Formyltetrahydrofolate synthetase

Himes, Richard H.; Wilder, Teresa

doi:10.1016/0003-9861(68)90323-8

Cited by 27 publications

(11 citation statements)

References 16 publications

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“…The parent strain, JH1005, had a specific activity of 16.5 Ϯ 3.6 nmol/min/mg of protein. This is comparable to the Fhs activity reported for a related species, Enterococcus hirae (formerly Streptococcus fecaelis) (22). Control tubes in which THF was left out had no activity.…”

Section: Resultssupporting

confidence: 83%

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Genetic and physiologic analysis of a formyl-tetrahydrofolate synthetase mutant of Streptococcus mutans

et al. 1997

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Previously we reported that transposon Tn917 mutagenesis of Streptococcus mutans JH1005 yielded an isolate defective in its normal ability to produce a mutacin (P. J. Crowley, J. D. Hillman, and A. S. Bleiweis, abstr. D55, p. 258 in Abstracts of the 95th General Meeting of the American Society for Microbiology 1995Microbiology , 1995. In this report we describe the recovery of the mutated gene by shotgun cloning. Sequence analysis of insert DNA adjacent to Tn917 revealed homology to the gene encoding formyl-tetrahydrofolate synthetase (Fhs) from both prokaryotic and eukaryotic sources. In many bacteria, Fhs catalyzes the formation of 10-formyl-tetrahydrofolate, which is used directly in purine biosynthesis and formylation of Met-tRNA and indirectly in the biosynthesis of methionine, serine, glycine, and thymine. Analysis of the fhs mutant grown anaerobically in a minimal medium demonstrated that the mutant had an absolute dependency only for adenine, although addition of methionine was necessary for normal growth. Coincidently it was discovered that the mutant was sensitive to acidic pH; it grew more slowly than the parent strain on complex medium at pH 5. Complementation of the mutant with an integration vector harboring a copy of fhs restored its ability to grow in minimal medium and at acidic pH as well as to produce mutacin. This represents the first characterization of Fhs in Streptococcus.Streptococcus mutans, an organism associated with the causation of human dental caries, possesses features that enable it to colonize the host, accumulate on teeth, and ultimately produce a pathologic end result. Important structural features associated with virulence include surface adhesins and glucan or fructan capsules (for reviews, see references 26 and 41), which allow adherence to dental surfaces and coherence to other members of the plaque flora. Important physiologic features associated with virulence include the glycolytic conversion of dietary carbohydrates to high levels of lactic acid that contribute to low plaque pH levels and the ability to withstand these acidic conditions by low membrane permeability to protons and high activity of H ϩ /ATPase for increased proton extrusion (1a, 17). The ability to withstand low pH is a trait which also provides this organism a likely selective means by which to dominate its niche in the oral cavity. Its dominance in these microenvironments is thought to be aided by the ability of many strains of S. mutans to produce specific antimicrobial substances, referred to as mutacins (16), that are effective against other strains of S. mutans and related organisms. In some studies (16,40) up to 80% of the strains tested had the ability to produce a mutacin.In order to learn more about the genetic basis of virulence in this cariogenic streptococcus, we used the thermosensitive plasmid pTV1-OK, which harbors the nonconjugative transposon Tn917, to mutagenize the chromosome of this organism. In a previous publication (14), which describes the construction of plasmids used for transp...

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Section: Resultssupporting

confidence: 83%

“…exists as a tetramer with a molecular mass of ϳ230,000 Da consisting of four 58,000-Da monomeric subunits (31,53). The predicted molecular mass, based upon amino acid composition, for the S. mutans Fhs was 59,695 Da, nearly identical to that reported for the monomer from Clostridium as well as other bacterial species (22).…”

Section: Resultssupporting

confidence: 61%

Genetic and physiologic analysis of a formyl-tetrahydrofolate synthetase mutant of Streptococcus mutans

et al. 1997

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“…In procaryotes, monofunctional proteins catalyze these activities, with the known exception of a bifunctional cyclohydrolase-dehydrogenase in Escherichia coli (7) and Clostridium thermoaceticum (18). In Clostridium acidiurici ("Clostridium acidi-urici"), 10-formyl-THF synthetase is a monofunctional protein whose enzymatic and physical properties have been extensively characterized (11).…”

mentioning

confidence: 99%

Cloning and expression in Escherichia coli of the gene for 10-formyltetrahydrofolate synthetase from Clostridium acidiurici ("Clostridium acidi-urici")

Whitehead¹,

Rabinowitz²

1986

J Bacteriol

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The gene for 10-formyltetrahydrofolate synthetase (EC 6.3.4.3) from the purinolytic anaerobic bacterium Clostridium acidiurici ("Clostridium acidi-urici") was cloned into Escherichia coli JM83 with plasmid pUC8. A C. acidiurici genomic library was prepared in E. coli from a partial Sau3A digest and screened with antibody against the synthetase. Of 10 antibody-positive clones, 1 expressed a high level of synthetase activity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis demonstrated that the protein synthesized in E. coli had the same subunit molecular weight as the C. acidiurici enzyme. The gene was located on an 8.3-kilobase genomic insert and appeared to be transcribed from its own promoter. Analysis of genomic digests with a fragment of the synthetase gene indicated that one copy of the gene was present in the C. acidiurici chromosome.

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“…In addition to its biosynthesis from serine described above, 10-CHO-THF can also be formed by the enzymatic activation of formate by the enzyme 10-CHO-THF synthetase (EC 6.3.4.3). It has been proposed that this enzyme is ubiquitous (8,24), based on the recognition of the importance of one-carbon metabolism and on the fact that 10-CHO-THF synthetase activity was detected in all bacteria tested (26). However, it has more recently been reported that the enzyme does not occur in Escherichia coli (5).…”

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confidence: 99%