Project description:Notexin from Notechis scutatus scutatus snake venom was subjected to tyrosine modification with p-nitrobenzenesulphonyl fluoride (NBSF), and four modified derivatives were separated by h.p.l.c. The results of amino acid analysis and sequence determination revealed that only Tyr-7, Tyr-70 and Tyr-77 were modified in notexin. Modification of Tyr-7 resulted in decreases in lethal toxicity and enzymic activity by 70.2% and 22.7% respectively. Conversely, modification of Tyr-77 caused a 1.8-fold increase in enzymic activity, in contrast with the loss of 52.5% of lethality. A drastic decrease in lethal toxicity was observed when both Tyr-7 and Tyr-70 were modified, whereas the enzymic activity decreased by only 35.8%. Likewise, the derivative in which Tyr-7 and Tyr-77 were modified retained 44.4% of enzymic activity, but showed a marked decrease in lethal toxicity. It is obvious that modification of tyrosine residues causes a decrease in lethal toxicity of notexin, which does not directly correlate with the change in enzymic activity. On the other hand, the antigenicity of NBS derivatives remained unchanged. The modified derivatives retained their affinity for Ca2+, indicating that the modified tyrosine residues did not participate in Ca2+ binding. These results indicate that modification of tyrosine residues can differentially influence the enzymic activity and lethal toxicity of notexin, and suggest that notexin might possess two functional sites, one being responsible for the catalytic activity and the other associated with its lethal effect.
Project description:Saccharomonospora azurea Runmao et al. 1987 is a member of the genus Saccharomonospora, which is in the family Pseudonocardiaceae and thus far poorly characterized genomically. Members of the genus Saccharomonospora are of interest because they originate from diverse habitats, such as leaf litter, manure, compost, the surface of peat, and moist and over-heated grain, and may play a role in the primary degradation of plant material by attacking hemicellulose. Next to S. viridis, S. azurea is only the second member in the genus Saccharomonospora for which a completely sequenced type strain genome will be published. Here we describe the features of this organism, together with the complete genome sequence with project status 'Improved high quality draft', and the annotation. The 4,763,832 bp long chromosome with its 4,472 protein-coding and 58 RNA genes was sequenced as part of the DOE funded Community Sequencing Program (CSP) 2010 at the Joint Genome Institute (JGI).