Cyanobacterial DNA-binding protein related to Escherichia coli HU.

Abstract

A DNA-binding protein was isolated from 2 cyanobacteria (blue-green algae): Anabaena sp. and Aphanocapsa sp. Its MW determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis is .apprx. 10,000; it is rich in lysine and arginine and lacks tyrosine, tryptophan and cysteine. The proteins from both strains show immunological identity with a similar DNA-binding protein from E. coli, when tested by immunodiffusion with an antiserum prepared against the E. coli protein. The Aphanocapsa and E. coli proteins form compact, rapidly sedimenting complexes with cyanophage or bacteriophage DNA. The similarities between the proteins from cyanobacteria and E. coli suggest a degree of evolutionary conservation comparable to that of the histones of eukaryotes.