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170 a.a.
Key reference
DOI no: 10.1016/j.jmb.2005.02.024 J Mol Biol 348:1 (2005) PubMed id: 15808849
Crystal structure of a type-II cohesin module from the Bacteroides cellulosolvens cellulosome reveals novel and distinctive secondary structural elements. I.Noach, F.Frolow, H.Jakoby, S.Rosenheck, L.W.Shimon, R.Lamed, E.A.Bayer. ABSTRACT
The incorporation of enzymes into the multi-enzyme cellulosome complex and its anchoring to the bacterial cell surface are dictated by a set of binding interactions between two complementary protein modules: the cohesin and the dockerin. In this work, the X-ray crystal structure of a type-II cohesin from scaffoldin A of Bacteroides cellulosolvens has been determined to a resolution of 1.6 angstroms using molecular replacement. The type-II B. cellulosolvens cohesin (Bc-cohesin-II) is the first detailed description of a crystal structure for a type-II cohesin, and its features were compared with the known type-I cohesins from Clostridium thermocellum and Clostridium cellulolyticum (Ct-cohesin-I and Cc-cohesin-I, respectively). The overall jelly-roll topology of the type-II Bc-cohesin is very similar to that observed for the type-I cohesins with three additional secondary structures: an alpha-helix and two "beta-flaps" that disrupt the normal course of a beta-strand. In addition, beta-strand 5 is elevated by approximately 4 angstroms on the surface of the molecule, relative to the type-I Ct and Cc-cohesins. Like its type-I analogue, the hydrophobic/aromatic core of Bc-cohesin-II comprises an upper and lower core, but an additional aromatic patch and conserved tryptophan at the crown of the molecule serves to stabilize the alpha-helix of the type-II cohesin. Comparison of Bc-cohesin-II with the known type-I cohesin-dockerin heterodimer suggests that each of the additional secondary structural elements assumes a flanking position relative to the putative dockerin-binding surface. The raised ridge formed by beta-strand 5 confers additional distinctive topographic features to the proposed binding interface that collectively distinguish between the type-II and type-I cohesins.
Selected figure(s)
Figure 6.
Figure 6. Stereo view showing superimposed C^a traces of Bc-cohesin-II (1TYJ, blue), Ct-cohesin-I (1ANU, red) and Cc-cohesin-I (1G1K, green). Superposition was performed using LSQMAN.46Figure 8.
Figure 8. Surface representation of the Bc-cohesin-II molecule versus Ct-cohesin-I in frontal (bottom) and bird's-eye (top) views. (a) Bc-cohesin-II. Orange areas designate the protruding portions of the b-flaps and the magenta color indicates the a-helix on the top of the molecule. Strand b5 (colored yellow) forms a raised ridge relative to the homologous strand in the type-I cohesins. (b) The contact and recognition residues on the type-I Ct-cohesin-I surface are presented in the equivalent orientation. The molecule shown is the cohesin derived from the cohesin-dockerin heterodimer (1OHZ) without the dockerin. Amino acid residues involved in direct hydrogen bonding to the dockerin are colored green, hydrophobic residues in the cohesin-dockerin contact surface are colored gray, and amino acid residues which interact with the dockerin molecule via bridging water molecules are colored cyan.The above figures are reprinted by permission from Elsevier: J Mol Biol (2005, 348, 1-0) copyright 2005. Figures were selected by an automated process.
Literature references that cite this PDB file's key reference
PubMed id Reference
18219699 R.Haimovitz, Y.Barak, E.Morag, M.Voronov-Goldman, Y.Shoham, R.Lamed, and E.A.Bayer (2008).
Cohesin-dockerin microarray: Diverse specificities between two complementary families of interacting protein modules.Proteomics, 8, 968-979.
17360613 A.L.Carvalho, F.M.Dias, T.Nagy, J.A.Prates, M.R.Proctor, N.Smith, E.A.Bayer, G.J.Davies, L.M.Ferreira, M.J.Romão, C.M.Fontes, and H.J.Gilbert (2007).
Evidence for a dual binding mode of dockerin modules to cohesins.Proc Natl Acad Sci U S A, 104, 3089-3094.
PDB code: 2ccl
17367380 H.J.Gilbert (2007).
Cellulosomes: microbial nanomachines that display plasticity in quaternary structure.Mol Microbiol, 63, 1568-1576.
16384918 J.J.Adams, G.Pal, Z.Jia, and S.P.Smith (2006).
Mechanism of bacterial cell-surface attachment revealed by the structure of cellulosomal type II cohesin-dockerin complex.Proc Natl Acad Sci U S A, 103, 305-310.
PDB code: 2b59 The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB code is shown on the right.
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