Figure 1.

Bioinformatic analysis of the core-MetE_CBDB from Dehalococcoides mccartyi strain CBDB1. (a) Maximum-Likelihood phylogenetic tree of MetE representatives was generated with MEGA7⁶⁷. Multiple amino acid sequence alignments of full length with deletion of gaps (MUSCLE algorithm) were used to generate the tree. The analysis involved 39 amino acid sequences including the C-terminus of tandem-repeat methionine synthases (tr-MetE) from bacteria (brown colors) and yeast (green) as well as core-MetEs from archaea (blue colors), Chloroflexi (red) and Clostridiales (brown). The gene loci are in brackets. (b) The crystal structure of core-MetE_CBDB was calculated with the I-TASSER server⁶⁵. Overlay of the crystal structure of tr-MetE from Neurospora crassa (PDB No. 4ZTX, grey) with the structural model obtained for core-MetE_CBDB from D. mccartyi strain CBDB1 (green) was obtained with PyMOL⁶⁶. Core-MetE_CBDB matches the C-terminal part of tr-MetE_Ncra (C-score = −0.27) but lacks the N-terminal part and the linker region. (c) Amino acid sequence alignment of selected MetE proteins. The Zn²⁺-binding site HXCX_nC (red) is conserved in annotated tr-MetEs and also in core-MetE homologs. Core-MetE_CBDB: core-MetE from D. mccartyi strain CBDB1, coreMetE_Dehly: core-MetE from Dehalogenimonas lykanthroporepellens, core-MetE_MMKA: core-MetE from Methanococcus maripaludis, tr-MetE_ECDH: tandem-repeat MetE from Escherichia coli DH10B, tr-MetE_Sau: tandem-repeat MetE from Staphylococcus aureus.