ABSTRACT
Symbiotic protists in the gut of termites are prominent natural resources for enzymes involved in lignocellulose degradation. Here we report expression, purification, and biochemical characterization of a glycoside hydrolase family 26 mannanase RsMan26H from the symbiotic protist of the lower termite, Reticulitermes speratus. Biochemical analysis of RsMan26H demonstrates that this enzyme is an endo-processive mannobiohydrolase producing mannobiose from oligo- and polysaccharides, followed by a minor accumulation of oligosaccharides larger than mannobiose. To our knowledge, this is the first report describing the unique mannobiohydrolase enzyme from the eukaryotic origin.
Subject(s)
Mannans/chemistry , Oligosaccharides/chemistry , Parabasalidea/chemistry , Polysaccharides/chemistry , Protozoan Proteins/chemistry , beta-Mannosidase/chemistry , Animals , Gene Expression , Isoptera/physiology , Kinetics , Mannans/metabolism , Oligosaccharides/metabolism , Parabasalidea/enzymology , Pichia/genetics , Pichia/metabolism , Polysaccharides/metabolism , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Symbiosis , beta-Mannosidase/genetics , beta-Mannosidase/metabolismABSTRACT
Phylogenetic trees based on parabasalid sequences of the small subunit rRNA placed Histomonas meleagridis in close proximity to Dientamoeba fragilis, Tritrichomonas foetus, and Monocercomonas sp. In this study, we sequenced partial genes of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), enolase, and alpha-tubulin from 2 strains of H. meleagridis. We found 5 different GAPDH sequences, 6 different enolase sequences, and 3 alpha-tubulin sequences. Phylogenetic trees based on the obtained sequences showed a close relationship of H. meleagridis with T. foetus and, to some extent, Monocercomonas sp. In conclusion, our findings further corroborate the ssu rRNA-based tree. Consequently, our study also supports the hypothesis that H. meleagridis secondarily lost cytoskeletal structures.