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 WillhiteBIOL398-01/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

o Biosynthesis catalyzed by

oMur A-F and MurG enzymes (1-4 steps)

oFilled hexagons

oPeptidoglycan

oGlcNac: N-acetylglucosamine

oMurNac: N-acetyl-muramic acid

oOrange circles

oCarrier lipids- bactoprenol-phosphate

oTransglycosylation and

pyrophosphorylation (steps 5&6)

oPeptide bond between chains

oThose 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

Stage I Biosynthesis pathway

Stage I Biosynthesis pathway

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

Stage I Biosynthesis pathway

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 processF

ormation of carboxylic acids

• Cellular amine biosynthetic processN

aturally occuring biologically active amines

Stage I Biosynthesis pathway

MurA Decrease

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