Protein expression profiles of Haematococcus pluvialis associated with astaxanthin production using 2-D electrophoresis analysis

초록

The green microalga Haematococcus pluvialis is a powerful source of astaxanthin (3,3'-dihydroxy-?z?carotene-4,4…-dione), a ketocarotenoid pigment, with potential effects of antioxidant. Two kinds of cells were prepared: the immature green aplanospores under optimal cell culture conditions and, mature red cysts under astaxanthin inducing stress conditions. The protein expression profiles of these two states were analyzed by 2-D electrophoresis. Both the native- and the denatured SDS-polyacrylamid electrophoresis (PAGE) were performed to compare expressed proteins of H. pluvialis and 2-dimensional electrophoresis was also carried out to identify different protein spots. Native-PAGE showed different patterns between mature cyst cells and immature green cells. By the SDS-PAGE analysis, proteins with molecular weight of 57 kDa, 47 kDa and 43 kDa, were expressed only in mature cells. More detailed protein expression patterns between immature green and mature cyst cells were compared by 2-D electrophoresis analysis. There were much more spots in higher molecular weight and acidic regions in the expressed proteins from mature cells while basic low molecular weight proteins were relatively abundant in immature green aplanospores. Among the different spots, 22 proteins that found in only mature cyst cells were selected and further analyzed by chemically assisted fragmentation (CAF)-MALDI sequencing to identify their functions. Especially, a protein that has pI 5.38 and 32 kDa was identified as light-independent protochlorophyllide reductase iron-sulfur ATP-binding protein. Further study may reveal the relationship between this enzyme and astaxanthin synthesis.