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Transcriptional Signature following Inhibition of Early-Stage Cell Wall Biosynthesis in Staphylococcus aureus. A.J O’Neil, J. A. Lindsay, K. Gould, J. Hinds, and I. Chopra. ( 2009) Antimicrobial Agents and Chemotherapy 01309-08: 1701-1704. Angela Garibaldi & Ryan Willhite
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Transcriptional Signature following Inhibition of Early-Stage Cell Wall Biosynthesis in Staphylococcus aureus A.J O’Neil, J. A. Lindsay, K. Gould, J. Hinds, and I. Chopra (2009)Antimicrobial Agents and Chemotherapy 01309-08: 1701-1704 Angela Garibaldi & Ryan Willhite BIOL398-01/S10: Bioinformatics Laboratory April 27, 2010
Outline • Review of the Experimental Set up • Cell Wall Biosynthesis • Review of the State I Biosynthesis Pathway • Results of GenMAPP, using MAPPfinder tool • Top 10 GO Terms • Relation of significant GO Terms to CWB • Conclusions
Experimental Design • Inhibit the Mur enzymes (A/Z, B, and E) • 3 Biological Replicates • 2 Technical Replicates • 18 hybridizations (6 per condition) • Dye swap design – label orientations are reversed
Overview of Cell Wall Biosynthesis Biosynthesis catalyzed by Mur A-F and MurG enzymes (1-4 steps) Filled hexagons Peptidoglycan GlcNac: N-acetylglucosamine MurNac: N-acetyl-muramic acid Orange circles Carrier lipids- bactoprenol-phosphate Transglycosylation and pyrophosphorylation (steps 5&6) Peptide bond between chains Those in pink boxes are antibiotics and their ways of inhibiting cell-wall synthesis http://images.google.com/imgres?imgurl=http://www.nature.com/nrmicro/journal/v1/n1/images/nrmicro727-f2.jpg&imgrefurl=http://www.nature.com/nrmicro/journal/v1/n1/fig_tabnrmicro727_F2.html
MurB Decrease RNA Modification Transferase activity- peptidal link formation RNA processing- capping, polyadenylation and splicing of mRNA
MurB Increase • Antioxidant activity • Breaking chain reaction normally leading to biological damage • Biotin biosynthesis • Plays role in gluconeogenesis • Amide metabolism
MurE Decrease • Translation • RNA Binding • Non-membrane bound organelle
MurE Increase • Amine biosynthetic process Results in formation of organic compound with amino group • Carboxylic acid biosynthetic process Formation of carboxylic acids • Cellular amine biosynthetic process Naturally occuring biologically active amines
MurA Increase • Polysacchairide transmebrane transporter activity • polysaccharide localization • Arsenate reductase activity
Conclusions • Not very conclusive results • Terms mostly involved with biological processes of a cell • Those decreased are essential to cell gene expression and functional protein synthesis, so still unclear on specific relationships