In enzymology, a sulfate adenylyltransferase () is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

that catalyzes the

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

:ATP + sulfate

\rightleftharpoons

pyrophosphate + adenylyl sulfate Thus, the two substrates of this enzyme are ATP and

sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...

, whereas its two

products Product may refer to: Business * Product (business), an item that serves as a solution to a specific consumer problem. * Product (project management), a deliverable or set of deliverables that contribute to a business solution Mathematics * Produ ...

are

pyrophosphate In chemistry, pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a P–O–P linkage. A number of pyrophosphate salts exist, such as disodium pyrophosphate (Na2H2P2O7) and tetrasodium pyrophosphate (Na4P2O7), among othe ...

and

adenylyl sulfate Adenosine monophosphate (AMP), also known as 5'-adenylic acid, is a nucleotide. AMP consists of a phosphate group, the sugar ribose, and the nucleobase adenine; it is an ester of phosphoric acid and the nucleoside adenosine. As a substituent it t ...

. This enzyme belongs to the family of

transferase A transferase is any one of a class of enzymes that catalyse the transfer of specific functional groups (e.g. a methyl or glycosyl group) from one molecule (called the donor) to another (called the acceptor). They are involved in hundreds of ...

s, specifically those transferring phosphorus-containing

nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules wi ...

groups (

nucleotidyltransferase Nucleotidyltransferases are transferase enzymes of phosphorus-containing groups, e.g., substituents of nucleotidylic acids or simply nucleoside monophosphates. The general reaction of transferring a nucleoside monophosphate moiety from A to B, can ...

s). The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ...

of this enzyme class is ATP:sulfate adenylyltransferase. Other names in common use include adenosine-5'-triphosphate sulfurylase, adenosinetriphosphate sulfurylase, adenylylsulfate pyrophosphorylase, ATP sulfurylase, ATP-sulfurylase, and sulfurylase. This enzyme participates in 3

metabolic pathways In biochemistry, a metabolic pathway is a linked series of chemical reactions occurring within a cell. The reactants, products, and intermediates of an enzymatic reaction are known as metabolites, which are modified by a sequence of chemical re ...

purine metabolism Purine metabolism refers to the metabolic pathways to synthesize and break down purines that are present in many organisms. Biosynthesis Purines are biologically synthesized as nucleotides and in particular as ribotides, i.e. bases attached to r ...

, selenoamino acid metabolism, and

sulfur metabolism Sulfur is metabolized by all organisms, from bacteria and archaea to plants and animals. Sulfur is reduced or oxidized by organisms in a variety of forms. The element is present in proteins, sulfate esters of polysaccharides, steroids, ph ...

. Some sulfate adenylyltransferases are part of a bifunctional polypeptide chain associated with adenosyl phosphosulfate (APS) kinase. Both

s are required for PAPS (phosphoadenosine-phosphosulfate) synthesis from

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemist ...

sulfate. Within the cell Sulfate adenylyltransferase plays a key role in both assimilatory sulfur reduction and dissimilatory sulfur oxidation and reduction (DSR) and participates in the biogeochemically relevant sulfur cycle. In dissimilatory sulfate reduction the SAT enzyme, acts as the first priming step in the reduction converting

(+6) to Adenosine 5'-phosphosulfate (APS) via adenylation at the cost of an ATP. If the organisms participating in the DSR pathway possess the full suite of genes necessary, APS can then be further stepwise reduced to sulfite(+4) and then sulfide (-2). Conversely in the process of dissimilatory sulfate oxidation, pyrophosphate combines with APS in a sulfate adenylyltransferase catalyzed reaction to form

. In either direction in which the Sulfate adenylyltransferase (reduction or oxidation) proceeds along DSR in bacterial cells, the associated pathways are participating in cellular respiration necessary for the growth of the organism.

Structural studies

As of late 2007, 18

structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

have been solved for this class of enzymes, with PDB accession codes , , , , , , , , , , , , , , , , , and . In yeast other fungi and bacteria participating in assimilatory sulfate reduction, the sulfate adenylyltransferase is in the form a of a homohexamer. Its shape is that of a homotetramer in plants. In Saccharomyces cerevisiae sulfate adenylyltransferase is composed of four domains. Domain I features the N-terminus with beta-barrels similar to pyruvate kinase. A right handed alpha/beta fold makes of the shape of Domain II, and it also contains the active site and substrate-binding pocket. Domain III is composed of a region linking the terminal domain to Domain I & II. Domain IV contains the C-terminus of the protein and forms a typical alpha/beta-fold. The active site of Sulfate adenylyltransferase is composed mostly of portions of the Domain II specifically, H9, S9, S10, S12, and the conserved RNP-Loop and GRD-Loop. The active site is located in the center of the Sulfate adenylyltransferase above the Domain II between the other domains I & II. The core of the groove in which the active site is located is mostly composed of hydrophobic residues, but towards the outside of the groove are positive and hydrophilic residues necessary for substrate binding.

Applications

ATP sulfurylase is one of the enzymes used in

pyrosequencing Pyrosequencing is a method of DNA sequencing (determining the order of nucleotides in DNA) based on the "sequencing by synthesis" principle, in which the sequencing is performed by detecting the nucleotide incorporated by a DNA polymerase. Pyroseq ...

Structural studies

Applications

References

Further reading