biology

Indole-3-glycerol-phosphate synthase

Indole-3-glycerol-phosphate synthase is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Indole-3-glycerol-phosphate synthase rather than just read about it. In short: The enzyme indole-3-glycerol-phosphate synthase (IGPS) (EC 4.1.1.48) catalyzes the chemical reaction 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate ⇌ {\displaystyle \rightleftharpoons } 1-C-(indol-3-yl)-glycerol 3-phosphate + CO2 + H2O This enzyme belongs to the family of lyases, to be specific, the carboxy-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is 1-(2-carboxyphe…

Key takeaways

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Reference excerpt

The enzyme indole-3-glycerol-phosphate synthase (IGPS) (EC 4.1.1.48) catalyzes the chemical reaction

1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate ⇌ {\displaystyle \rightleftharpoons } 1-C-(indol-3-yl)-glycerol 3-phosphate + CO2 + H2O This enzyme belongs to the family of lyases, to be specific, the carboxy-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose-5-phosphate carboxy-lyase [cyclizing 1-C-(indol-3-yl)glycerol-3-phosphate-forming]. Other names in common use include indoleglycerol phosphate synthetase, indoleglycerol phosphate synthase, indole-3-glycerophosphate synthase, 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose-5-phosphate, and carboxy-lyase (cyclizing). This enzyme participates in phenylalanine, tyrosine and tryptophan biosynthesis and two-component system - general. It employs one cofactor, pyruvate.

Structural studies In some bacteria, IGPS is a single chain enzyme. In others, such as Escherichia coli, it is the N-terminal domain of a bifunctional enzyme that also catalyses N-(5'-phosphoribosyl)anthranilate isomerase (EC 5.3.1.24) (PRAI) activity, the third step of tryptophan biosynthesis. In fungi, IGPS is the central domain of a trifunctional enzyme that contains a PRAI C-terminal domain and a glutamine amidotransferase (EC 2.4.2.-) (GATase) N-terminal domain. A structure of the IGPS domain of the bifunctional enzyme from the mesophilic bacterium E. coli (eIGPS) has been compared with the monomeric indole-3-glycerol phosphate synthase from the hyperthermophilic archaeon Sulfolobus solfataricus (sIGPS). Both are single-domain (beta/alpha)8 barrel proteins, with one (eIGPS) or two (sIGPS) additional helices inserted before the first beta strand. As of late 2007, 11 structures have been solved for this class of enzymes, with PDB accession codes PDB: 1A53, PDB: 1I4N, PDB: 1J5T, PDB: 1JCM, PDB: 1JUK, PDB: 1JUL, PDB: 1LBF, PDB: 1LBL, PDB: 1PII, PDB: 1VC4, and PDB: 2C3Z.

References

Further reading Creighton TE, Yanofsky C (1966). "Indole-3-glycerol phosphate synthetase of Escherichia coli, an enzyme of the tryptophan operon". J. Biol. Chem. 241 (20): 4616–24. doi:10.1016/S0021-9258(18)99693-6. PMID 5332729. Creighton TE; Yanofsky C (1970). "Chorismate to tryptophan (Escherichia coli)—anthranilate synthetase, PR transferase, PRA isomerase, InGP synthetase, tryptophan synthetase". Chorismate to tryptophan (Escherichia coli) - Anthranilate synthetase, PR transferase, PRA isomerase, InGP synthetase, tryptophan synthetase. Methods Enzymol. Vol. 17A. pp. 365–380. doi:10.1016/0076-6879(71)17215-1. ISBN 978-0-12-181874-6. Kung CC, Huang WN, Huang YC, Yeh KC (2006). "Proteomic survey of copper-binding proteins in Arabidopsis roots by immobilized metal affinity chromatography and mass spectrometry". Proteomics. 6 (9): 2746–58. doi:10.1002/pmic.200500108. PMID 16526091. S2CID 25896917.

Illustrations

Worked examples

Example 1 — a first encounter with Indole-3-glycerol-phosphate synthase

Start with the simplest possible case. Write down what Indole-3-glycerol-phosphate synthase claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Indole-3-glycerol-phosphate synthase before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Indole-3-glycerol-phosphate synthase ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Indole-3-glycerol-phosphate synthase

In research: Indole-3-glycerol-phosphate synthase appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Indole-3-glycerol-phosphate synthase in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Indole-3-glycerol-phosphate synthase is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 4.1.1, EC 4.1 stubs, Enzymes of known structure, so understanding it makes those chapters shorter.
In everyday life: Look for Indole-3-glycerol-phosphate synthase outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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Frequently asked questions

What is Indole-3-glycerol-phosphate synthase in simple terms?

The enzyme indole-3-glycerol-phosphate synthase (IGPS) (EC 4.1.1.48) catalyzes the chemical reaction 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate ⇌ {\displaystyle \rightleftharpoons } 1-C-(indol-3-yl)-glycerol 3-phosphate + CO2 + H2O This enzyme belongs to the family of lyases, to be spe…

Why does Indole-3-glycerol-phosphate synthase matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Indole-3-glycerol-phosphate synthase?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Indole-3-glycerol-phosphate synthase.