Frontiers in Microbiology (Jan 2022)

The Bacteroidetes Aequorivita sp. and Kaistella jeonii Produce Promiscuous Esterases With PET-Hydrolyzing Activity

  • Hongli Zhang,
  • Pablo Perez-Garcia,
  • Pablo Perez-Garcia,
  • Robert F. Dierkes,
  • Violetta Applegate,
  • Julia Schumacher,
  • Cynthia Maria Chibani,
  • Stefanie Sternagel,
  • Lena Preuss,
  • Sebastian Weigert,
  • Christel Schmeisser,
  • Dominik Danso,
  • Juergen Pleiss,
  • Alexandre Almeida,
  • Alexandre Almeida,
  • Birte Höcker,
  • Steven J. Hallam,
  • Steven J. Hallam,
  • Steven J. Hallam,
  • Steven J. Hallam,
  • Steven J. Hallam,
  • Ruth A. Schmitz,
  • Sander H. J. Smits,
  • Sander H. J. Smits,
  • Jennifer Chow,
  • Wolfgang R. Streit

DOI
https://doi.org/10.3389/fmicb.2021.803896
Journal volume & issue
Vol. 12

Abstract

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Certain members of the Actinobacteria and Proteobacteria are known to degrade polyethylene terephthalate (PET). Here, we describe the first functional PET-active enzymes from the Bacteroidetes phylum. Using a PETase-specific Hidden-Markov-Model- (HMM-) based search algorithm, we identified several PETase candidates from Flavobacteriaceae and Porphyromonadaceae. Among them, two promiscuous and cold-active esterases derived from Aequorivita sp. (PET27) and Kaistella jeonii (PET30) showed depolymerizing activity on polycaprolactone (PCL), amorphous PET foil and on the polyester polyurethane Impranil® DLN. PET27 is a 37.8 kDa enzyme that released an average of 174.4 nmol terephthalic acid (TPA) after 120 h at 30°C from a 7 mg PET foil platelet in a 200 μl reaction volume, 38-times more than PET30 (37.4 kDa) released under the same conditions. The crystal structure of PET30 without its C-terminal Por-domain (PET30ΔPorC) was solved at 2.1 Å and displays high structural similarity to the IsPETase. PET30 shows a Phe-Met-Tyr substrate binding motif, which seems to be a unique feature, as IsPETase, LCC and PET2 all contain Tyr-Met-Trp binding residues, while PET27 possesses a Phe-Met-Trp motif that is identical to Cut190. Microscopic analyses showed that K. jeonii cells are indeed able to bind on and colonize PET surfaces after a few days of incubation. Homologs of PET27 and PET30 were detected in metagenomes, predominantly aquatic habitats, encompassing a wide range of different global climate zones and suggesting a hitherto unknown influence of this bacterial phylum on man-made polymer degradation.

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