Proton ATPase

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Proton ATPase, graphic representation Proton ATPase cartoon overview.png
Proton ATPase, graphic representation

In the field of enzymology, a proton ATPase, or H+-ATPase, is an enzyme that catalyzes the following chemical reaction:

Contents

ATP + H
2O + H+
in ADP + phosphate + H+
out

The 3 substrates of this enzyme are ATP, H
2O , and H+
 , whereas its 3 products are ADP, phosphate, and H+
 .

Proton ATPases are divided into three groups [1] as outlined below:

P-type proton ATPase

P-type ATPases form a covalent phosphorylated (hence the symbol ’P') intermediate as part of its reaction cycle. P-type ATPases undergo major conformational changes during the catalytic cycle. P-type ATPases are not evolutionary related to V- and F-type ATPases. [1]

Plasma membrane H+-ATPase

P-type proton ATPase [2] [3] [4] [5] (or plasma membrane H+
-ATPase) is found in the plasma membranes of eubacteria, archaea, protozoa, fungi and plants. Here it serves as a functional equivalent to the Na+/K+ ATPase of animal cells; i.e. it energizes the plasma membrane by forming an electrochemical gradient of protons (Na+ in animal cells), that in turn drives secondary active transport processes across the membrane. The plasma membrane H+-ATPase is a P3A ATPase with a single polypeptide of 70-100 kDa.

Gastric H+/K+ ATPase

Animals have a gastric hydrogen potassium ATPase or H+/K+ ATPase that belongs to the P-type ATPase family and functions as an electroneutral proton pump. This pump is found in the plasma membrane of cells in the gastric mucosa and functions to acidify the stomach. [6] This enzyme is a P2C ATPase, characterized by having a supporting beta-subunit, and is closely related to the Na+/K+ ATPase.

V-type proton ATPase

V-type proton ATPase [7] [8] [9] (or V-ATPase) translocate protons into intracellular organelles other than mitochondria and chloroplasts, but in certain cell types they are also found in the plasma membrane. V-type ATPases acidify the lumen of the vacuole (hence the symbol 'V') of fungi and plants, and that of the lysosome in animal cells. Furthermore, they are found in endosomes, clathrin coated vesicles, hormone storage granules, secretory granules, Golgi vesicles and in the plasma membrane of a variety of animal cells. Like F-type ATPases, V-type ATPases are composed of multiple subunits and carry out rotary catalysis. [10] The reaction cycle involves tight binding of ATP but proceeds without formation of a covalent phosphorylated intermediate. V-type ATPases are evolutionary related to F-type ATPases. [11]

F-type proton ATPase

F-type proton ATPase [12] [13] (or F-ATPase) typically operates as an ATP synthase that dissipates a proton gradient rather than generating one; i.e. protons flow in the reverse direction compared to V-type ATPases. In eubacteria, F-type ATPases are found in plasma membranes. In eukaryotes, they are found in the mitochondrial inner membranes and in chloroplast thylakoid membranes. Like V-type ATPases, F-type ATPases are composed of multiple subunits and carry out rotary catalysis. The reaction cycle involves tight binding of ATP but proceeds without formation of a covalent phosphorylated intermediate. F-type ATPases are evolutionary related to V-type ATPases. [11]

Related Research Articles

A proton pump is an integral membrane protein pump that builds up a proton gradient across a biological membrane. Proton pumps catalyze the following reaction:

In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient. This process is in contrast to passive transport, which allows molecules or ions to move down their concentration gradient, from an area of high concentration to an area of low concentration, without energy.

<span class="mw-page-title-main">ATPase</span> Dephosphorylation enzyme

ATPases (EC 3.6.1.3, Adenosine 5'-TriPhosphatase, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, SV40 T-antigen, ATP hydrolase, complex V (mitochondrial electron transport), (Ca2+ + Mg2+)-ATPase, HCO3−-ATPase, adenosine triphosphatase) are a class of enzymes that catalyze the decomposition of ATP into ADP and a free phosphate ion or the inverse reaction. This dephosphorylation reaction releases energy, which the enzyme (in most cases) harnesses to drive other chemical reactions that would not otherwise occur. This process is widely used in all known forms of life.

<span class="mw-page-title-main">ATP synthase</span> Enzyme

ATP synthase is an enzyme that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi). ATP synthase is a molecular machine. The overall reaction catalyzed by ATP synthase is:

Dale Sanders, FRS is a plant biologist and former Director of the John Innes Centre, an institute for research in plant sciences and microbiology in Norwich, England.

<span class="mw-page-title-main">F-ATPase</span> Membrane protein

F-ATPase, also known as F-Type ATPase, is an ATPase/synthase found in bacterial plasma membranes, in mitochondrial inner membranes, and in chloroplast thylakoid membranes. It uses a proton gradient to drive ATP synthesis by allowing the passive flux of protons across the membrane down their electrochemical gradient and using the energy released by the transport reaction to release newly formed ATP from the active site of F-ATPase. Together with V-ATPases and A-ATPases, F-ATPases belong to superfamily of related rotary ATPases.

<span class="mw-page-title-main">Electrochemical gradient</span> Gradient of electrochemical potential, usually for an ion that can move across a membrane

An electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can move across a membrane. The gradient consists of two parts:

<span class="mw-page-title-main">V-ATPase</span> Family of transport protein complexes

Vacuolar-type ATPase (V-ATPase) is a highly conserved evolutionarily ancient enzyme with remarkably diverse functions in eukaryotic organisms. V-ATPases acidify a wide array of intracellular organelles and pumps protons across the plasma membranes of numerous cell types. V-ATPases couple the energy of ATP hydrolysis to proton transport across intracellular and plasma membranes of eukaryotic cells. It is generally seen as the polar opposite of ATP synthase because ATP synthase is a proton channel that uses the energy from a proton gradient to produce ATP. V-ATPase however, is a proton pump that uses the energy from ATP hydrolysis to produce a proton gradient.

<span class="mw-page-title-main">Ion transporter</span> Transmembrane protein that moves ions across a biological membrane

In biology, a transporter is a transmembrane protein that moves ions across a biological membrane to accomplish many different biological functions, including cellular communication, maintaining homeostasis, energy production, etc. There are different types of transporters including pumps, uniporters, antiporters, and symporters. Active transporters or ion pumps are transporters that convert energy from various sources—including adenosine triphosphate (ATP), sunlight, and other redox reactions—to potential energy by pumping an ion up its concentration gradient. This potential energy could then be used by secondary transporters, including ion carriers and ion channels, to drive vital cellular processes, such as ATP synthesis.

Gastric hydrogen potassium ATPase, also known as H+/K+ ATPase, is an enzyme which functions to acidify the stomach. It is a member of the P-type ATPases, also known as E1-E2 ATPases due to its two states.

<span class="mw-page-title-main">P-type ATPase</span>

The P-type ATPases, also known as E1-E2 ATPases, are a large group of evolutionarily related ion and lipid pumps that are found in bacteria, archaea, and eukaryotes. P-type ATPases are α-helical bundle primary transporters named based upon their ability to catalyze auto- (or self-) phosphorylation (hence P) of a key conserved aspartate residue within the pump and their energy source, adenosine triphosphate (ATP). In addition, they all appear to interconvert between at least two different conformations, denoted by E1 and E2. P-type ATPases fall under the P-type ATPase (P-ATPase) Superfamily (TC# 3.A.3) which, as of early 2016, includes 20 different protein families.

<span class="mw-page-title-main">ATP5F1A</span> Protein-coding gene in the species Homo sapiens

ATP synthase F1 subunit alpha, mitochondrial is an enzyme that in humans is encoded by the ATP5F1A gene.

<span class="mw-page-title-main">ATP6V0C</span> Protein-coding gene in the species Homo sapiens

V-type proton ATPase 16 kDa proteolipid subunit is an enzyme that in humans is encoded by the ATP6V0C gene.

<span class="mw-page-title-main">ATP6V1A</span> Protein-coding gene in the species Homo sapiens

V-type proton ATPase catalytic subunit A is an enzyme that in humans is encoded by the ATP6V1A gene.

<span class="mw-page-title-main">ATP6V1G2</span>

V-type proton ATPase subunit G 2 is an enzyme that in humans is encoded by the ATP6V1G2 gene.

<span class="mw-page-title-main">ATP6V1G3</span> Protein-coding gene in the species Homo sapiens

V-type proton ATPase subunit G 3 is an enzyme that in humans is encoded by the ATP6V1G3 gene.

<span class="mw-page-title-main">ATP6V0E1</span> Protein-coding gene in the species Homo sapiens

V-type proton ATPase subunit e 1 is an enzyme that in humans is encoded by the ATP6V0E1 gene.

<span class="mw-page-title-main">ATP5D</span> Protein-coding gene in the species Homo sapiens

ATP synthase subunit delta, mitochondrial, also known as ATP synthase F1 subunit delta or F-ATPase delta subunit is an enzyme that in humans is encoded by the ATP5F1D gene. This gene encodes a subunit of mitochondrial ATP synthase. Mitochondrial ATP synthase catalyzes ATP synthesis, utilizing an electrochemical gradient of protons across the inner membrane during oxidative phosphorylation.

Propionigenium modestum is a species of gram-negative, strictly anaerobic bacteria. It is rod-shaped and around 0.5-0.6 x 0.5-2.0μm in size. It is important in the elucidation of mechanism of ATP synthase.

The P-type plasma membrane H+
-ATPase is found in plants and fungi. For the gastric H+
/K+
 ATPase, see Hydrogen potassium ATPase.

References

  1. 1 2 Pedersen PL, Carafoli E (1987). "Ion motive ATPases. I. Ubiquity, properties, and significance to cell function". Trends in Biochemical Sciences. 12: 146–50. doi:10.1016/0968-0004(87)90071-5.
  2. ↑ Goffeau A, Slayman CW (December 1981). "The proton-translocating ATPase of the fungal plasma membrane". Biochimica et Biophysica Acta (BBA) - Reviews on Bioenergetics. 639 (3–4): 197–223. doi:10.1016/0304-4173(81)90010-0. PMID   6461354.
  3. ↑ Morsomme P, Slayman CW, Goffeau A (November 2000). "Mutagenic study of the structure, function and biogenesis of the yeast plasma membrane H(+)-ATPase". Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes. 1469 (3): 133–57. doi:10.1016/S0304-4157(00)00015-0. PMID   11063881.
  4. ↑ Palmgren MG (June 2001). "PLANT PLASMA MEMBRANE H+-ATPases: Powerhouses for Nutrient Uptake". Annual Review of Plant Physiology and Plant Molecular Biology. 52: 817–845. doi:10.1146/annurev.arplant.52.1.817. PMID   11337417.
  5. ↑ Morth JP, Pedersen BP, Buch-Pedersen MJ, Andersen JP, Vilsen B, Palmgren MG, Nissen P (January 2011). "A structural overview of the plasma membrane Na+,K+-ATPase and H+-ATPase ion pumps". Nature Reviews. Molecular Cell Biology. 12 (1): 60–70. doi:10.1038/nrm3031. PMID   21179061.
  6. ↑ Sachs G, Shin JM, Briving C, Wallmark B, Hersey S (1995). "The pharmacology of the gastric acid pump: the H+,K+ ATPase". Annu Rev Pharmacol Toxicol. 35: 277–305. doi:10.1146/annurev.pa.35.040195.001425. PMID   7598495.
  7. ↑ Beyenbach KW, Wieczorek H (February 2006). "The V-type H+ ATPase: molecular structure and function, physiological roles and regulation". The Journal of Experimental Biology. 209 (Pt 4): 577–89. doi: 10.1242/jeb.02014 . PMID   16449553.
  8. ↑ Nelson N (November 1992). "The vacuolar H(+)-ATPase--one of the most fundamental ion pumps in nature". The Journal of Experimental Biology. 172: 19–27. PMID   1337091.
  9. ↑ Marshansky V, Rubinstein JL, Grüber G (June 2014). "Eukaryotic V-ATPase: novel structural findings and functional insights". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1837 (6): 857–79. doi: 10.1016/j.bbabio.2014.01.018 . PMID   24508215.
  10. ↑ Stewart AG, Laming EM, Sobti M, Stock D (April 2014). "Rotary ATPases--dynamic molecular machines". Current Opinion in Structural Biology. 25: 40–8. doi: 10.1016/j.sbi.2013.11.013 . PMID   24878343.
  11. 1 2 Mulkidjanian AY, Makarova KS, Galperin MY, Koonin EV (November 2007). "Inventing the dynamo machine: the evolution of the F-type and V-type ATPases". Nature Reviews. Microbiology. 5 (11): 892–9. doi:10.1038/nrmicro1767. PMID   17938630.
  12. ↑ Boyer PD (1997). "The ATP synthase--a splendid molecular machine". Annual Review of Biochemistry. 66: 717–49. doi:10.1146/annurev.biochem.66.1.717. PMID   9242922.
  13. ↑ Junge W, Nelson N (2015). "ATP synthase". Annual Review of Biochemistry. 84: 631–57. doi: 10.1146/annurev-biochem-060614-034124 . PMID   25839341.
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