7lby
Bacterial cellulose synthase BcsB with polyalanine BcsA model
Structural highlights
FunctionBCSA_ECOLI Catalytic subunit of cellulose synthase. It polymerizes uridine 5'-diphosphate glucose to cellulose, which is produced as an extracellular component for mechanical and chemical protection at the onset of the stationary phase, when the cells exhibit multicellular behavior (rdar morphotype). Coexpression of cellulose and thin aggregative fimbriae (curli fimbrae or fibers) leads to a hydrophobic network with tightly packed cells embedded in a highly inert matrix that confers cohesion, elasticity and tissue-like properties to colonies (PubMed:24097954).[1] [2] Publication Abstract from PubMedCellulose is frequently found in communities of sessile bacteria called biofilms. Escherichia coli and other enterobacteriaceae modify cellulose with phosphoethanolamine (pEtN) to promote host tissue adhesion. The E. coli pEtN cellulose biosynthesis machinery contains the catalytic BcsA-B complex that synthesizes and secretes cellulose, in addition to five other subunits. The membrane-anchored periplasmic BcsG subunit catalyzes pEtN modification. Here we present the structure of the roughly 1 MDa E. coli Bcs complex, consisting of one BcsA enzyme associated with six copies of BcsB, determined by single-particle cryo-electron microscopy. BcsB homo-oligomerizes primarily through interactions between its carbohydrate-binding domains as well as intermolecular beta-sheet formation. The BcsB hexamer creates a half spiral whose open side accommodates two BcsG subunits, directly adjacent to BcsA's periplasmic channel exit. The cytosolic BcsE and BcsQ subunits associate with BcsA's regulatory PilZ domain. The macrocomplex is a fascinating example of cellulose synthase specification. Molecular organization of the E. coli cellulose synthase macrocomplex.,Acheson JF, Ho R, Goularte NF, Cegelski L, Zimmer J Nat Struct Mol Biol. 2021 Mar;28(3):310-318. doi: 10.1038/s41594-021-00569-7., Epub 2021 Mar 11. PMID:33712813[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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