6TZK

Bacterial cellulose synthase outermembrane channel BcsC with terminal TPR repeat

Summary for 6TZK

• Entry DOI: 10.2210/pdb6tzk/pdb
• Descriptor: Cellulose synthase operon protein C, DODECYL-BETA-D-MALTOSIDE, HEXANE-1,6-DIOL, ... (8 entities in total)
• Functional Keywords: porin, polysaccharide secretion, cellulose synthase, membrane protein
• Biological source: Escherichia coli K-12
• Total number of polymer chains: 1
• Total formula weight: 52511.04

Authors

Acheson, J.F.,Derewenda, Z.,Zimmer, J. (deposition date: 2019-08-12, release date: 2019-10-23, Last modification date: 2024-11-13)

Primary citation

Acheson, J.F.,Derewenda, Z.S.,Zimmer, J.
Architecture of the Cellulose Synthase Outer Membrane Channel and Its Association with the Periplasmic TPR Domain.
Structure, 27:1855-, 2019

PubMed 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, β 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.

PubMed: 31604608
DOI: 10.1016/j.str.2019.09.008

Experimental method

X-RAY DIFFRACTION (1.852 Å)