Regulation of homocysteine metabolism by Mycobacterium tuberculosis S-adenosylhomocysteine hydrolase

Singhal, Abhinav; Arora, Gunjan; Sajid, Andaleeb; Maji, Abhijit; Bhat, Ajay; Virmani, R; Upadhyay, Sandeep; Nandicoori, Vinay Kumar; Sengupta, Shantanu; Singh, Yogendra

doi:10.1038/srep02264

Cited by 47 publications

(35 citation statements)

References 47 publications

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“…For Phase I this included an active nucleotide and amino acid metabolism (Wang et al, 2005), which ceased with cell replication over Phase III as reported under in vivo and in vitro conditions (Wayne & Sohaskey, 2001;Betts et al, 2002). In addition, changes in homocysteine levels as a precursor for cell wall maintenance (Dhiman et al, 2009) and for protein and nucleotide synthesis (Singhal et al, 2013) were detected. MK9 and isoprenoids, both involved in the electron transport chain, seemed to play an essential interconnected role over all three conditions tested (Lee et al, 2008;Dhiman et al, 2009).…”

Section: Discussionmentioning

confidence: 98%

“…Homocysteine, the key intermediate of the sulfur pathway, can be metabolized via cysteine to mycothiol (Zeng et al, 2013) or converted to methionine (Singhal et al, 2013) leading to reduced levels of the latter as detected throughout Phase I, in four out of five mycobacteria tested. M. phlei was the only Mycobacterium species in this study for which no homocysteine was found, but increased cysteine levels were detected.…”

Section: Growth Properties Under Aerated and Hypoxic Cultivationmentioning

confidence: 99%

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Metabolite analysis of Mycobacterium species under aerobic and hypoxic conditions reveals common metabolic traits

Drapal

Wheeler²,

Fraser

2016

Microbiology

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A metabolite profiling approach has been implemented to elucidate metabolic adaptation at set culture conditions in five Mycobacterium species (two fast-and three slow-growing) with the potential to act as model organisms for Mycobacterium tuberculosis (Mtb). Analysis has been performed over designated growth phases and under representative environments (nutrient and oxygen depletion) experienced by Mtb during infection. The procedure was useful in determining a range of metabolites (60-120 compounds) covering nucleotides, amino acids, organic acids, saccharides, fatty acids, glycerols, -esters, -phosphates and isoprenoids. Among these classes of compounds, key biomarker metabolites, which can act as indicators of pathway/process activity, were identified. In numerous cases, common metabolite traits were observed for all five species across the experimental conditions (e.g. uracil indicating DNA repair). Amino acid content, especially glutamic acid, highlighted the different properties between the fast-and slowgrowing mycobacteria studied (e.g. nitrogen assimilation). The greatest similarities in metabolite composition between fast-and slow-growing mycobacteria were apparent under hypoxic conditions. A comparison to previously reported transcriptomic data revealed a strong correlation between changes in transcription and metabolite content. Collectively, these data validate the changes in the transcription at the metabolite level, suggesting transcription exists as one of the predominant modes of cellular regulation in Mycobacterium. Sectors with restricted correlation between metabolites and transcription (e.g. hypoxic cultivation) warrant further study to elucidate and exploit post-transcriptional modes of regulation. The strong correlation between the laboratory conditions used and data derived from in vivo conditions, indicate that the approach applied is a valuable addition to our understanding of cell regulation in these Mycobacterium species.

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Section: Discussionmentioning

confidence: 98%

Section: Growth Properties Under Aerated and Hypoxic Cultivationmentioning

confidence: 99%

Metabolite analysis of Mycobacterium species under aerobic and hypoxic conditions reveals common metabolic traits

Drapal

Wheeler²,

Fraser

2016

Microbiology

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“…Similar co-expression system has been efficiently used to assess the phosphorylation in previous studies (54,57,62,69). The purified proteins were analyzed for the presence of acetylation by mass spectrometry.…”

Section: Validation Of Rv0998-mediated Lysine Acetylation and Role Ofmentioning

confidence: 99%

Systematic Analysis of Mycobacterial Acylation Reveals First Example of Acylation-mediated Regulation of Enzyme Activity of a Bacterial Phosphatase

Singhal

Arora

Virmani

et al. 2015

Journal of Biological Chemistry

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Background: Post-translational modifications regulate Mycobacterium tuberculosis physiology and pathogenesis. Results: Several novel signal transduction proteins are regulated by lysine acylation, including the virulence-associated proteintyrosine phosphatase PtpB. Conclusion: M. tuberculosis lysine acylation-regulated pathways affect other signal transduction modules.Significance: This is the first report of acylation-dependent regulation of enzyme activity of a bacterial phosphatase.

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“…3, red brackets), and in M. tuberculosis SAHH, the conserved threonines were identified as a site of posttranslational modification by phosphorylation and were required for enzymatic activity (33). Phosphorylation of the conserved threonines, in the NAD ϩ binding pocket, generated an inactive enzyme by preventing NAD ϩ binding (33). The conservation of these threonines could indicate a site of posttranslational modification by phosphorylation in M. jannaschii.…”

Section: Discussionmentioning

confidence: 99%

“…Interestingly, a group of three threonine residues (T159 to T161 [M. jannaschii numbering]) involved in cofactor binding are also highly conserved (Fig. 3, red brackets), and in M. tuberculosis SAHH, the conserved threonines were identified as a site of posttranslational modification by phosphorylation and were required for enzymatic activity (33). Phosphorylation of the conserved threonines, in the NAD ϩ binding pocket, generated an inactive enzyme by preventing NAD ϩ binding (33).…”

Section: Discussionmentioning

confidence: 99%

S-Inosyl-l-Homocysteine Hydrolase, a Novel Enzyme Involved inS-Adenosyl-l-Methionine Recycling

Miller

White

2015

J Bacteriol

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S-Adenosyl-L-homocysteine, the product of S-adenosyl-L-methionine (SAM) methyltransferases, is known to be a strong feedback inhibitor of these enzymes. A hydrolase specific for S-adenosyl-L-homocysteine produces L-homocysteine, which is remethylated to methionine and can be used to regenerate SAM. Here, we show that the annotated S-adenosyl-L-homocysteine hydrolase in Methanocaldococcus jannaschii is specific for the hydrolysis and synthesis of S-inosyl-L-homocysteine, not S-adenosyl-L-homocysteine. This is the first report of an enzyme specific for S-inosyl-L-homocysteine. As with S-adenosyl-L-homocysteine hydrolase, which shares greater than 45% sequence identity with the M. jannaschii homologue, the M. jannaschii enzyme was found to copurify with bound NAD ؉ and has K m values of 0.64 ؎ 0.4 mM, 0.0054 ؎ 0.006 mM, and 0.22 ؎ 0.11 mM for inosine, L-homocysteine, and S-inosyl-L-homocysteine, respectively. No enzymatic activity was detected with S-adenosyl-L-homocysteine as the substrate in either the synthesis or hydrolysis direction. These results prompted us to redesignate the M. jannaschii enzyme an S-inosyl-L-homocysteine hydrolase (SIHH). Identification of SIHH demonstrates a modified pathway in this methanogen for the regeneration of SAM from S-adenosyl-L-homocysteine that uses the deamination of S-adenosyl-L-homocysteine to form S-inosyl-L-homocysteine. IMPORTANCEIn strictly anaerobic methanogenic archaea, such as Methanocaldococcus jannaschii, canonical metabolic pathways are often not present, and instead, unique pathways that are deeply rooted on the phylogenetic tree are utilized by the organisms. Here, we discuss the recycling pathway for S-adenosyl-L-homocysteine, produced from S-adenosyl-L-methionine (SAM)-dependent methylation reactions, which uses a hydrolase specific for S-inosyl-L-homocysteine, an uncommon metabolite. Identification of the pathways and the enzymes involved in the unique pathways in the methanogens will provide insight into the biochemical reactions that were occurring when life originated. The recycling of S-adenosyl-L-methionine (SAM)-derived metabolites in Methanocaldococcus jannaschii was recently shown to use a novel enzyme, 5=-deoxyadenosine deaminase (DadD) (1). DadD deaminates three SAM-derived enzymatic products (5=-methylthioadenosine, 5=-deoxyadenosine, and S-adenosyl-L-homocysteine) to produce the inosine analogs ( Fig. 1) (1). The canonical pathway for recycling S-adenosyl-L-homocysteine (SAH) produced from SAM-dependent methyltransferases (2-4) proceeds in a three-step recycling pathway back to SAM (Fig. 2A). SAH is first hydrolyzed to produce adenosine and homocysteine using S-adenosyl-L-homocysteine hydrolase (SAHH). Homocysteine is then methylated by methionine synthase to produce methionine (5). The last step in the pathway is the generation of SAM by combining the adenosyl moiety of ATP with methionine to produce SAM, pyrophosphate, and phosphate (Fig. 2), catalyzed by SAM synthase (6). A similar pathway has been established in M. jannaschii but with ...

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Regulation of homocysteine metabolism by Mycobacterium tuberculosis S-adenosylhomocysteine hydrolase

Cited by 47 publications

References 47 publications

Metabolite analysis of Mycobacterium species under aerobic and hypoxic conditions reveals common metabolic traits

Metabolite analysis of Mycobacterium species under aerobic and hypoxic conditions reveals common metabolic traits

Systematic Analysis of Mycobacterial Acylation Reveals First Example of Acylation-mediated Regulation of Enzyme Activity of a Bacterial Phosphatase

S-Inosyl-l-Homocysteine Hydrolase, a Novel Enzyme Involved inS-Adenosyl-l-Methionine Recycling

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