HRDE-1 slicer catalytic tetrad check

Script: catalytic_tetrad.py (local BLOSUM62 pairwise alignment of HRDE-1/Q09249
against human AGO2/Q9UKV8, fetched live from UniProt).

AGO2 position AGO2 residue HRDE-1 position HRDE-1 residue conserved
597 D 749 E False
637 E 797 Y False
669 D 829 V False
807 H 966 E False

Alignment score: 385.0.

Interpretation: none of the four AGO2 slicer (DEDH) catalytic positions is
conserved in HRDE-1 in this pairwise alignment. This is consistent with the
published statement that WAGO-clade Argonautes lack key catalytic residues
(Shirayama et al. 2012, PMID:22738726). Caveat: a single pairwise alignment
can shift by a few residues in poorly conserved regions; a family MSA would be
more definitive, but no residue matching the tetrad pattern was observed.