science

Shikimate pathway

Shikimate pathway is a science 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 Shikimate pathway rather than just read about it. In short: The shikimate pathway (shikimic acid pathway) is a seven-step metabolic pathway used by bacteria, archaea, fungi, algae, some protozoans, and plants for the biosynthesis of folates and aromatic amino acids (tryptophan, phenylalanine, and tyrosine). This pathway is not found in mammals.

Key takeaways

Shikimate pathway belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Shikimate pathway to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Shikimate pathway from memory before moving on to harder problems.

Reference excerpt

The shikimate pathway (shikimic acid pathway) is a seven-step metabolic pathway used by bacteria, archaea, fungi, algae, some protozoans, and plants for the biosynthesis of folates and aromatic amino acids (tryptophan, phenylalanine, and tyrosine). This pathway is not found in mammals. The five enzymes involved in the shikimate pathway are 3-dehydroquinate dehydratase, shikimate dehydrogenase, shikimate kinase, EPSP synthase, and chorismate synthase. In bacteria and eurkaryotes, the pathway starts with two substrates, phosphoenol pyruvate and erythrose-4-phosphate, are processed by DAHP synthase and 3-dehydroquinate synthase to form 3-dehydroquinate. In archaea, 2-amino-3,7-dideoxy-D-threo-hept-6-ulosonate synthase condenses L-Aspartic-4-semialdehyde with a sugar to form 2-amino-3,7-dideoxy-D-threo-hept-6-ulosonate, which is then turned by 3-dehydroquinate synthase II into 3-dehydroquinate. Both pathways end with chorismate (chrorismic acid), a substrate for the three aromatic amino acids. The fifth enzyme involved is the shikimate kinase, an enzyme that catalyzes the ATP-dependent phosphorylation of shikimate to form shikimate 3-phosphate (shown in the figure below). Shikimate 3-phosphate is then coupled with phosphoenol pyruvate to give 5-enolpyruvylshikimate-3-phosphate via the enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase. Glyphosate, the herbicidal ingredient in Roundup, is an uncompetitive inhibitor of EPSP synthase, acting as a transition state analog that binds more tightly to the EPSPS-S3P complex than PEP and inhibits the shikimate pathway.

Then 5-enolpyruvylshikimate-3-phosphate is transformed into chorismate by a chorismate synthase.

Prephenic acid is then synthesized by a Claisen rearrangement of chorismate by chorismate mutase.

Prephenate is oxidatively decarboxylated with retention of the hydroxyl group to give p-hydroxyphenylpyruvate, which is transaminated using glutamate as the nitrogen source to give tyrosine and α-ketoglutarate.

References

Bibliography

Edwin Haslam (1993). Shikimic Acid: Metabolism and Metabolites (1st ed.). ISBN 0471939994. Brown, Stewart A.; Neish, A. C. (1955). "Shikimic Acid as a Precursor in Lignin Biosynthesis". Nature. 175 (4459): 688–689. Bibcode:1955Natur.175..688B. doi:10.1038/175688a0. ISSN 0028-0836. PMID 14370198. S2CID 4273320. Weinstein, L. H.; Porter, C. A.; Laurencot, H. J. (1962). "Role of the Shikimic Acid Pathway in the Formation of Tryptophan in Higher Plants : Evidence for an Alternative Pathway in the Bean". Nature. 194 (4824): 205–206. Bibcode:1962Natur.194..205W. doi:10.1038/194205a0. ISSN 0028-0836. S2CID 4160308. Wilson, D J; Patton, S; Florova, G; Hale, V; Reynolds, K A (1998). "The shikimic acid pathway and polyketide biosynthesis". Journal of Industrial Microbiology and Biotechnology. 20 (5): 299–303. doi:10.1038/sj.jim.2900527. ISSN 1367-5435. S2CID 41117722.

Illustrations

Worked examples

Example 1 — a first encounter with Shikimate pathway

Start with the simplest possible case. Write down what Shikimate pathway claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Shikimate pathway 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 Shikimate pathway 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 Shikimate pathway

In research: Shikimate pathway appears in science 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 Shikimate pathway 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: Shikimate pathway is common in secondary-school and first-year university syllabi. It links to neighbouring topics Metabolic pathways, so understanding it makes those chapters shorter.
In everyday life: Look for Shikimate pathway 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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How to study Shikimate pathway in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Shikimate pathway means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Shikimate pathway out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Shikimate pathway in simple terms?

Why does Shikimate pathway matter?

Because it connects several science 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 Shikimate pathway?

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 Shikimate pathway.