Adenylyl transferase

ATP interacts with sulfate ion (SO ) to form adenosine 5-phosphosulfate (APS) in a reaction mediated by the enzyme ATP sulfate adenylyl transferase. 

DIETHYL PYROCARBONATE DEPHOSPHO-CoA KINASE Dephospho-CoA pyrophosphorylase, PANTETHEINE-RHOSRHATE ADENYLYL-TRANSFERASE DEPOLARIZATION ACTION ROTENTIAL HYPERROLARIZATION DEPOLYMERIZATION PROCESSIVITY... 

The adenylation and phosphorolysis reactions are catalyzed by the same enzyme, adenylyl transferase. Sequence analysis indicates that this adenylyl transferase comprises two homologous halves, suggesting that one half catalyzes the adenylation reaction and the other half the phospholytic de-adenylation reaction. What determines whether an AMP unit is added or removed The specificity of adenylyl transferase is controlled by a regulatory protein (designated P or Pjj), a trimeric protein that can exist in two forms, P and Pq (Figure 24.27). The complex of P and adenylyl transferase catalyzes the attachment of an AMP unit to glutamine synthetase, which reduces its activity. Conversely, the complex of Pj) and adenylyl transferase removes AMP from the adenylylated enzyme. 

Figure 24.26. Regulation by Adenylation. (A) A specific tyrosine residue in each subunit in glutamine synthetase is modified by adenylation. (B) Adenylation of tyrosine is catalyzed by a complex of adenylyl transferase (AT) and one form of a regulatory protein (P ). The same enzyme catalyzes deadenylation when it is complexed with the other form (Pq) of the regulatory protein.

Figure 24.28. A Higher Level in the Regulatory Cascade of Glutamine Synthetase. and Pq the regulatory proteins that control the specificity of adenylyl transferase, are interconvertible. P is converted into Pq by uridylylation, which is reversed by hydrolysis. The enzymes catalyzing these reactions are regulated by the concentrations of metabolic intermediates.

Mutations in ATPS (sulfate adenylyl transferase, EC 2.7.7.4) in the yeast Schizosaccharomyces pombe resulted in increased selenate tolerance [207]. The selenate resistant phenotype of these mutants was correlated with low sulfate uptake capacity and low ATPS activity. 

The Wlds mutation is dominant and has been mapped to the distal end of chromosome 4 (Lyon et al., 1993), where there is an 85-kb tandem triplication that results in the production of an abnormal fusion protein (Conforti et al., 2000). This fusion protein contains the intact enzyme nicotinamide mononucleotide adenylyl transferase (NMNAT), which functions in the synthetic pathway for nicotinamide adenine dinucleotide (NAD+), as well as the ubiquitination factor E4b (UbE4b). 

ADP-Rihosyl transferase (adenylyl transferase, polynucleotide, from human placenta)... 

Adenylylation renders the catalytic site of the enzyme inactive. Adenylylation and deadenylylation involve a complex series of regulatory cascades. Figure 20.9 shows regulatory mechanisms of the E. coli enzyme. Both processes are catalyzed by the same enzyme-a complex of adenylyl transferase (AT) and a regulatory protein, PIT The form of PII determines whether the AT-PII complex catalyzes adenylylation or deadenylylation. 

The enzyme glutamine synthetase is regulated covalently and allosterically. The covalent modification is an adenylylation catalyzed by the enzyme adenylyl transferase (AT). AT catalyzes the reaction in which a specific tyrosine residue in glutamine synthetase reacts with ATP to form an ester between the phenolic hydroxyl group and the phosphate of the resultant AMP. That tyrosine residue lies very close to a catalytic site. Adenylylation inactivates the adjacent catalytic site. A glutamine synthetase molecule with all 12 sites adenylylated is completely inactive, whereas partial adenylylation yields partial inactivation. 

Deoxygentamicin C2 was synthesized by Daniels and found, as expected, to be active against resistant bacteria producing the adenylyl transferase. 

Umezawa and coworkers first described streptomycin adenylyl transferase in E. coli K12 ML1629 carrying an R factor resistant to streptomycin, kanamycins A, B, and C, paromamine, neamine, paromomycin, neomycin, chloramphenicol, and tetracycline, and confirmed that the inactivated product is adenylylstreptomycin. 

Davies and coworkers found that streptomycin adenylyl transferase also adenylylates spectinomycin and actinamine. Because of the stereochemical resemblance between actinamine and the o threo methyl-amino alcohol moiety in streptomycin, the site of adenylylation was considered to be that shown by the arrow in formula 15. 

Kawabe and Mitsuhashi reported that the streptomycin-inactivating enzyme in staphylococci of medium resistance seems to be of the streptomycin adenylyl transferase type, because the C-adenosine residue... 

Why is it important that adenylyl transferase not carry out adenylylation and dead-enylylation of glutamine synthetase at the same time ... 

Schweiger M, Hennig K, Lerner F et al. Characterization of recombinant human nicotinamide mononucleotide adenylyl transferase (NMNAT), a nuclear enzyme essential for NAD synthesis. FEBS Lett 2001 492 95-100. 

Nicotinamide—mononucleotide adenylyl transferase Amine oxidase (outer membrane),... 

ADP-Ribosyl transferase (adenylyl transferase, polynueleotide, from human plaeenta) [9026-30-6] Mr 115,000 [EC 2.4.2.30]. Purify the transferase by making an affinity absorbent for ADP-ribosyltransferase by coupling 3-aminobenzamide to Sepharose 4B. [Burtscher et al. Anal Biochem 152 285 19861 ... 

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