title: Structure and function of bacterial super-biosystem responsible for import and depolymerization of macromolecules.
abstract: Generally, when microbes assimilate macromolecules, they incorporate low-molecular-weight products derived from macromolecules through the actions of extracellular degrading enzymes. However, a Gram-negative bacterium, Sphingomonas sp. A1, has a smart biosystem for the import and depolymerization of macromolecules. The bacterial cells directly incorporate a macromolecule, alginate, into the cytoplasm through a "superchannel", as we named it. The superchannel consists of a pit on the cell surface, alginate-binding proteins in the periplasm, and an ATP-binding cassette transporter in the inner membrane. Cytoplasmic polysaccharide lyases depolymerize alginate into the constituent monosaccharides. Other than the proteins characterized so far, novel proteins (e.g., flagellin homologs) have been found to be crucial for the import and depolymerization of alginate through genomics- and proteomics-based identification, thus indicating that the biosystem is precisely constructed and regulated by diverse proteins. In this review, we focus on the structure and function of the bacterial biosystem together with the evolution of related proteins.
authors.affiliation: Laboratory of Basic and Applied Molecular Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 611-0011, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Hashimoto
authors.forename: Keiko
authors.initials: K
authors.lastname: Momma
authors.forename: Yukie
authors.initials: Y
authors.lastname: Maruyama
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yamasaki
authors.forename: Bunzo
authors.initials: B
authors.lastname: Mikami
authors.forename: Kousaku
authors.initials: K
authors.lastname: Murata
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism; D016680:Genome, Bacterial; D046911:Macromolecular Substances / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001704:Biopolymers; D046911:Macromolecular Substances