Two-way traffic of glycoside hydrolase family 18 processive chitinases on crystalline chitin.
Nat Commun
; 5: 3975, 2014 Jun 04.
Article
em En
| MEDLINE
| ID: mdl-24894873
ABSTRACT
Processivity refers to the ability of synthesizing, modifying and degrading enzymes to catalyse multiple successive cycles of reaction with polymeric substrates without disengaging from the substrates. Since biomass polysaccharides, such as chitin and cellulose, often form recalcitrant crystalline regions, their degradation is highly dependent on the processivity of degrading enzymes. Here we employ high-speed atomic force microscopy to directly visualize the movement of two processive glycoside hydrolase family 18 chitinases (ChiA and ChiB) from the chitinolytic bacterium Serratia marcescens on crystalline ß-chitin. The half-life of processive movement and the velocity of ChiA are larger than those of ChiB, suggesting that asymmetric subsite architecture determines both the direction and the magnitude of processive degradation of crystalline polysaccharides. The directions of processive movements of ChiA and ChiB are observed to be opposite. The molecular mechanism of the two-way traffic is discussed, including a comparison with the processive cellobiohydrolases of the cellulolytic system.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Serratia marcescens
/
Proteínas de Bactérias
/
Quitina
/
Quitinases
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article