4TQV image
Entry Detail
PDB ID:
4TQV
Title:
Crystal structure of a bacterial ABC transporter involved in the import of the acidic polysaccharide alginate
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2014-06-12
Release Date:
2015-07-22
Method Details:
Experimental Method:
Resolution:
4.50 Å
R-Value Free:
0.32
R-Value Work:
0.27
R-Value Observed:
0.28
Space Group:
P 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:AlgM1
Chain IDs:A, E, I, M
Chain Length:301
Number of Molecules:4
Biological Source:Sphingomonas sp.
Polymer Type:polypeptide(L)
Description:AlgM2
Chain IDs:B, F, J, N
Chain Length:305
Number of Molecules:4
Biological Source:Sphingomonas sp.
Polymer Type:polypeptide(L)
Description:AlgS
Mutations:E160Q
Chain IDs:C, D, G, H, K, L, O, P
Chain Length:363
Number of Molecules:8
Biological Source:Sphingomonas sp.
Ligand Molecules
Primary Citation
Structure of a Bacterial ABC Transporter Involved in the Import of an Acidic Polysaccharide Alginate
Structure 23 1643 1654 (2015)
PMID: 26235029 DOI: 10.1016/j.str.2015.06.021

Abstact

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.

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Primary Citation of related structures