Engineering and directed evolution of a Ca2+ binding site A-deficient AprE mutant reveal an essential contribution of the loop Leu75-Leu82 to enzyme activity.
J Biomed Biotechnol
; 2009: 201075, 2009.
Article
em En
| MEDLINE
| ID: mdl-19710937
ABSTRACT
An aprE mutant from B. subtilis 168 lacking the connecting loop Leu(75)-Leu(82) which is predicted to encode a Ca(2+) binding site was constructed. Expression of the mutant gene (aprEDeltaLeu(75)-Leu(82)) produced B. subtilis colonies lacking protease activity. Intrinsic fluorescence analysis revealed spectral differences between wild-type AprE and AprEDeltaL(75)-L(82). An AprEDeltaL(75)-L(82) variant with reestablished enzyme activity was selected by directed evolution. The novel mutations Thr(66)Met/Gly(102)Asp located in positions which are predicted to be important for catalytic activity were identified in this variant. Although these mutations restored hydrolysis, they had no effect with respect to thermal inactivation of AprEDeltaL(75)-L(82) T(66)M G(102)D. These results support the proposal that in addition to function as a calcium binding site, the loop that connects beta-sheet e3 with alpha-helix c plays a structural role on enzyme activity of AprE from B. subtilis 168.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Membrana Transportadoras
/
Proteínas de Bactérias
/
Cálcio
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Mutagênese Sítio-Dirigida
/
Evolução Molecular Direcionada
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article