4PFW

Crystal structure of mannohexaose bound oligopeptide ABC transporter, periplasmic oligopeptide-binding protein (TM1226) from THERMOTOGA MARITIMA at 2.2 A resolution

Summary for 4PFW

• Entry DOI: 10.2210/pdb4pfw/pdb
• Related: 4PFT 4PFU 4PFY
• Descriptor: ABC transporter substrate-binding protein, beta-D-mannopyranose-(1-4)-beta-D-mannopyranose-(1-4)-beta-D-mannopyranose-(1-4)-beta-D-mannopyranose-(1-4)-alpha-D-mannopyranose-(1-4)-alpha-D-mannopyranose, MAGNESIUM ION, ... (6 entities in total)
• Functional Keywords: oligopeptide abc transporter, periplasmic oligopeptide-binding protein, transport protein
• Biological source: Thermotoga maritima
• Total number of polymer chains: 2
• Total formula weight: 130457.19

Authors

Lu, X.,Ghimire-Rijal, S.,Cuneo, M.J. (deposition date: 2014-04-30, release date: 2014-09-17, Last modification date: 2023-12-27)

Primary citation

Ghimire-Rijal, S.,Lu, X.,Myles, D.A.,Cuneo, M.J.
Duplication of Genes in an ATP-binding Cassette Transport System Increases Dynamic Range While Maintaining Ligand Specificity.
J.Biol.Chem., 289:30090-30100, 2014

PubMed Abstract: Many bacteria exist in a state of feast or famine where high nutrient availability leads to periods of growth followed by nutrient scarcity and growth stagnation. To adapt to the constantly changing nutrient flux, metabolite acquisition systems must be able to function over a broad range. This, however, creates difficulties as nutrient concentrations vary over many orders of magnitude, requiring metabolite acquisition systems to simultaneously balance ligand specificity and the dynamic range in which a response to a metabolite is elicited. Here we present how a gene duplication of a periplasmic binding protein in a mannose ATP-binding cassette transport system potentially resolves this dilemma through gene functionalization. Determination of ligand binding affinities and specificities of the gene duplicates with fluorescence and circular dichroism demonstrates that although the binding specificity is maintained the Kd values for the same ligand differ over three orders of magnitude. These results suggest that this metabolite acquisition system can transport ligand at both low and high environmental concentrations while preventing saturation with related and less preferentially metabolized compounds. The x-ray crystal structures of the β-mannose-bound proteins help clarify the structural basis of gene functionalization and reveal that affinity and specificity are potentially encoded in different regions of the binding site. These studies suggest a possible functional role and adaptive advantage for the presence of two periplasmic-binding proteins in ATP-binding cassette transport systems and a way bacteria can adapt to varying nutrient flux through functionalization of gene duplicates.

PubMed: 25210043
DOI: 10.1074/jbc.M114.590992

Experimental method

X-RAY DIFFRACTION (2.198 Å)