Molecular mechanism underlying high-affinity terephthalate binding and conformational change of TBP from Ideonella sakaiensis.

Ideonella sakaiensis is the bacterium that can survive by degrading polyethylene terephthalate (PET) plastic, and terephthalic acid (TPA) binding protein (Is TBP) is an essential periplasmic protein for uptake of TPA into the cytosol for complete degradation of PET. Here, we demonstrated that Is TBP has remarkably high specificity for TPA among 33 monophenolic compounds and two 1,6-dicarboxylic acids tested. Structural comparisons with 6-carboxylic acid binding protein (Rp AdpC) and TBP from Comamonas sp. E6 (Cs TphC) revealed the key structural features that contribute to high TPA specificity and affinity of Is TBP. We also elucidated the molecular mechanism underlying the conformational change upon TPA binding. In addition, we developed the Is TBP variant with enhanced TPA sensitivity, which can be expanded for the use of TBP as a biosensor for PET degradation. • Investigation of periplasmic terephthalate transport protein in I.sakaiensis (Is TBP). • Characterization of Is TBP with a high affinity for TPA • Determination of conformational change mechanism of TBP • Development of higher TPA sensitivity of TPA binding protein [ABSTRACT FROM AUTHOR]