in the Cys 62-Cys 69 helix in molecule B. Possible mechanisms for protein transnitrosation with specific geometric requirements and charge stabilization of the nitroxyl disulfide reaction intermediate are discussed.

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Section: Methodssupporting

confidence: 73%

Buried S-Nitrosocysteine Revealed in Crystal Structures of Human Thioredoxin^,

2007

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“…All the components of this system are found in T . vaginalis [ 12 , 56 – 58 ] and it is possible that SMC acts as an antioxidant in T . vaginalis also.…”

Section: Discussionmentioning

confidence: 99%

Metabolomic profiling and stable isotope labelling of Trichomonas vaginalis and Tritrichomonas foetus reveal major differences in amino acid metabolism including the production of 2-hydroxyisocaproic acid, cystathionine and S-methylcysteine

et al. 2017

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Trichomonas vaginalis and Tritrichomonas foetus are pathogens that parasitise, respectively, human and bovine urogenital tracts causing disease. Using LC-MS, reference metabolomic profiles were obtained for both species and stable isotope labelling with D-[U-13C6] glucose was used to analyse central carbon metabolism. This facilitated a comparison of the metabolic pathways of T. vaginalis and T. foetus, extending earlier targeted biochemical studies. 43 metabolites, whose identities were confirmed by comparison of their retention times with authentic standards, occurred at more than 3-fold difference in peak intensity between T. vaginalis and T. foetus. 18 metabolites that were removed from or released into the medium during growth also showed more than 3-fold difference between the species. Major differences were observed in cysteine and methionine metabolism in which homocysteine, produced as a bi-product of trans-methylation, is catabolised by methionine γ-lyase in T. vaginalis but converted to cystathionine in T. foetus. Both species synthesise methylthioadenosine by an unusual mechanism, but it is not used as a substrate for methionine recycling. T. vaginalis also produces and exports high levels of S-methylcysteine, whereas only negligible levels were found in T. foetus which maintains significantly higher intracellular levels of cysteine. 13C-labeling confirmed that both cysteine and S-methylcysteine are synthesised by T. vaginalis; S-methylcysteine can be generated by recombinant T. vaginalis cysteine synthase using phosphoserine and methanethiol. T. foetus contained higher levels of ornithine and citrulline than T. vaginalis and exported increased levels of putrescine, suggesting greater flux through the arginine dihydrolase pathway. T. vaginalis produced and exported hydroxy acid derivatives of certain amino acids, particularly 2-hydroxyisocaproic acid derived from leucine, whereas negligible levels of these metabolites occurred in T. foetus.

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“…Extensive structural data exists for thioredoxin, with examples of crystal structures available for E.coli ,11, 12 Anabaena ,13 T.vaginalis ,14 and M.tuberculosis 15. Unlike many other thioredoxins, the human cytoplasmic thioredoxin has three cysteine residues (Cys 62, Cys 69, Cys 73) additional to the active site Cys 32 and Cys 35.…”

Section: Introductionmentioning

confidence: 99%