Structural and biochemical analyses of the Streptococcus pneumonia L,D-carboxypeptidase DacB.
Acta Crystallogr D Biol Crystallogr
; 71(Pt 2): 283-92, 2015 Feb.
Article
em En
| MEDLINE
| ID: mdl-25664738
ABSTRACT
The L,D-carboxypeptidase DacB plays a key role in the remodelling of Streptococcus pneumoniae peptidoglycan during cell division. In order to decipher its substrate-binding properties and catalytic mechanism, the 1.71â
Å resolution crystal structure of DacB from S. pneumoniae TIGR4 is reported. Structural analyses in combination with comparisons with the recently reported structures of DacB from S. pneumoniae D39 and R6 clearly demonstrate that DacB adopts a zinc-dependent carboxypeptidase fold and belongs to the metallopeptidase M15B subfamily. In addition, enzymatic activity assays further confirm that DacB indeed acts as an L,D-carboxypeptidase towards the tetrapeptide L-Ala-D-iGln-L-Lys-D-Ala of the peptidoglycan stem, with Km and kcat values of 2.84 ± 0.37â
mM and 91.49 ± 0.05â
s(-1), respectively. Subsequent molecular docking and site-directed mutagenesis enable the assignment of the key residues that bind to the tetrapeptide. Altogether, these findings provide structural insights into substrate recognition in the metallopeptidase M15B subfamily.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Streptococcus pneumoniae
/
Carboxipeptidases
Limite:
Humans
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article