Project description:Plants and algae have developed various light harvesting mechanisms for optimal delivery of excitation energy to the photosystems. The cryptophyte algae have evolved a novel soluble light-harvesting antenna utilizing phycobilin pigments to complement the membrane-intrinsic Chl a/c-binding LHC antenna. This new antenna consists of the plastid-encoded beta-subunit, a relict of the ancestral phycobilisome, and a novel nuclear-encoded -subunit unique to cryptophytes. Together, these proteins form the active tetramer, which consists of one alpha 1 and one alpha 2 and two beta susbunits. In all cryptophyte algae investigated so far, the alpha-subunits have duplicated and diversified into a large gene family. Although there is transcriptional evidence for expression of all these genes, the x-ray structures determined to date suggest that only two of the -subunit genes might be significantly expressed at protein level. Using proteomics, we show that phycoerythrin 545 (PE545) of Guillardia theta, the only cryptophyte with a sequenced genome, all 20 alpha-subunits are expressed when the algae grow under white light. Their relative expression levels depend on the intensity of the growth light, but there is no evidence for a specific light-dependent regulation of individual members of the alpha-subunit family under the growth conditions applied. Subunit GtcpeA10 seems to be a special member of the alpha-subunit family, because it consists of two similar N- and C-terminal domains, which likely are the result of a partial gene duplication.
Project description:To investigate the effect of bacterially secreted Theta toxin on lung cancer cells, we established co-culture of live S. typhimurium and spheroids of H460 and H1819 cell lines. Once the bacteria colonized inside the spheroids, we induced the expression of Theta toxin by the bacteria. We extracted RNA after 1 week of treatment.
