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9FNN

Cryo-EM structure of the c-di-GMP-saturated 'crown'less Bcs macrocomplex for cellulose secretion in E. coli

Summary for 9FNN
Entry DOI10.2210/pdb9fnn/pdb
Related9FMT 9FMZ
EMDB information50567 50581 50584 50599
DescriptorCellulose synthase catalytic subunit [UDP-forming], MAGNESIUM ION, Cyclic di-GMP-binding protein, ... (10 entities in total)
Functional Keywordsbacterial cellulose secretion, membrane protein
Biological sourceEscherichia coli
More
Total number of polymer chains15
Total formula weight783240.40
Authors
Anso, I.,Krasteva, P.V. (deposition date: 2024-06-10, release date: 2024-10-16, Last modification date: 2024-10-23)
Primary citationAnso, I.,Zouhir, S.,Sana, T.G.,Krasteva, P.V.
Structural basis for synthase activation and cellulose modification in the E. coli Type II Bcs secretion system.
Nat Commun, 15:8799-8799, 2024
Cited by
PubMed Abstract: Bacterial cellulosic polymers constitute a prevalent class of biofilm matrix exopolysaccharides that are synthesized by several types of bacterial cellulose secretion (Bcs) systems, which include conserved cyclic diguanylate (c-di-GMP)-dependent cellulose synthase modules together with diverse accessory subunits. In E. coli, the biogenesis of phosphoethanolamine (pEtN)-modified cellulose relies on the BcsRQABEFG macrocomplex, encompassing inner-membrane and cytosolic subunits, and an outer membrane porin, BcsC. Here, we use cryogenic electron microscopy to shed light on the molecular mechanisms of BcsA-dependent recruitment and stabilization of a trimeric BcsG pEtN-transferase for polymer modification, and a dimeric BcsF-dependent recruitment of an otherwise cytosolic BcsERQ regulatory complex. We further demonstrate that BcsE, a secondary c-di-GMP sensor, can remain dinucleotide-bound and retain the essential-for-secretion BcsRQ partners onto the synthase even in the absence of direct c-di-GMP-synthase complexation, likely lowering the threshold for c-di-GMP-dependent synthase activation. Such activation-by-proxy mechanism could allow Bcs secretion system activity even in the absence of substantial intracellular c-di-GMP increase, and is reminiscent of other widespread synthase-dependent polysaccharide secretion systems where dinucleotide sensing and/or synthase stabilization are carried out by key co-polymerase subunits.
PubMed: 39394223
DOI: 10.1038/s41467-024-53113-8
PDB entries with the same primary citation
Experimental method
ELECTRON MICROSCOPY (2.85 Å)
Structure validation

239149

数据于2025-07-23公开中

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