Novel water stress protein from a desiccation-tolerant cyanobacterium. Purification and partial characterization.
A desiccation-tolerant cyanobacterium Nostoc commune accumulates a novel group of acidic proteins when colonies are subjected to repeated cycles of drying and rehydration. The proteins occur in high concentrations; they have isoelectric points between 4.3 and 4.8 and apparent molecular masses between 30 and 39 kDa. The purification of three of these proteins with molecular masses of 33, 37, and 39 kDa is described. The amino-terminal sequence of the 39-kDa protein is Ala-Leu-Tyr-Gly-Tyr-Thr-Ile-Gly-Glu. Peptide mapping of the 39- and the 33-kDa proteins, using different protease, gave similar patterns of digestion fragments. The amino acid compositions of the proteins isolated were similar, and each cross-reacted with a polyclonal antibody raised against the largest (39-kDa) protein. The results indicate that the microheterogeneity observed was generated by in vivo proteolysis of the 39-kDa protein. It is suggested that this protein is a water stress protein with a protective function on a structural level.
Scherer
S
S
Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg 24061.
Potts
M
M
D000595:Amino Acid Sequence; D002241:Carbohydrates / Q000032:analysis; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010449:Peptide Mapping; D010940:Plant Proteins / Q000302:isolation & purification*; D014462:Ultrafiltration
D002241:Carbohydrates; D010940:Plant Proteins