(582ck) Global Alterations in the Secretome of B. Subtilis and S. Cerevisiae

Thio-phosphate is a useful tool for manipulating nucleic acids in vivo as it results in nuclease resistant phosphorothioate linkages and as such can also be used to modulate protein synthesis.  Two dimensional SDS polyacrylamide gel electrophoresis was successfully used to reveal changes in the pattern of protein expression in B. subtilis and S. cerevisiae. Both organisms secrete proteins and global alterations were readily detected in the secretome of these organisms using thio-phosphate. In both organisms, a shift in the distribution of proteins occurred favoring less abundant and/or heterologous proteins at the expense of naturally more abundant proteins. This shift appeared to result from the incorporation of thio-phosphate into the mRNA backbone, preferentially stabilizing less stable mRNAs at the expense of more stable mRNAs. The results revealed a clear correlation between the % total mass of a protein and the fold change in B. subtilis. Furthermore, in S. cerevisiae total protein secretion was enhanced several fold. Thio-phosphate is a potentially useful tool for manipulating protein synthesis and related outputs in  micro-organisms. It also helpful for the detection of less prevalent proteins in the secretome. In B subtilis 853 protein spots were detected compared with 200 proteins previously detected in 2D gels.