CHARACTERIZATION OF STATIONARY-PHASE PROTEINS IN STREPTOMYCES-COELICOLOR A3(2)

Using two-dimensional (2-D) gel electrophoresis, we have analyzed the continuous changes in protein profiles, from exponential to late stati onary phase, of Streptomyces coelicolor cultures growing in liquid min imal medium. Six proteins were purified from 2-D gels and characterize d by N-terminal sequencing. Three amino acid sequences showed a high p ercentage of identity with other known proteins. Two of them match wit h the iron/zinc-containing superoxide dismutase recently described in S. coelicolor and the third one with a tellurite resistance protein fr om Alcaligenes sp. The activities of the nickel-containing superoxide dismutase and the iron/zinc superoxide dismutase throughout growth wer e determined in native PAGE. Both activities reached their maximal lev els after post-exponential growth. However, while the nickel superoxid e dismutase reached its maximum during the early stationary phase, the iron/zinc superoxide dismutase peaked during late stationary phase. ( C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V.