Purification and characterization of S-adenosylhomocysteine deaminase from streptonigrin-producing Streptomyces flocculus

Zulty, James J.; Speedie, Marilyn K.

doi:10.1128/jb.171.12.6840-6844.1989

Cited by 13 publications

(8 citation statements)

References 17 publications

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“…This high affinity for SAH was nevertheless tempered by a 30-fold-lower V max compared with that of adenosine as a substrate. One explanation for the observed activity on SAH could be that the physiological role for Hp0267 is as an SAH deaminase; however, there is only one such enzyme described in the literature (from Streptomyces flocculus), and the specifics of this degradation pathway are uncertain (33,34). In addition, it was shown that Tm0936 catalyzes the deamination of adenosine nearly as efficiently as for SAH, and furthermore, the T. maritima genome lacks a homolog to adenosine deaminase (25).…”

Section: Resultsmentioning

confidence: 99%

Identification of a New Class of Adenosine Deaminase from Helicobacter pylori with Homologs among Diverse Taxa

Miller

Maier

2013

Journal of Bacteriology

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Early studies of Helicobacter pylori's nutritional requirements alluded to a complete purine salvage network in this organism. Recently, this hypothesis was confirmed in two strains of H. pylori, whose purine requirements were satisfied by any single purine base or nucleoside. Most of the purine conversion enzymes in H. pylori have been studied using mutant analysis; however, the gene encoding adenosine deaminase (ADD) in H. pylori remained unidentified. Through stepwise protein purification followed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF), we discovered that H. pylori ADD is encoded by hp0267, an apparently essential gene. Hp0267 shares no sequence homology with previously characterized ADDs, yet both are members of the amidohydrolase superfamily. Hp0267 is grouped within cog0402, while other ADDs studied to date are found in cog1816. The hp0267 locus was previously misannotated as encoding a chlorohydrolase. Using purified recombinant Hp0267, we determined the enzyme's pH optimum, temperature optimum, substrate specificity, and estimated kinetic constants. In contrast to other known ADDs, Hp0267 contains Fe(II) as the relevant metal ligand. Furthermore, Hp0267 exhibits very low deaminase activity on 2=-deoxyadenosine, a substrate that is readily hydrolyzed by cog1816 ADDs. Our preliminary comparative genomic analysis suggests that Hp0267 represents a second enzyme class of adenosine deaminase whose phyletic distribution among prokaryotes is broad.

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Section: Resultsmentioning

confidence: 99%

Identification of a New Class of Adenosine Deaminase from Helicobacter pylori with Homologs among Diverse Taxa

Miller

Maier

2013

Journal of Bacteriology

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“…DNA is comprised of different nucleobases, and the inosine analogue of SAH, S-inosyl-L-homocysteine (SIH, 4c) has been found in the archaeon Methanocaldococcus jannaschii and the bacterium Streptomyces flocculus. 45,64,65 Indeed, SIH seems to be part of an alternative SAM and L-methionine recycling pathway in archaea. 45,66 The experiment using 7-deazaadenosine described above already showed that, in principle, cofactor building blocks with altered nucleobases can be fed in the cycle.…”

Section: Regeneration Of Sam Analogues Is Possible With Nucleobase Modificationsmentioning

confidence: 99%

A bicyclic S-adenosylmethionine regeneration system applicable with different nucleosides or nucleotides as cofactor building blocks

et al. 2021

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“…1). SIH is not a typical metabolite and has been identified only in Streptomyces flocculus (25). Here, we show that the annotated SAHH in M. jannaschii (MJ1388) does not accept SAH as a substrate and instead exclusively uses SIH.…”

Section: Discussionmentioning

confidence: 87%

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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Purification and characterization of S-adenosylhomocysteine deaminase from streptonigrin-producing Streptomyces flocculus

Cited by 13 publications

References 17 publications

Identification of a New Class of Adenosine Deaminase from Helicobacter pylori with Homologs among Diverse Taxa

Identification of a New Class of Adenosine Deaminase from Helicobacter pylori with Homologs among Diverse Taxa

A bicyclic S-adenosylmethionine regeneration system applicable with different nucleosides or nucleotides as cofactor building blocks

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

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