1Z3A

Crystal structure of tRNA adenosine deaminase TadA from Escherichia coli

Summary for 1Z3A

• Entry DOI: 10.2210/pdb1z3a/pdb
• Descriptor: tRNA-specific adenosine deaminase, ZINC ION (3 entities in total)
• Functional Keywords: trna adenosine deaminase, dimer, zinc, metalloenzyme, structural genomics, psi, protein structure initiative, new york sgx research center for structural genomics, nysgxrc, hydrolase
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 37850.31

Authors

Malashkevich, V.,Kim, J.,Lisbin, M.,Almo, S.C.,Burley, S.K.,New York SGX Research Center for Structural Genomics (NYSGXRC) (deposition date: 2005-03-10, release date: 2006-02-21, Last modification date: 2024-04-03)

Primary citation

Kim, J.,Malashkevich, V.,Roday, S.,Lisbin, M.,Schramm, V.L.,Almo, S.C.
Structural and kinetic characterization of Escherichia coli TadA, the wobble-specific tRNA deaminase.
Biochemistry, 45:6407-6416, 2006

PubMed Abstract: The essential tRNA-specific adenosine deaminase catalyzes the deamination of adenosine to inosine at the wobble position of tRNAs. This modification allows for a single tRNA species to recognize multiple synonymous codons containing A, C, or U in the last (3'-most) position and ensures that all sense codons are appropriately decoded. We report the first combined structural and kinetic characterization of a wobble-specific deaminase. The structure of the Escherichia coli enzyme clearly defines the dimer interface and the coordination of the catalytically essential zinc ion. The structure also identifies the nucleophilic water and highlights residues near the catalytic zinc likely to be involved in recognition and catalysis of polymeric RNA substrates. A minimal 19 nucleotide RNA stem substrate has permitted the first steady-state kinetic characterization of this enzyme (k(cat) = 13 +/- 1 min(-)(1) and K(M) = 0.83 +/- 0.22 microM). A continuous coupled assay was developed to follow the reaction at high concentrations of polynucleotide substrates (>10 microM). This work begins to define the chemical and structural determinants responsible for catalysis and substrate recognition and lays the foundation for detailed mechanistic analysis of this essential enzyme.

PubMed: 16700551
DOI: 10.1021/bi0522394

Experimental method

X-RAY DIFFRACTION (2.03 Å)