title: Novel thermostable glycosidases in the extracellular matrix of the terrestrial cyanobacterium Nostoc commune.
abstract: The cyanobacterium Nostoc commune is adapted to the terrestrial environment and forms a visible colony in which the cells are embedded in extracellular polysaccharides (EPSs), which play a crucial role in the extreme desiccation tolerance of this organism. When natural colonies were immersed in water, degradation of the colonies occurred within 2 days and N. commune cells were released into the water. The activities that hydrolyze glycoside bonds in various N. commune fractions were examined using artificial nitrophenyl-linked sugars as substrates. A beta-D-glucosidase purified from the water-soluble fraction was resistant to 20 min of boiling. The beta-D-glucosidase, with a molecular mass of 20 kDa, was identified as a cyanobacterial fasciclin protein based on its N-terminal amino-acid sequence. The 36-kDa major protein in the water-soluble fraction was purified, and the N-terminal amino-acid sequence of the protein was found to be identical to that of the water-stress protein (WspA) of N. commune. This WspA protein also showed heat-resistant beta-D-galactosidase activity. The fasciclin protein and WspA in the extracellular matrix may play a role in the hydrolysis of the EPSs surrounding the cells, possibly as an aid in the dispersal of cells, thus expanding the colonies of this cyanobacterium.
authors.affiliation: Division of Life Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa, Japan.
authors.forename: Fatthy Mohamed
authors.initials: FM
authors.lastname: Morsy
authors.forename: Satomi
authors.initials: S
authors.lastname: Kuzuha
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Takani
authors.forename: Toshio
authors.initials: T
authors.lastname: Sakamoto
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D004795:Enzyme Stability; D005109:Extracellular Matrix / Q000737:chemistry / Q000201:enzymology*; D005696:Galactosidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D005959:Glucosidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006358:Hot Temperature; D050501:Nostoc commune / Q000201:enzymology*; D011135:Polysaccharides, Bacterial / Q000737:chemistry; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D005696:Galactosidases; D005959:Glucosidases; D006026:Glycoside Hydrolases