Differential gene expression analysis for S.pyogenes SP-STK(-) mutant. Streptococcus pyogenes

This analysis revealed ~17.% of all ORFs (292 out of a total 1697 ORFs) differed by at least 1.5 fold (Log2 +0.6) between the mutant and wild-type strains. Of these, ~45% of the ORFs (130 out of 292 ORFs) revealed at least 2-fold (Log2 +1) differences. The complete spectrum of differentially expressed genes in the muatnt strain revealed almost equal number of genes up (143, 49%) or down-regulated (149, 51%). However, at a higher stringency (at least 2-fold), this distribution revealed slightly more leaning towards down-regulated genes (74 out of 130, 57%) indicating the lack of SP-STK results into down regulation of several genes. Amongst the genes belonging to different functional categories, the most notable genes that were affected by the absence of SP-STK were those correspond to Carbohydrate transport and metabolism (57 out of 292, 20% at low stringency and 32 out of 130 ,~25% at high stringency), phage (28, ~10% at low stringency and 24, ~18% at high stringency), and virulence (5-6% irrespective of stringency level). Almost 20-25% of differentially expressed genes revealed at two stringencies were found to be either with unknown or undefined functions. Keywords: knockout mutant Overall design: This analysis is based on a total of three independent prearations of total RNA from the wild-type S. pyogenes M1SF370 and the isogenic knockout mutant lacking SP-STK (SPy1625). First two preparations included dyeswap experiment and hence repeated twice (exp1-4). The third preparation done only one (Exp#5). Thus, the present analysis is based on five separate experiments