Novel thermostable glycosidases in the extracellular matrix of the terrestrial cyanobacterium Nostoc commune.
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.
Morsy
Fatthy Mohamed
FM
Division of Life Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa, Japan.
Kuzuha
Satomi
S
Takani
Yayoi
Y
Sakamoto
Toshio
T
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
D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D005696:Galactosidases; D005959:Glucosidases; D006026:Glycoside Hydrolases