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Structural basis for synthase activation and cellulose modification in the E. coli Type II Bcs secretion system.
- Source :
-
Nature communications [Nat Commun] 2024 Oct 11; Vol. 15 (1), pp. 8799. Date of Electronic Publication: 2024 Oct 11. - Publication Year :
- 2024
-
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 BcsE <subscript>2</subscript> R <subscript>2</subscript> Q <subscript>2</subscript> 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.<br /> (© 2024. The Author(s).)
- Subjects :
- Ethanolamines metabolism
Ethanolamines chemistry
Bacterial Secretion Systems metabolism
Bacterial Secretion Systems genetics
Cellulose metabolism
Escherichia coli metabolism
Escherichia coli genetics
Escherichia coli Proteins metabolism
Escherichia coli Proteins genetics
Escherichia coli Proteins chemistry
Glucosyltransferases metabolism
Glucosyltransferases genetics
Cyclic GMP metabolism
Cyclic GMP analogs & derivatives
Cryoelectron Microscopy
Subjects
Details
- Language :
- English
- ISSN :
- 2041-1723
- Volume :
- 15
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Nature communications
- Publication Type :
- Academic Journal
- Accession number :
- 39394223
- Full Text :
- https://doi.org/10.1038/s41467-024-53113-8