Crystallographic snapshot of cellulose synthesis and membrane translocation


Cellulose, the most abundant biological macromolecule, is an extracellular, linear polymer of glucose molecules. It represents an essential component of plant cell walls but is also found in algae and bacteria. In bacteria, cellulose production frequently correlates with the formation of biofilms, a sessile, multicellular growth form. Cellulose synthesis and transport across the inner bacterial membrane is mediated by a complex of the membrane-integrated catalytic BcsA subunit and the membrane-anchored, periplasmic BcsB protein. Here we present the crystal structure of a complex of BcsA and BcsB from Rhodobacter sphaeroides containing a translocating polysaccharide. The structure of the BcsA–BcsB translocation intermediate reveals the architecture of the cellulose synthase, demonstrates how BcsA forms a cellulose-conducting channel, and suggests a model for the coupling of cellulose synthesis and translocation in which the nascent polysaccharide is extended by one glucose molecule at a time.

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Figure 1: Architecture of the BcsA–BcsB complex.
Figure 2: Organization of BcsA’s catalytic site and PilZ domain.
Figure 3: The membrane-integrated domain of BcsA–BcsB.
Figure 4: Organization of the periplasmic domain.
Figure 5: Proposed model for cellulose synthesis and translocation.

Accession codes

Primary accessions

Protein Data Bank

Data deposits

The atomic coordinates and structure factors have been deposited in the Protein Data Bank under accession number 4HG6.


  1. 1

    Somerville, C. Cellulose synthesis in higher plants. Annu. Rev. Cell Dev. Biol. 22, 53–78 (2006)

    CAS  Article  Google Scholar 

  2. 2

    Merzendorfer, H. Insect chitin synthases: a review. J. Comp. Physiol. B 176, 1–15 (2006)

    CAS  Article  Google Scholar 

  3. 3

    Hubbard, C., McNamara, J. T., Azumaya, C., Patel, M. S. & Zimmer, J. The hyaluronan synthase catalyzes the synthesis and membrane translocation of hyaluronan. J. Mol. Biol. 418, 21–31 (2012)

    CAS  Article  Google Scholar 

  4. 4

    Nishiyama, Y., Langan, P. & Chanzy, H. Crystal structure and hydrogen-bonding system in cellulose Iβ from synchrotron X-ray and neutron fiber diffraction. J. Am. Chem. Soc. 124, 9074–9082 (2002)

    CAS  Article  Google Scholar 

  5. 5

    Matthysse, A. G., Thomas, D. L. & White, A. R. Mechanism of cellulose synthesis in Agrobacterium tumefaciens. J. Bacteriol. 177, 1076–1081 (1995)

    CAS  Article  Google Scholar 

  6. 6

    Bureau, T. E. & Brown, R. M. In vitro synthesis of cellulose II from a cytoplasmic membrane fraction of Acetobacter xylinum. Proc. Natl Acad. Sci. USA 84, 6985–6989 (1987)

    ADS  CAS  Article  Google Scholar 

  7. 7

    Grimson, M. J., Haigler, C. H. & Blanton, R. L. Cellulose microfibrils, cell motility, and plasma membrane protein organization change in parallel during culmination in Dictyostelium discoideum. J. Cell Sci. 109, 3079–3087 (1996)

    CAS  PubMed  Google Scholar 

  8. 8

    Kimura, S. & Itoh, T. New cellulose synthesizing complexes (terminal complexes) involved in animal cellulose biosynthesis in the tunicate Metandrocarpa uedai. Protoplasma 194, 151–163 (1996)

    CAS  Article  Google Scholar 

  9. 9

    Aloni, Y., Delmer, D. P. & Benziman, M. Achievement of high rates of in vitro synthesis of 1,4-beta-d-glucan: activation by cooperative interaction of the Acetobacter xylinum enzyme system with GTP, polyethylene glycol, and a protein factor. Proc. Natl Acad. Sci. USA 79, 6448–6452 (1982)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Lairson, L. L., Henrissat, B., Davies, G. J. & Withers, S. G. Glycosyltransferases: structures, functions, and mechanisms. Annu. Rev. Biochem. 77, 521–555 (2008)

    CAS  Article  Google Scholar 

  11. 11

    Römling, U. Molecular biology of cellulose production in bacteria. Res. Microbiol. 153, 205–212 (2002)

    Article  Google Scholar 

  12. 12

    Cantarel, B. L. et al. The Carbohydrate-Active EnZymes database (CAZy): an expert resource for glycogenomics. Nucleic Acids Res. 37, D233–D238 (2009)

    CAS  Article  Google Scholar 

  13. 13

    Standal, R. et al. A new gene required for cellulose production and a gene encoding cellulolytic activity in Acetobacter xylinum are colocalized with the bcs operon. J. Bacteriol. 176, 665–672 (1994)

    CAS  Article  Google Scholar 

  14. 14

    Saxena, I. M., Kudlicka, K., Okuda, K. & Brown, R. M. Characterization of genes in the cellulose-synthesizing operon (acs operon) of Acetobacter xylinum: implications for cellulose crystallization. J. Bacteriol. 176, 5735–5752 (1994)

    CAS  Article  Google Scholar 

  15. 15

    Hu, S. Q. et al. Structure of bacterial cellulose synthase subunit D octamer with four inner passageways. Proc. Natl Acad. Sci. USA 107, 17957–17961 (2010)

    ADS  CAS  Article  Google Scholar 

  16. 16

    Jahn, C. E., Selimi, D. A., Barak, J. D. & Charkowski, A. O. The Dickeya dadantii biofilm matrix consists of cellulose nanofibres, and is an emergent property dependent upon the type III secretion system and the cellulose synthesis operon. Microbiology 157, 2733–2744 (2011)

    CAS  Article  Google Scholar 

  17. 17

    Stewart, P. S. & Costerton, J. W. Antibiotic resistance of bacteria in biofilms. Lancet 358, 135–138 (2001)

    CAS  Article  Google Scholar 

  18. 18

    Amikam, D. & Galperin, M. Y. PilZ domain is part of the bacterial c-di-GMP binding protein. Bioinformatics 22, 3–6 (2006)

    CAS  Article  Google Scholar 

  19. 19

    Römling, U., Gomelsky, M. & Galperin, M. Y. C-di-GMP: the dawning of a novel bacterial signalling system. Mol. Microbiol. 57, 629–639 (2005)

    Article  Google Scholar 

  20. 20

    Ross, P. et al. Regulation of cellulose synthesis in Acetobacter xylinum by cyclic diguanylic acid. Nature 325, 279–281 (1987)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Koyama, M., Helbert, W., Imai, T., Sugiyama, J. & Henrissat, B. Parallel-up structure evidences the molecular directionality during biosynthesis of bacterial cellulose. Proc. Natl Acad. Sci. USA 94, 9091–9095 (1997)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Lai-Kee-Him, J. et al. In vitro versus in vivo cellulose microfibrils from plant primary wall synthases: structural differences. J. Biol. Chem. 277, 36931–36939 (2002)

    CAS  Article  Google Scholar 

  23. 23

    Charnock, S. J. & Davies, G. J. Structure of the nucleotide-diphospho-sugar transferase, SpsA from Bacillus subtilis, in native and nucleotide-complexed forms. Biochemistry 38, 6380–6385 (1999)

    CAS  Article  Google Scholar 

  24. 24

    Weigel, P. H. & Deangelis, P. L. Hyaluronan synthases: a decade-plus of novel glycosyltransferases. J. Biol. Chem. 282, 36777–36781 (2007)

    CAS  Article  Google Scholar 

  25. 25

    Kozmon, S. & Tvaroska, I. Catalytic mechanism of glycosyltransferases: hybrid quantum mechanical/molecular mechanical study of the inverting N-acetylglucosaminyltransferase I. J. Am. Chem. Soc. 128, 16921–16927 (2006)

    CAS  Article  Google Scholar 

  26. 26

    Kubota, T. et al. Structural basis of carbohydrate transfer activity by human UDP-GalNAc: polypeptide α-N-acetylgalactosaminyltransferase (pp-GalNAc-T10). J. Mol. Biol. 359, 708–727 (2006)

    CAS  Article  Google Scholar 

  27. 27

    Daras, G. et al. The thanatos mutation in Arabidopsis thaliana cellulose synthase 3 (AtCesA3) has a dominant-negative effect on cellulose synthesis and plant growth. New Phytol. 184, 114–126 (2009)

    CAS  Article  Google Scholar 

  28. 28

    Benach, J. et al. The structural basis of cyclic diguanylate signal transduction by PilZ domains. EMBO J. 26, 5153–5166 (2007)

    CAS  Article  Google Scholar 

  29. 29

    Scheible, W. R., Eshed, R., Richmond, T., Delmer, D. & Somerville, C. Modifications of cellulose synthase confer resistance to isoxaben and thiazolidinone herbicides in Arabidopsis Ixr1 mutants. Proc. Natl Acad. Sci. USA 98, 10079–10084 (2001)

    ADS  CAS  Article  Google Scholar 

  30. 30

    Harris, D. M. et al. Cellulose microfibril crystallinity is reduced by mutating C-terminal transmembrane region residues CESA1A903V and CESA3T942I of cellulose synthase. Proc. Natl Acad. Sci. USA 109, 4098–4103 (2012)

    ADS  CAS  Article  Google Scholar 

  31. 31

    Montanier, C. et al. Evidence that family 35 carbohydrate binding modules display conserved specificity but divergent function. Proc. Natl Acad. Sci. USA 106, 3065–3070 (2009)

    ADS  CAS  Article  Google Scholar 

  32. 32

    Sancho, J. Flavodoxins: sequence, folding, binding, function and beyond. Cell. Mol. Life Sci. 63, 855–864 (2006)

    CAS  Article  Google Scholar 

  33. 33

    Delmer, D. P. Cellulose biosynthesis: Exciting times for a difficult field of study. Annu. Rev. Plant Physiol. Plant Mol. Biol. 50, 245–276 (1999)

    CAS  Article  Google Scholar 

  34. 34

    Carpita, N. C. Update on mechanisms of plant cell wall biosynthesis: How plants make cellulose and other (1→4)-β-d-glycans. Plant Physiol. 155, 171–184 (2011)

    CAS  Article  Google Scholar 

  35. 35

    Dowd, M. K., French, A. D. & Reilly, P. J. Conformational analysis of the anomeric forms of sophorose, laminarabiose, and cellobiose using MM3. Carbohydr. Res. 233, 15–34 (1992)

    CAS  Article  Google Scholar 

  36. 36

    Momany, F. A. & Schnupf, U. DFTMD studies of β-cellobiose: conformational preference using implicit solvent. Carbohydr. Res. 346, 619–630 (2011)

    CAS  Article  Google Scholar 

  37. 37

    Brown, M. Cellulose structure and biosynthesis: What is in store for the 21st century? J. Pol. Sci. 42, 487–495 (2004)

    CAS  Article  Google Scholar 

  38. 38

    Rapoport, T. A. Protein transport across the endoplasmic reticulum membrane. FEBS J. 275, 4471–4478 (2008)

    CAS  Article  Google Scholar 

  39. 39

    Burton, B. & Dubnau, D. Membrane-associated DNA transport machines. Cold Spring Harb. Perspect. Biol. 2, 1–20 (2010)

    Article  Google Scholar 

  40. 40

    Whitfield, C. Biosynthesis and assembly of capsular polysaccharides in Escherichia coli. Annu. Rev. Biochem. 75, 39–68 (2006)

    CAS  Article  Google Scholar 

  41. 41

    Raetz, C. R. H. & Whitfield, C. Lipopolysaccharide endotoxins. Annu. Rev. Biochem. 71, 635–700 (2002)

    CAS  Article  Google Scholar 

  42. 42

    Emsley, P. & Cowtan, K. Coot: model-building tools for molecular graphics. Acta Crystallogr. D 60, 2126–2132 (2004)

    Article  Google Scholar 

  43. 43

    Studier, F. W. Protein production by auto-induction in high density shaking cultures. Protein Expr. Purif. 41, 207–234 (2005)

    CAS  Article  Google Scholar 

  44. 44

    Leslie, A. G. W. The integration of macromolecular diffraction data. Acta Crystallogr. D 62, 48–57 (2006)

    Article  Google Scholar 

  45. 45

    CCP4. The CCP4 suite: programs for protein crystallography. Acta Crystallogr. D 50, 760–763 (1994)

  46. 46

    Sheldrick, G. M. A short history of SHELX. Acta Crystallogr. A 64, 112–122 (2008)

    ADS  CAS  Article  Google Scholar 

  47. 47

    Cowtan, K. Recent developments in classical density modification. Acta Crystallogr. D 66, 470–478 (2010)

    CAS  Article  Google Scholar 

  48. 48

    Painter, J. & Merritt, E. A. Optimal description of a protein structure in terms of multiple groups undergoing TLS motion. Acta Crystallogr. D 62, 439–450 (2006)

    Article  Google Scholar 

  49. 49

    PyMol. The PYMOL Molecular Graphics System (DeLano Scientific). (2000)

  50. 50

    Ashkenazy, H., Erez, E., Martz, E., Pupko, T. & Ben-Tal, N. ConSurf 2010: calculating evolutionary conservation in sequence and structure of proteins and nucleic acids. Nucleic Acids Res. 38, W529–W533 (2010)

    CAS  Article  Google Scholar 

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We are grateful to G. Murshudov for advice on Refmac refinement and U. and Z. Derewenda for discussions. We thank L. Tamm, M. Wiener, A. Walling and T. Rapoport for critical comments on the manuscript. X-ray diffraction data were collected at GM/CA- and Southeast Regional-Collaborative Access Team beamlines at the Advanced Photon Source (APS), Argonne National Laboratory. Use of the APS was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, contract no. DE-AC02-06CH11357 and W-31-109-Eng-38. GM/CA at APS has been funded in whole or in part with funds from the National Cancer Institute (Y1-CO-1020) and the National Institute of General Medical Sciences (Y1-GM-1104). The University of Georgia CCRC is supported by the Department of Energy funded Center for Plant and Microbial Complex Carbohydrates (DE-FG02-09ER-20097). J.L.W.M. is partially supported by a Peach Fellowship, University of Virginia. J.Z. is support by NIH grant 1R01GM101001 and start-up funds from the University of Virginia School of Medicine.

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J.Z. designed the experiments. J.L.W.M. and J.Z. expressed, purified and crystallized the BcsA–BcsB complex. J.L.W.M. and J.Z. analysed the crystallographic data and built the model. J.S. performed in vitro cellulose synthesis assays. J.L.W.M. and J.Z. wrote the manuscript.

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Correspondence to Jochen Zimmer.

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Morgan, J., Strumillo, J. & Zimmer, J. Crystallographic snapshot of cellulose synthesis and membrane translocation. Nature 493, 181–186 (2013).

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