9TA3
Cryo-EM structure of Heyndrickxia coagulans beta-galactosidase
Summary for 9TA3
| Entry DOI | 10.2210/pdb9ta3/pdb |
| EMDB information | 55743 |
| Descriptor | Beta-galactosidase LacZ, ZINC ION, CHLORIDE ION, ... (4 entities in total) |
| Functional Keywords | beta-galactosidase, heyndrickxia coagulans, transgalactosylation, hydrolase |
| Biological source | Heyndrickxia coagulans |
| Total number of polymer chains | 6 |
| Total formula weight | 462234.34 |
| Authors | Sanita, G.,Maresca, E.,Aulitto, M.,Capaldi, S.,Esposito, E.,Contursi, P. (deposition date: 2025-11-18, release date: 2026-04-29, Last modification date: 2026-05-06) |
| Primary citation | Sanita, G.,Maresca, E.,Capaldi, S.,Casillo, A.,Aulitto, M.,Donadio, F.,Pape, T.,Corsaro, M.M.,Esposito, E.,Contursi, P. CryoEM structural analysis of a thermophilic galactooligosaccharides-producer beta-galactosidase unravels an uncommon oligomeric structure. Int.J.Biol.Macromol., 362:151980-151980, 2026 Cited by PubMed Abstract: Thermostable β-galactosidases represent promising biocatalysts for lactose hydrolysis and production of structurally defined galacto-oligosaccharides (GOS). Here we report the cryo-EM structure of the glycoside hydrolase family 42 (GH42) β-galactosidase from Heyndrickxia coagulans MA-13 (HcGalB), determined at 2.97 Å resolution. HcGalB adopts a canonical tripartite architecture and assembles into a barrel-like homo-hexamer composed of two staggered trimers that interact in an unusual top-to-top configuration. This quaternary arrangement contributes not only to structural stability but also to the modulation of substrate channeling and catalytic properties. Molecular docking revealed a surface groove shaped by conserved aromatic residues that might guide the substrate towards the catalytic pocket. Moreover, the structural data provide a mechanistic rationale for the efficient transgalactosylation activity of HcGalB, which predominantly generates β (1 → 3)-linked GOS, along with β(1 → 6) and β(1 → 4) linkages, as confirmed by 2D Nuclear Magnetic Resonance. Overall, these findings expand the structural landscape of GH42 enzymes and identify architecture-specific determinants that can be leveraged to optimize GH42 catalysts for industrial and functional food applications. PubMed: 41985809DOI: 10.1016/j.ijbiomac.2026.151980 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (2.97 Å) |
Structure validation
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