Studies on lipidification of streptokinase: a novel strategy to enhance the stability and activity.

Thrombotic disorders and their associated problems are extensively prevalent in developed and developing countries. Streptokinase (SK) is a well-known thrombolytic agent, which is very useful in treating coronary thrombosis and acute myocardial infarction. Several attempts have been made to date to make improvements of this wonderful molecule in terms of reducing or eliminating the problems of eliciting immunogenicity and enhancing the half-life of the molecule. The present research is focused to produce a recombinant SK with enhanced stability and biological activity by the methodology of lipid modification. SK was targeted successfully to the membrane with the help of modified apyrase signal sequence. Higher expression was reported for GJ1158 strain in LBON medium when compared with BL21 (DE3). The obtained recombinant SK was tested for its biological activity by the method of caseinolytic assay. The higher clearance zone was observed in recombinant lipid-modified streptokinase, which denotes the enhanced activity of the protein. The present trial of lipid modification of therapeutics, particularly SK, could help for its superior use as a thrombolytic agent and also paves way for many of the other clinical applications.

Anti-tuberculosis treatment enhances the production of IL-22 through reducing the frequencies of regulatory B cell.

IL-22 has been suggested to play an important role in immune response against Mycobacterium tuberculosis infection. However, the exact role of IL-22 in human tuberculosis (TB) infection remains unclear and the regulatory mechanism of IL-22 response in human TB is unknown. In this study, we observed that successful anti-tuberculosis treatment induced an enhanced and sustained M. tuberculosis antigen-specific IL-22 response, correlated with the decrease of the frequencies of CD19(+)CD5(+)CD1d(+) regulatory B cells. We also found that depletion of CD19(+) B cells significantly enhanced M. tuberculosis antigen-specific IL-22 production by peripheral blood mononuclear cells. More importantly, we observed that purified CD19(+) B cells, and more efficiently, CD19(+)CD5(+)CD1d(+) regulatory B cells, suppressed IL-22 production. In summary, we showed here for the first time that effective anti-tuberculosis treatment restores M. tuberculosis antigen-specific IL-22 response through a novel mechanism by reducing the frequencies of CD19(+)CD5(+)CD1d(+) regulatory B cells in human TB.

Rare codon priority and its position specificity at the 5' of the gene modulates heterologous protein expression in Escherichia coli.

Rare codons and their effects in heterologous protein expression in Escherichia coli were addressed by many investigators. Here, we propose that not all rare codons of a foreign gene have negative effect but selective codon among them and its specific position in the downstream of the start codon modulates the expression. In our study, streptokinase (47 kDa), encoded by skc gene of Streptococcus equisimilis was expressed in E.coli. The analysis of relative codon frequency of skc gene in E.coli reveals the presence of 30% of rare codons in it. Nevertheless, E.coli managed to yield over-expression of this target protein. To explore the codon bias in expression, we have introduced the selective AGG codon at different positions of skc gene such as +2,+3,+5,+8,+9 and +11. The results revealed that at +2 position "AGG" aided over-expression while shifting to +3 and +5 positions it rendered nil expression. In contrary, shifting of AGG codon to later positions like +9 and +11 the inhibitory effect was reversed and resulted in over-expression. The effect of 'AGG' rare codon was further studied in GFP expression. In conclusion, besides the choice of rare codons, their precise positions in the foreign gene dictate the level of protein expression.