*3.3. Sequence Analyses and Homology Modelling*

The PL7 lyases were inspected for the presence of additional functional domains via the Interproscan server (version 83.0) [37]. For phylogenetic analysis protein sequences of 11 alginate lyases with solved structures belonging to the PL7 family were selected in the CAZy database [38]. Multiple sequence alignment of PL7 catalytic domains was performed using ClustalX implemented in MEGA-X (version 10.1.8) and manually corrected [39]. A maximum-likelihood phylogeny with 100 non-parametric bootstrap replicates was calculated using the IQ-TREE web server (version 1.6.12) and the WAG+I+G4 substitution model determined using ModelFinder [40,41].

The pairwise sequence identities were calculated by Clustal (version 2.1) using EMBL-EBI Services [42]. The 3D-structures of paralogous PL7 alginate-lyases from SF3, SF5, and SF6 were generated using homology modeling by the Molecular Operating Environment (MOE, version 2020.09) [43]. The crystal structures of the AlyA1 and AlyA5 from *Z. galactanivorans* DsijT, AlyQ from *Persicobacter* sp. CCB-QB2, and FlAlyA from *Flavobacterium* sp. UMI-01 with PDB codes 3ZPY, 4BE3, 5XNR, and 5Y33, respectively, were used as the initial templates. Structure-based sequence alignments were visualized with ESPript 3 [44].
