engineering

Naphthoate synthase

Naphthoate synthase is a engineering 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 Naphthoate synthase rather than just read about it. In short: The enzyme 1,4-dihydroxy-2-naphthoyl-CoA synthase (EC 4.1.3.36) catalyzes the sixth step in the biosynthesis of phylloquinone and menaquinone, the two forms of vitamin K. In E. coli, 1,4-dihydroxy-2-naphthoyl-CoA synthase, formerly known as naphthoate synthase, is encoded by menB and uses O-succinylbenzoyl-CoA as a substrate and converts it to 1,4-dihydroxy-2-naphthoyl-CoA.

Key takeaways

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Reference excerpt

The enzyme 1,4-dihydroxy-2-naphthoyl-CoA synthase (EC 4.1.3.36) catalyzes the sixth step in the biosynthesis of phylloquinone and menaquinone, the two forms of vitamin K. In E. coli, 1,4-dihydroxy-2-naphthoyl-CoA synthase, formerly known as naphthoate synthase, is encoded by menB and uses O-succinylbenzoyl-CoA as a substrate and converts it to 1,4-dihydroxy-2-naphthoyl-CoA.

Nomenclature MenB is part of the crotonase fold super family, named after the crotonase fold in their structure. The systematic name for MenB is 4-(2-carboxyphenyl)-4-oxobutanoyl-CoA dehydratase (cyclizing). Other common names include:

Naphthoate synthase 1,4-dihydroxy-2-naphthoate synthase Dihydroxynaphthoate synthase DHNA-CoA synthase

Reaction

It was originally thought that the product of this reaction had an oxygen where the SCoA currently resides, however; new research has shown that MenB only catalyzes the above reaction. There is a different enzyme that cleaves the SCoA and attaches the oxygen.

Structure MenB is composed of two hexamers in an asymmetric unit, these hexamers are each composed of two trimers in an eclipsed arrangement. Each sub unit of the hexamers has three C terminal alpha helices, and a N terminal spiral core. These sub units come together to form the active site of the enzyme. The channel formed by alpha helices that can be seen in the middle of the enzyme leads to the active site. This opening exists on both top and bottom of the enzyme, allowing substrates different entry points to the active site, which rests in the middle of the enzyme. Six different crystal structures have been studied for MenB in Escherichia coli their PDB codes are: 3t88, 3t89, 4els, 4elw, 4elx, and 4i42. Other structures have been solved for this class of enzymes, with PDB accession codes PDB: 1Q51, PDB: 1Q52, PDB: 1RJM, PDB: 1RJN, and PDB: 2IEX.

Homologs Homologous genes MenB exist in many different organisms, such as; Galium mollugo, Geobacillus kaustophilus, Mycobacterium phlei, Mycobacterium tuberculosis, Spinacia oleracea, and Staphylococcus aureus. MenB is only found in biosynthesis pathways in plants and bacteria, it does not exist in any other organisms. However, mammals require vitamin K in their diet because it is vital in the blood clotting process.

Cofactors/Inhibitors MenB does not require any cofactors to catalyze the reaction. In the organism Escherichia coli three inhibitors exist: 1-hydroxy-2-naphthoyl-CoA, 2,3-dihydroxybenzoyl-CoA, and 2,4-dihydroxybenzoyl-CoA.

References

Kolkmann R, Leistner E (1987). "4-(2'-Carboxyphenyl)-4-oxobutyryl coenzyme A ester, an intermediate in vitamin K2 (menaquinone) biosynthesis". Z. Naturforsch. C. 42 (11–12): 1207–14. doi:10.1515/znc-1987-11-1212. PMID 2966501. S2CID 41701934. Meganathan R, Bentley R (1979). "Menaquinone (vitamin K2) biosynthesis: conversion of o-succinylbenzoic acid to 1,4-dihydroxy-2-naphthoic acid by Mycobacterium phlei enzymes". J. Bacteriol. 140 (1): 92–8. doi:10.1128/JB.140.1.92-98.1979. PMC 216783. PMID 500558.

Illustrations

Worked examples

Example 1 — a first encounter with Naphthoate synthase

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

In research: Naphthoate synthase appears in engineering 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 Naphthoate 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: Naphthoate synthase is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 4.1.3, Enzymes of known structure, so understanding it makes those chapters shorter.
In everyday life: Look for Naphthoate 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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How to study Naphthoate synthase in 20 minutes

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Frequently asked questions

What is Naphthoate synthase in simple terms?

Why does Naphthoate synthase matter?

Because it connects several engineering 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 Naphthoate 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 Naphthoate synthase.