4TQU

Crystal structure of a bacterial ABC transporter involved in the import of the acidic polysaccharide alginate

Summary for 4TQU

• Entry DOI: 10.2210/pdb4tqu/pdb
• Related: 4TQV
• Descriptor: AlgM1, AlgM2, AlgS, ... (6 entities in total)
• Functional Keywords: abc, sphingomonas, alginate, transporter, transport protein
• Biological source: Sphingomonas sp.; More
• Total number of polymer chains: 5
• Total formula weight: 208365.50

Authors

Maruyama, Y.,Itoh, T.,Kaneko, A.,Nishitani, Y.,Mikami, B.,Hashimoto, W.,Murata, K. (deposition date: 2014-06-12, release date: 2015-07-22, Last modification date: 2024-03-20)

Primary citation

Maruyama, Y.,Itoh, T.,Kaneko, A.,Nishitani, Y.,Mikami, B.,Hashimoto, W.,Murata, K.
Structure of a Bacterial ABC Transporter Involved in the Import of an Acidic Polysaccharide Alginate
Structure, 23:1643-1654, 2015

PubMed Abstract: The acidic polysaccharide alginate represents a promising marine biomass for the microbial production of biofuels, although the molecular and structural characteristics of alginate transporters remain to be clarified. In Sphingomonas sp. A1, the ATP-binding cassette transporter AlgM1M2SS is responsible for the import of alginate across the cytoplasmic membrane. Here, we present the substrate-transport characteristics and quaternary structure of AlgM1M2SS. The addition of poly- or oligoalginate enhanced the ATPase activity of reconstituted AlgM1M2SS coupled with one of the periplasmic solute-binding proteins, AlgQ1 or AlgQ2. External fluorescence-labeled oligoalginates were specifically imported into AlgM1M2SS-containing proteoliposomes in the presence of AlgQ2, ATP, and Mg(2+). The crystal structure of AlgQ2-bound AlgM1M2SS adopts an inward-facing conformation. The interaction between AlgQ2 and AlgM1M2SS induces the formation of an alginate-binding tunnel-like structure accessible to the solvent. The translocation route inside the transmembrane domains contains charged residues suitable for the import of acidic saccharides.

PubMed: 26235029
DOI: 10.1016/j.str.2015.06.021

Experimental method

X-RAY DIFFRACTION (3.204 Å)