An engineered multidomain fungicidal peptide against plant fungal pathogens / 生理学报

Fungal pathogens represent major problems for human health and agriculture. As eukaryotic organisms, fungi share some important features with mammalian cells. Therefore, current anti-fungal antibiotics often can not distinguish between fungi and mammalian cells, resulting in serious side effects in mammalian cells. Accordingly, there is strong impetus to develop antifungal alternatives that are both safe and effective. The E1 family of colicin are channel-forming bacteriocins produced by Escherichia coli, which are bactericidal only to E. coli and related species. To target the channel-forming domain of colicin to fungal cell membrane, we engineered a sexual mating pheromone of Candida albicans, α-factor pheromone to colicin Ia. A peptide was constructed consisting of an α mating pheromone of C. albicans fused to the channel-forming domain of colicin Ia to create a new fusion protein, pheromonicin-CA (PMC-CA). Indirect immunolabeling showed that the PMC-CA bound to fungal cells and inhibited growth in the laboratory and field. In the field, the protective activity of pheromonicin against rice blast disease was significantly greater, on a molar basis, than that of triazoles, tricyclazole or isoprothiolane. These results suggest that fusion peptides may be of value as fungicidal agents under agricultural conditions.

In-vitro catabolism of L-histidine by adult schistosoma mansoni

Coupled pairs of Schistosoma mansoni retrieved from mice 6 weeks after infection, were incubated in Hank's medium containing uniformly labelled [14C] L-histidine. After 3 hours of incubation analysis of the medium by column and paper chrormatography demonstrated the presence of [14C] labeled: histamine, urocanic acid, glutamic acid, imidazolepyruvic acid and imidazoleacetic acid. Non-radiolabelled glycine and alanine were also found in the medium. We conclude that histidine is rapidly taken up from medium by S. mansoni and is metabolized via decarboxylation, deamination and transamination pathways and that these products are released by the worms into their environment