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Título
BcsA and BcsB form the catalytically active core of bacterial cellulose synthase sufficient for in vitro cellulose synthesis
Autor
Facultad/Centro
Área de conocimiento
Título de la revista
Proceedings of the National Academy of Sciences
Número de la revista
44
Cita Bibliográfica
Omadjela, O., Narahari, A., Strumillo, J., Mélida, H., Mazur, O., Bulone, V., & Zimmer, J. (2013). BcsA and BcsB form the catalytically active core of bacterial cellulose synthase sufficient for in vitro cellulose synthesis. Proceedings of the National Academy of Sciences of the United States of America, 110(44), 17856-17861. https://doi.org/10.1073/PNAS.1314063110
Editorial
National Academy of Sciences of the United States of America
Fecha
2013
ISSN
0027-8424
Resumen
[EN] Cellulose is a linear extracellular polysaccharide. It is synthesized
by membrane-embedded glycosyltransferases that processively
polymerize UDP-activated glucose. Polymer synthesis is coupled to
membrane translocation through a channel formed by the cellulose
synthase. Although eukaryotic cellulose synthases function in
macromolecular complexes containing several different enzyme
isoforms, prokaryotic synthases associate with additional subunits
to bridge the periplasm and the outer membrane. In bacteria,
cellulose synthesis and translocation is catalyzed by the inner
membrane-associated bacterial cellulose synthase (Bcs)A and BcsB
subunits. Similar to alginate and poly-β-1,6 N-acetylglucosamine,
bacterial cellulose is implicated in the formation of sessile bacterial
communities, termed biofilms, and its synthesis is likewise stimulated
by cyclic-di-GMP. Biochemical studies of exopolysaccharide
synthesis are hampered by difficulties in purifying and reconstituting
functional enzymes. We demonstrate robust in vitro cellulose
synthesis reconstituted from purified BcsA and BcsB proteins from
Rhodobacter sphaeroides. Although BcsA is the catalytically active
subunit, the membrane-anchored BcsB subunit is essential for catalysis.
The purified BcsA-B complex produces cellulose chains of
a degree of polymerization in the range 200–300. Catalytic activity
critically depends on the presence of the allosteric activator cyclicdi-
GMP, but is independent of lipid-linked reactants. Our data reveal
feedback inhibition of cellulose synthase by UDP but not by
the accumulating cellulose polymer and highlight the strict substrate
specificity of cellulose synthase for UDP-glucose. A truncation
analysis of BcsB localizes the region required for activity of
BcsA within its C-terminal membrane-associated domain. The reconstituted
reaction provides a foundation for the synthesis of biofilm
exopolysaccharides, as well as its activation by cyclic-di-GMP.
Materia
Palabras clave
Peer review
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