Architecture of the Cellulose Synthase Outer Membrane Channel and Its Association with the Periplasmic TPR Domain.
Structure
; 27(12): 1855-1861.e3, 2019 12 03.
Article
em En
| MEDLINE
| ID: mdl-31604608
ABSTRACT
Extracellular bacterial cellulose contributes to biofilm stability and to the integrity of the bacterial cell envelope. In Gram-negative bacteria, cellulose is synthesized and secreted by a multi-component cellulose synthase complex. The BcsA subunit synthesizes cellulose and also transports the polymer across the inner membrane. Translocation across the outer membrane occurs through the BcsC porin, which extends into the periplasm via 19 tetra-tricopeptide repeats (TPR). We present the crystal structure of a truncated BcsC, encompassing the last TPR repeat and the complete outer membrane channel domain, revealing a 16-stranded, ß barrel pore architecture. The pore is blocked by an extracellular gating loop, while the extended C terminus inserts deeply into the channel and positions a conserved Trp residue near its extracellular exit. The channel is lined with hydrophilic and aromatic residues suggesting a mechanism for facilitated cellulose diffusion based on aromatic stacking and hydrogen bonding.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Celulose
/
Porinas
/
Proteínas de Escherichia coli
/
Escherichia coli
/
Repetições de Tetratricopeptídeos
/
Glucosiltransferases
Tipo de estudo:
Risk_factors_studies
Idioma:
En
Revista:
Structure
Assunto da revista:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
/
BIOTECNOLOGIA
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Estados Unidos