biology

Rieske protein

Rieske protein 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 Rieske protein rather than just read about it. In short: Rieske proteins are iron–sulfur protein (ISP) components of cytochrome bc1 complexes and cytochrome b6f complexes and are responsible for electron transfer in some biological systems. John S.

Key takeaways

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

Reference excerpt

Rieske proteins are iron–sulfur protein (ISP) components of cytochrome bc1 complexes and cytochrome b6f complexes and are responsible for electron transfer in some biological systems. John S. Rieske and co-workers first discovered the protein and in 1964 isolated an acetylated form of the bovine mitochondrial protein. In 1979, Trumpower's team isolated the "oxidation factor" from bovine mitochondria and showed it was a reconstitutively-active form of the Rieske iron-sulfur protein. It is a unique [2Fe-2S] cluster in that one of the two Fe atoms is coordinated by two histidine residues rather than two cysteine residues. They have since been found in plants, animals, and bacteria with widely ranging electron reduction potentials from -150 to +400 mV.

Biological function Ubiquinol-cytochrome-c reductase (also known as bc1 complex or complex III) is an enzyme complex of bacterial and mitochondrial oxidative phosphorylation systems. It catalyses the oxidation-reduction reaction of the mobile components ubiquinol and cytochrome c, contributing to an electrochemical potential difference across the mitochondrial inner or bacterial membrane, which is linked to ATP synthesis. The complex consists of three subunits in most bacteria, and nine in mitochondria: both bacterial and mitochondrial complexes contain cytochrome b and cytochrome c1 subunits, and an iron–sulfur 'Rieske' subunit, which contains a high potential 2Fe-2S cluster. The mitochondrial form also includes six other subunits that do not possess redox centres. Plastoquinone-plastocyanin reductase (b6f complex), present in cyanobacteria and the chloroplasts of plants, catalyses the oxidoreduction of plastoquinol and cytochrome f. This complex, which is functionally similar to ubiquinol-cytochrome c reductase, comprises cytochrome b6, cytochrome f and Rieske subunits. The Rieske subunit acts by binding either a ubiquinol or plastoquinol anion, transferring an electron to the 2Fe-2S cluster, then releasing the electron to the cytochrome c or cytochrome f heme iron. The reduction of the Rieske center increases the affinity of the subunit by several orders of magnitude, stabilizing the semiquinone radical at the Q(P) site. The Rieske domain has a [2Fe-2S] center. Two conserved cysteines coordinate one Fe ion while the other Fe ion is coordinated by two conserved histidines. The 2Fe-2S cluster is bound in the highly conserved C-terminal region of the Rieske subunit.

Rieske protein family The homologues of the Rieske proteins include ISP components of cytochrome b6f complex, aromatic-ring-hydroxylating dioxygenases (phthalate dioxygenase, benzene, naphthalene and toluene 1,2-dioxygenases) and arsenite oxidase (EC 1.20.98.1). Comparison of amino acid sequences has revealed the following consensus sequence:

Cys-Xaa-His-(Xaa)15–18-Cys-Xaa-Xaa-His

3D structure The overall fold of Rieske proteins, comprising two subdomains, is dominated by antiparallel β-structure and contains variable numbers of α-helices. The smaller "cluster-binding" subdomains in mitochondrial and chloroplast proteins are virtually identical, whereas the large subdomains are substantially different in spite of a common folding topology. The [Fe2S2] cluster-binding subdomains have the topology of an incomplete antiparallel β-barrel. One iron atom of the Rieske [Fe2S2] cluster in the domain is coordinated by two cysteine residues and the other is coordinated by two histidine residues through the Nδ atoms. The ligands coordinating the cluster originate from two loops; each loop contributes one Cys and one His.

Subfamilies Rieske iron–sulfur protein, C-terminal InterPro: IPR005805 Arsenite oxidase, small subunit InterPro: IPR014067

Human proteins containing this domain AIFM3; RFESD; UQCRFS1;

References

Illustrations

Worked examples

Example 1 — a first encounter with Rieske protein

Start with the simplest possible case. Write down what Rieske protein 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 Rieske protein 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 Rieske protein 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 Rieske protein

In research: Rieske protein 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 Rieske protein 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: Rieske protein is common in secondary-school and first-year university syllabi. It links to neighbouring topics Electron-transfer proteins, Iron–sulfur proteins, Peripheral membrane proteins, so understanding it makes those chapters shorter.
In everyday life: Look for Rieske protein 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 Rieske protein in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Rieske protein 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 Rieske protein out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rieske protein in simple terms?

Rieske proteins are iron–sulfur protein (ISP) components of cytochrome bc1 complexes and cytochrome b6f complexes and are responsible for electron transfer in some biological systems. John S.

Why does Rieske protein 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 Rieske protein?

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 Rieske protein.