K-111. Genome Based Metabolic Analysis and Growth Medium of MRSA Staphylococcus aureus

V. Kapatral1, H. Burd1, Z. Oltvai2;
1Integrated Genomics, Chicago, IL, 2Univ. of Pittsburg, Pittsburgh, PA.

We analyzed multiple S.aureus genomes for metabolic and flux balance analysis. As a test model of our approach we chose S. aureus N315 strain using whole genome annotation and pathways using ERGO genome discovery tools. 2,593 ORFs were identified on chromosome and 31 ORFs on the plasmid, of which 2,505 ORFs were assigned with a functional role. A total of 906 ORFs were identified to have an enzymatic activity (i e. have EC numbers) and 474 ORFs have unique complete EC numbers. For all the ORFs with EC numbers, the enzyme reactions were identified from ERGO and KEGG pathway databases. A set of 1,174 reactions catalyzed by 474 unique enzymes were used in the flux balance analysis. Based on the metabolic reconstruction we identified histidine, L-homo cysteine, L-asparagine,L-serine, phosphotidyl-choline, phosphotidyl-serine, phosphotidyl-enthanolamine, phosphotidyl 1D-myo inositol are not synthesized by N315 strain. Similarly, fatty acids modifying pathways, aromatic hydrocarbons, phosphonate, tetrahydrobiopterin, molybdenum cofactors, pyridoxine, phylloquinone, PQQ, ubiquinone, tocopherol and plastoquinone are not synthesized as well. Using these analyses, we have designed a minimal medium for growth of MRSA N315 strain. Dedicated transport systems for salt components have been identified, however for amino acids such as arginine, glutamic acid, valine, threonine and phenylalanine, biosynthetic pathways and transport systems were identified. Pathways for co-factors such as biotin, pantothenate have been identified hence these compounds may not be required for the growth of N315 in minimal media.