Premium
Cellulosomes: microbial nanomachines that display plasticity in quaternary structure
Author(s) -
Gilbert Harry J.
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.05640.x
Subject(s) - cellulosome , cohesin , clostridium thermocellum , biology , protein quaternary structure , microbiology and biotechnology , archaea , biochemistry , protein subunit , computational biology , biophysics , bacteria , genetics , dna , cellulase , chromatin , cellulose , gene
Summary The assembly of proteins that display complementary activities into supramolecular intra‐ and extracellular complexes is central to cellular function. One such nanomachine of considerable biological and industrial significance is the plant cell wall degrading apparatus of anaerobic bacteria termed the cellulosome. The Clostridium thermocellum cellulosome assembles through the interaction of a type I dockerin module in the catalytic entities with one of several type I cohesin modules in the non‐catalytic scaffolding protein. Recent structural studies have provided the molecular details of how dockerin–cohesin interactions mediate both cellulosome assembly and the retention of the protein complex on the bacterial cell surface. The type I dockerin, which displays near‐perfect sequence and structural symmetry, interacts with its cohesin partner through a dual binding mode in which either the N‐ or C‐terminal helix dominate heterodimer formation. The biological significance of this dual binding mode is discussed with respect to the plasticity of the orientation of the catalytic subunits within this supramolecular assembly. The flexibility in the quaternary structure of the cellulosome may reflect the challenges presented by the degradation of a heterogenous recalcitrant insoluble substrate by an intricate macromolecular complex, in which the essential synergy between the catalytic subunits is a key feature of cellulosome function.