Download MendeleyCrystal structure of a homotrimeric verrucomicrobial exo - beta -1,4-mannosidase active in the hindgut of the wood-feeding termite Reticulitermes flavipes .
Kalyani, D.C., Reichenbach, T., Keskitalo, M.M., Conrad, J., Aspeborg, H., Divne, C.(2021) J Struct Biol X 5: 100048-100048
- PubMed: 34195602
- DOI: https://doi.org/10.1016/j.yjsbx.2021.100048
- Primary Citation of Related Structures:
7BOB - PubMed Abstract:
The termite Reticulitermes flavipes causes extensive damage due to the high efficiency and broad specificity of the ligno- and hemicellulolytic enzyme systems produced by its symbionts. Thus, the R. flavipes gut microbiome is expected to constitute an excellent source of enzymes that can be used for the degradation and valorization of plant biomass. The symbiont Opitutaceae bacterium strain TAV5 belongs to the phylum Verrucomicrobia and thrives in the hindgut of R. flavipes . The sequence of the gene with the locus tag opit5_10225 in the Opitutaceae bacterium strain TAV5 genome has been classified as a member of glycoside hydrolase family 5 (GH5), and provisionally annotated as an endo - β -mannanase. We characterized biochemically and structurally the opit5_10225 gene product, and show that the enzyme, Op5 Man5, is an exo - β -1,4-mannosidase [EC 3.2.1.25] that is highly specific for β -1,4-mannosidic bonds in mannooligosaccharides and ivory nut mannan. The structure of Op5 Man5 was phased using electron cryo-microscopy and further determined and refined at 2.2 Å resolution using X-ray crystallography. Op5 Man5 features a 200-kDa large homotrimer composed of three modular monomers. Despite insignificant sequence similarity, the structure of the monomer, and homotrimeric assembly are similar to that of the GH42-family β -galactosidases and the GH164-family exo - β -1,4-mannosidase Bs 164 from Bacteroides salyersiae . To the best of our knowledge Op5 Man5 is the first structure of a glycoside hydrolase from a bacterial symbiont isolated from the R. flavipes digestive tract, as well as the first example of a GH5 glycoside hydrolase with a GH42 β -galactosidase-type homotrimeric structure.
Organizational Affiliation:
School of Engineering Sciences in Chemistry, Biotechnology, and Health (CBH), KTH Royal Institute of Technology, Roslagstullsbacken 21, SE-11421 Stockholm, Sweden.
