Metabolic engineering based on systems biology for chemicals production

Computational approach towards promoter sequence comparison via TF mapping using a new distance measure

We propose a method for identifying transcription factor binding sites (TFBS) in the given promoter sequence and mapping the transcription factors (TFs). The proposed algorithm searches the +1 transcription start site (TSS) for eukaryotic and prokaryotic sequences individually. The algorithm was tested with sequences from both eukaryotes and prokaryotes for at least 9 experimentally verified and validated functional TFs in promoter sequences. The order and type of TF binding to the promoter of genes encoding central metabolic pathway (CMP) enzyme was tabulated. A new similarity measure was devised for scoring the similarity between a pair of promoter sequences based on the number and order of motifs. Further, these were grouped in clusters considering the scores between them. The distance between each of the clusters in individual pathway was calculated and a phylogenetic tree was developed. This method is further applied to other pathways such as lipid and amino acid biosynthesis to retrieve and compare experimentally verified and conserved TFBS.

Genome shuffling of Propionibacterium shermanii for improving vitamin B12 production and comparative proteome analysis

Genome shuffling is an efficient approach for the rapid improvement of microbial phenotype. Here we improved vitamin B12 production of Propionibacterium shermanii by genome shuffling based on inactivated protoplast fusion. A genome shuffling strain with titer of vitamin B12 of 2.85 mgl(-1), named Propionibacterium shermanii-F2-3, was obtained. The genome shuffled strain produced about 61% improvement of vitamin B12 over the parent strain after 96 h. Comparative analysis of proteome profile was conducted between Propionibacterium shermanii 17 and F2-3. The expression levels of 38 proteins varied significantly in the genome shuffled strain compared with those in the parent strain. Of these proteins, 22 proteins were up-regulated, 16 proteins were down-regulated. Of the up-regulated proteins, 6 proteins (glutaminyl-tRNA synthetase (GlnS), Delta-aminolevulinic acid dehydratase (HemB), methionine synthase (Meth), riboflavin synthase (RibE), phosphofructo kinase (PfkA) and isocitrate dehydrogenase (Icd) is involved in the vitamin B12 biosynthesis pathway. They may be the key enzymes of vitamin B12 biosynthesis.