Abstract
Synechocystis sp. PCC6803 extracellularly produced a hemolysin homolog (gene product of sll1951) by culturing in BG-11 medium supplemented with 3 μM CuSO4. No hemolytic activity was found in the culture medium. The protein was purified by DEAE-cellulose and Superose 6 chromatography. On the latter, the protein was eluted at the position of 560 kDa. When this value is compared with the molecular weight of the monomer, deduced from the DNA sequence, 178 kDa, the protein is likely to form a trimer. The mobility of the protein upon SDS-PAGE largely and reversibly changed by heat: 84-98 kDa when not heated and 224 kDa when heated. This mobility change suggests that the hemolysin homolog underwent a reversible structural change by heat, and is likely to be due to the Ca-binding β-roll motifs in the protein molecule. The Ca content in the protein is now being measured.
