Sequence motifs
The PETase-profile HMM was applied to analyse the conservation of amino
acid residues in the 2930 PETase core domains annotated in the LED
(Table S6 ) in comparison to the equivalent positions in the
PETase from Ideonella sakaiensis (Is PETase, Uniprot
identifier A0A0K8P6T7) and LCC (Uniprot identifier G9BY57). The
catalytic triad, the previously suggested PET binding subsite I, which
includes an aromatic clamp for possible substrate interaction, and PET
binding subsite II from 39 were found to be highly
conserved (Table 2 ). The extension of the second α-helix and
the extended loop region, which were described previously as
functionally relevant in Is PETase, were also found in several
PETase homologues in the LED.
Using the position numbers from Is PETase, we suggest a typical
PETase sequence motif written as follows (with X indicating an arbitrary
amino acid): [YF]87, Q119, X3 139-141, S160, M161,
W185, D206, H237, X6 242-247, followed by one of the
previously published amino acid substitutions from 40.
Interestingly, two sequences from an uncultured bacterium (NCBI:
ACC95208.1) and Alkalilimnicola ehrlichii (NCBI: WP_116302080.1)
were found to comprise the PETase sequence motif and W238, which was
mentioned as an amino acid substitution for improved activity and
substrate binding, and four additional sequences (from Caldimonas
manganoxidans , NCBI: WP_019560450.1, from C. taiwanensis ,
NCBI:WP_062195544.1, from Rhizobacter gummiphilus ,
NCBI:WP_085749610.1, and from Aquabacterium sp., NCBI:
MBI3384080.1) were found to comprise the PETase sequence motif and M241,
which was mentioned as an amino acid substitution for improved
thermostability. These six different and novel protein sequences, each
selected by a sequence motif of seventeen amino acid positions in total,
are proposed for upcoming studies on PETase activity.
Polyurethanes (PUR) active enzymes