High-resolution structure of a modular hyperthermostable endo-β-1,4-mannanase from Thermotoga petrophila: The ancillary immunoglobulin-like module is a thermostabilizing domain

• Published in: Biochimica et biophysica acta. Proteins and proteomics Vol. 1868; no. 8; p. 140437
• Main Authors: da Silva, Viviam M., Cabral, Aline D., Sperança, Marcia A., Squina, Fabio M., Muniz, João Renato C., Martin, Lydie, Nicolet, Yvain, Garcia, Wanius
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2020; Elsevier
• Subjects: Biochemistry, Molecular Biology; Hyperthermostability; Immunoglobulin-like domain; Life Sciences; Structural Biology; Thermostabilizing domain; Thermostabilizing domain; Hyperthermostability; Immunoglobulin-like domain
• ISSN: 1570-9639; 1878-1454
• DOI: 10.1016/j.bbapap.2020.140437

The endo-β-1,4-mannanase from the hyperthermostable bacterium Thermotoga petrophila (TpMan) is an enzyme that catalyzes the hydrolysis of mannan and heteromannan polysaccharides. Of the three domains that comprise TpMan, the N-terminal GH5 catalytic domain and the C-terminal carbohydrate-binding domain are connected through a central ancillary domain of unknown structure and function. In this study, we report the partial crystal structure of the TpMan at 1.45 Å resolution, so far, the first modular hyperthermostable endo-β-1,4-mannanase structure determined. The structure exhibits two domains, a (β/α)8-barrel GH5 catalytic domain connected via a linker to the central domain with an immunoglobulin-like β-sandwich fold formed of seven β-strands. Functional analysis showed that whereas the immunoglobulin-like domain does not have the carbohydrate-binding function, it stacks on the GH5 catalytic domain acting as a thermostabilizing domain and allowing operation at hyperthermophilic conditions. The carbohydrate-binding domain is absent in the crystal structure most likely due to its high flexibility around the immunoglobulin-like domain which may act also as a pivot. These results represent new structural and functional information useful on biotechnological applications for biofuel and food industries. •High-resolution structure of the endo-β-1,4-mannanase from T. petrophila (TpMan).•TpMan is flexible while the truncated TpMan behaves like a compact molecule.•Central domain stacks on the catalytic domain forming a large interface area.•Central domain has an immunoglobulin-like β-sandwich fold.•The central ancillary immunoglobulin-like module is a thermostabilizing domain.