Noncatalytic aspartate at the exonuclease domain of proofreading DNA polymerases regulates both degradative and synthetic activities.
Proc Natl Acad Sci U S A
; 115(13): E2921-E2929, 2018 03 27.
Article
en En
| MEDLINE
| ID: mdl-29531047
Most replicative DNA polymerases (DNAPs) are endowed with a 3'-5' exonuclease activity to proofread the polymerization errors, governed by four universally conserved aspartate residues belonging to the Exo I, Exo II, and Exo III motifs. These residues coordinate the two metal ions responsible for the hydrolysis of the last phosphodiester bond of the primer strand. Structural alignment of the conserved exonuclease domain of DNAPs from families A, B, and C has allowed us to identify an additional and invariant aspartate, located between motifs Exo II and Exo III. The importance of this aspartate has been assessed by site-directed mutagenesis at the corresponding Asp121 of the family B Ï29 DNAP. Substitution of this residue by either glutamate or alanine severely impaired the catalytic efficiency of the 3'-5' exonuclease activity, both on ssDNA and dsDNA. The polymerization activity of these mutants was also affected due to a defective translocation following nucleotide incorporation. Alanine substitution for the homologous Asp90 in family A T7 DNAP showed essentially the same phenotype as Ï29 DNAP mutant D121A. This functional conservation, together with a close inspection of Ï29 DNAP/DNA complexes, led us to conclude a pivotal role for this aspartate in orchestrating the network of interactions required during internal proofreading of misinserted nucleotides.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Fagos de Bacillus
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Ácido Aspártico
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ADN Polimerasa Dirigida por ADN
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Reparación del ADN
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Replicación del ADN
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Exodesoxirribonucleasas
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Mutación
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2018
Tipo del documento:
Article
País de afiliación:
España