Beta-galactoside transacetylase

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GAT in complex with CoA and two molecules/active site of IPTG viewed perpendicular to the molecular threefold axis of the enzyme GattrimerB IPTG.jpg
GAT in complex with CoA and two molecules/active site of IPTG viewed perpendicular to the molecular threefold axis of the enzyme

β-galactoside transacetylase is an enzyme coded for by the lacA gene of the lac operon, that transfers an acetyl group from acetyl-CoA to galactosides, glucosides and lactosides but not to the beta-galactosidase which is coded by lacZ in the lac operon of E. coli . [1] The galactoside acetyltransferase of the classical E.coli lac operon is an enzyme whose biological role remain unclear. [1] Its precise function as part of the lac operon is not understood currently. [2]

Enzyme biological molecule

Enzymes are macromolecular biological catalysts. Enzymes accelerate chemical reactions. The molecules upon which enzymes may act are called substrates and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called enzymology and a new field of pseudoenzyme analysis has recently grown up, recognising that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties.

<i>lac</i> operon Set genes encoding proteins and enzymes for lactose metabolism

The lac operon is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available through the activity of beta-galactosidase. Gene regulation of the lac operon was the first genetic regulatory mechanism to be understood clearly, so it has become a foremost example of prokaryotic gene regulation. It is often discussed in introductory molecular and cellular biology classes for this reason. This lactose metabolism system was used by François Jacob and Jacques Monod to determine how a biological cell knows which enzyme to synthesize. Their work on the lac operon won them the Nobel Prize in Physiology in 1965.

Acetyl group functional group

In organic chemistry, acetyl is a moiety, the acyl with chemical formula CH3CO. It is sometimes represented by the symbol Ac (not to be confused with the element actinium). The acetyl group contains a methyl group single-bonded to a carbonyl. The carbonyl center of an acyl radical has one nonbonded electron with which it forms a chemical bond to the remainder R of the molecule. In IUPAC nomenclature, acetyl is called ethanoyl, although this term is rarely heard. The acetyl moiety is a component of many organic compounds, including acetic acid, the neurotransmitter acetylcholine, acetyl-CoA, acetylcysteine, acetaminophen (also known as paracetamol), and acetylsalicylic acid (better known as aspirin).

Contents

The kinetics of the enzyme were delineated in 1995. [3]

The enzyme's cellular role may be to detoxify non-metabolizable pyranosides by acetylating them and preventing their reentry into the cell. [4]

See also

Related Research Articles

Pyruvate dehydrogenase complex (PDC) is a complex of three enzymes that converts pyruvate into acetyl-CoA by a process called pyruvate decarboxylation. Acetyl-CoA may then be used in the citric acid cycle to carry out cellular respiration, and this complex links the glycolysis metabolic pathway to the citric acid cycle. Pyruvate decarboxylation is also known as the "pyruvate dehydrogenase reaction" because it also involves the oxidation of pyruvate.

Isopropyl β-<small>D</small>-1-thiogalactopyranoside chemical compound

Isopropyl β-D-1-thiogalactopyranoside (IPTG) is a molecular biology reagent. This compound is a molecular mimic of allolactose, a lactose metabolite that triggers transcription of the lac operon, and it is therefore used to induce protein expression where the gene is under the control of the lac operator.

Chloramphenicol acetyltransferase InterPro Family

Chloramphenicol acetyltransferase is a bacterial enzyme that detoxifies the antibiotic chloramphenicol and is responsible for chloramphenicol resistance in bacteria. This enzyme covalently attaches an acetyl group from acetyl-CoA to chloramphenicol, which prevents chloramphenicol from binding to ribosomes. A histidine residue, located in the C-terminal section of the enzyme, plays a central role in its catalytic mechanism.

Dihydrolipoyl transacetylase protein-coding gene in the species Homo sapiens

Dihydrolipoyl transacetylase is an enzyme component of the multienzyme pyruvate dehydrogenase complex. The pyruvate dehydrogenase complex is responsible for the pyruvate decarboxylation step that links glycolysis to the citric acid cycle. This involves the transformation of pyruvate from glycolysis into acetyl-CoA which is then used in the citric acid cycle to carry out cellular respiration.

Aralkylamine <i>N</i>-acetyltransferase

Aralkylamine N-acetyltransferase (AANAT), also known as arylalkylamine N-acetyltransferase or serotonin N-acetyltransferase (SNAT), is an enzyme that is involved in the day/night rhythmic production of melatonin, by modification of serotonin. It is in humans encoded by the ~2.5 kb AANAT gene containing four exons, located on chromosome 17q25. The gene is translated into a 23 kDa large enzyme. It is well conserved through evolution and the human form of the protein is 80% identical to sheep and rat AANAT. It is an acetyl-CoA-dependent enzyme of the GCN5-related family of N-acetyltransferases (GNATs). It may contribute to multifactorial genetic diseases such as altered behavior in sleep/wake cycle and research is on-going with the aim of developing drugs that regulate AANAT function.

Phosphogluconate dehydrogenase

6-Phosphogluconate dehydrogenase (6PGD) is an enzyme in the pentose phosphate pathway. It forms ribulose 5-phosphate from 6-phosphogluconate.

Thiolase InterPro Family

Thiolases, also known as acetyl-coenzyme A acetyltransferases (ACAT), are enzymes which convert two units of acetyl-CoA to acetoacetyl CoA in the mevalonate pathway.

Amine oxidase (copper-containing) enzyme

Amine oxidase (copper-containing) (AOC) (EC 1.4.3.21 and EC 1.4.3.22; formerly EC 1.4.3.6) is a family of amine oxidase enzymes which includes both primary-amine oxidase and diamine oxidase; these enzymes catalyze the oxidation of a wide range of biogenic amines including many neurotransmitters, histamine and xenobiotic amines. They act as a disulphide-linked homodimer. They catalyse the oxidation of primary amines to aldehydes, with the subsequent release of ammonia and hydrogen peroxide, which requires one copper ion per subunit and topaquinone as cofactor:

Indole-3-glycerol-phosphate synthase

In enzymology, an indole-3-glycerol-phosphate synthase (IGPS) (EC 4.1.1.48) is an enzyme that catalyzes the chemical reaction

In enzymology, a [acyl-carrier-protein] S-acetyltransferase is an enzyme that catalyzes the chemical reaction

In enzymology, an arylamine N-acetyltransferase is an enzyme that catalyzes the chemical reaction

In enzymology, a glucosamine-phosphate N-acetyltransferase is an enzyme that catalyzes the chemical reaction

In enzymology, a glutamate N-acetyltransferase (EC 2.3.1.35) is an enzyme that catalyzes the chemical reaction

In enzymology, a homoserine O-acetyltransferase is an enzyme that catalyzes the chemical reaction

In enzymology, a maltose O-acetyltransferase is an enzyme that catalyzes the chemical reaction

In enzymology, a N6-hydroxylysine O-acetyltransferase (EC 2.3.1.102) is an enzyme that catalyzes the chemical reaction

Serine O-acetyltransferase

In enzymology, a serine O-acetyltransferase is an enzyme that catalyzes the chemical reaction

Glycoside hydrolase family 24

In molecular biology, glycoside hydrolase family 24 is a family of glycoside hydrolases.

Glycoside hydrolase family 36

In molecular biology, glycoside hydrolase family 36 is a family of glycoside hydrolases.

References

  1. 1 2 Wang XG; Olsen LR; Roderick SL. (April 2002). "Structure of the lac operon galactoside acetyltransferase". Structure. 10 (4): 581–8. doi:10.1016/S0969-2126(02)00741-4. PMID   11937062.
  2. ↑ Roderick SL. (June 2005). "The lac operon galactoside acetyltransferase". Comptes Rendus Biologies. 328 (6): 568–75. doi:10.1016/j.crvi.2005.03.005. PMID   15950163.
  3. ↑ A. Lewendon; J. Ellis; W.V. Shaw (1995). "Structural and Mechanistic Studies of Galactoside Acetyltransferase, the Escherichia coli LacA Gene Product". J. Biol. Chem. 270 (44): 26326–31. doi:10.1074/jbc.270.44.26326. PMID   7592843.
  4. ↑ Wang, XG; Olsen, LR; Roderick, SL (2002). "Structure of the lac operon galactoside acetyltransferase". Structure. 10 (4): 581–8. doi:10.1016/S0969-2126(02)00741-4. PMID   11937062.

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The Enzyme Commission number is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze. As a system of enzyme nomenclature, every EC number is associated with a recommended name for the respective enzyme.


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