 The authors describe the co-crystal structure of the highly efficient polyethylene terephthalate degrading hydrolase pHL7 with its product terephthalic acid and elucidate the role of residues in subsites 1 and 2 for its thermal stability and of residue L210 for its high activity. This article was authored by P. Konstantin Richter, Paula Blasquez-Sanchez, Ziyua Zhao, and others.