Structural Basis for Catalysis by Tryptophan Synthase

Miles, Edith Wilson

doi:10.1002/9780470123102.ch3

Cited by 46 publications

(44 citation statements)

References 159 publications

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“…The trpBA locus of F. tularensis (FTN_1739/ FTT1773 and FTN_1740/FTT1772) encodes proteins with high homology to the TrpB and TrpA proteins from multiple bacteria. TrpA and TrpB are responsible for the last two enzymatic reactions required for tryptophan synthesis: TrpA catalyzes the cleavage of indole glycerol 3-phosphate (IGP) to indole, and TrpB then catalyzes the conversion of indole to tryptophan (26). Because TrpB is required for the final step in tryptophan synthesis, a trpB mutant is predicted to be a tryptophan auxotroph.…”

Section: Resultsmentioning

confidence: 99%

“…F. tularensis contains genes for tryptophan biosynthesis (18), including trpAB, which encode the enzymes that catalyze the last two steps in tryptophan biosynthesis. TrpA catalyzes the cleavage of indole glycerol 3-phosphate (IGP) to indole, and TrpB then catalyzes the conversion of indole to tryptophan; TrpA and TrpB typically form a tryptophan synthase tetramer with two subunits of each (26).…”

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confidence: 99%

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Tryptophan Prototrophy Contributes to Francisella tularensis Evasion of Gamma Interferon-Mediated Host Defense

et al. 2011

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Francisella tularensis is able to survive and replicate within host macrophages, a trait that is associated with the high virulence of this bacterium. The trpAB genes encode the enzymes required for the final two steps in tryptophan biosynthesis, with TrpB being responsible for the conversion of indole to tryptophan. Consistent with this function, an F. tularensis subsp. novicida trpB mutant is unable to grow in defined medium in the absence of tryptophan. The trpB mutant is also attenuated for virulence in a mouse pulmonary model of tularemia. However, the trpB mutant remains virulent in gamma interferon receptor-deficient (IFN-␥R ؊/؊ ) mice, demonstrating that IFN-␥-mediated signaling contributes to clearance of the trpB mutant. IFN-␥ limits intracellular survival of the trpB mutant within bone marrow-derived macrophages from wild-type but not IFN-␥R ؊/؊ mice. An F. tularensis subsp. tularensis trpB mutant is also attenuated for virulence in mice and survival within IFN-␥-treated macrophages, indicating that tryptophan prototrophy is also important in a human-virulent F. tularensis subspecies. These results demonstrate that trpB contributes to F. tularensis virulence by enabling intracellular growth under IFN-␥-mediated tryptophan limitation.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Tryptophan Prototrophy Contributes to Francisella tularensis Evasion of Gamma Interferon-Mediated Host Defense

et al. 2011

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“…Two distinct reactions take place in the ␣-and ␤-active sites that are physically separated but connected by an intramolecular channel (15) as shown in Reactions 2 and 3, The ␣-reaction is a concerted catalytic event involving residues Glu-49 and Asp-60, as determined by kinetic and structural studies carried out on the wild type enzyme as well as on several mutants (2). The ␤-reaction is a more complex process (Scheme 1), requiring the combined action of PLP and several catalytic residues.…”

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confidence: 99%

pH Dependence of Tryptophan Synthase Catalytic Mechanism

Schiaretti¹,

Bettati

Viappiani

et al. 2004

Journal of Biological Chemistry

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“…6). In Arabidopsis Trp biosynthesis takes place in chloroplasts, where TSA and TSB have been suggested to form a complex and convert IGP to Trp (10,23,24). The first step of Trp biosynthesis is catalyzed by anthranilate synthase (AS), which is a rate-limiting enzyme and subject to feedback inhibition by Trp (31).…”

Section: Discussionmentioning

confidence: 99%

“…1A). Trp biosynthesis has been proposed to take place in chloroplasts, and TSA and TSB were considered to form a complex and catalyze the formation of Trp (10,23,24). Previous work has shown that INS could complement Trp auxotrophy of the Escherichia coli Δtrp A strain, which is defective in Trp biosynthesis due to the deletion of TSA (17).…”

Section: Significancementioning

confidence: 99%

Tryptophan-independent auxin biosynthesis contributes to early embryogenesis in Arabidopsis

Wang

Chu

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

180

111

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The phytohormone auxin regulates nearly all aspects of plant growth and development. Tremendous achievements have been made in elucidating the tryptophan (Trp)-dependent auxin biosynthetic pathway; however, the genetic evidence, key components, and functions of the Trp-independent pathway remain elusive. Here we report that the Arabidopsis indole synthase mutant is defective in the long-anticipated Trp-independent auxin biosynthetic pathway and that auxin synthesized through this spatially and temporally regulated pathway contributes significantly to the establishment of the apical-basal axis, which profoundly affects the early embryogenesis in Arabidopsis. These discoveries pave an avenue for elucidating the Trp-independent auxin biosynthetic pathway and its functions in regulating plant growth and development.phytohormone | IAA biosynthesis | tryptophan | embryogenesis | Arabidopsis thaliana

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Structural Basis for Catalysis by Tryptophan Synthase

Cited by 46 publications

References 159 publications

Tryptophan Prototrophy Contributes to Francisella tularensis Evasion of Gamma Interferon-Mediated Host Defense

Tryptophan Prototrophy Contributes to Francisella tularensis Evasion of Gamma Interferon-Mediated Host Defense

pH Dependence of Tryptophan Synthase Catalytic Mechanism

Tryptophan-independent auxin biosynthesis contributes to early embryogenesis in Arabidopsis

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