scytonemin and aminopenicillanic-acid

Cyanobacterium Nostoc commune can tolerate the simultaneous stresses of desiccation, UV irradiation, and oxidation. Acidic WspA, of approximately 33.6 kDa, is secreted to the three-dimensional extracellular matrix and accounts for greater than 70% of the total soluble protein. The wspA gene of N. commune strain DRH1 was cloned and found in a single genomic copy, in a monocistronic operon. Transcription of wspA and sodF (superoxide dismutase), and synthesis and secretion of WspA, were induced upon desiccation or UV-A/B irradiation of cells. Recombinant WspA binds the UV-A/B absorbing pigment scytonemin through non-covalent interactions. WspA peptide polymorphism, and heterogeneity of multiple wspA sequences within cells of a single colony, account for distinct WspA isoforms. WspA has no similarity to entries in the sequence databases and wspA, a possible xenolog, is restricted to a subset of strains in the "form species" N. commune characterized through group I intron phylogeny. We hypothesize that WspA plays a central role in the global stress response of N. commune through modulation of the structure and function of the three-dimensional extracellular matrix, particularly the transport, distribution, and/or macromolecular architecture of mycosporine and scytonemin UV-A/B absorbing pigment complexes.

Topics: Amino Acid Sequence; Base Sequence; Chromatography, Liquid; Extracellular Matrix; Heat-Shock Proteins; Indoles; Isoelectric Focusing; Mass Spectrometry; Models, Chemical; Models, Genetic; Molecular Sequence Data; Nostoc commune; Open Reading Frames; Oxygen; Penicillanic Acid; Peptides; Phenols; Phylogeny; Polymorphism, Genetic; Polysaccharides; Promoter Regions, Genetic; Protein Binding; Protein Structure, Tertiary; Recombinant Proteins; Superoxide Dismutase; Transcription, Genetic; Ultraviolet Rays