Response of Porphyromonas gingivalis to heme limitation in continuous culture.
Porphyromonas gingivalis is an anaerobic, asaccharolytic, gram-negative bacterium that has essential requirements for both iron and protoporphyrin IX, which it preferentially obtains as heme. A combination of large-scale quantitative proteomic analysis using stable isotope labeling strategies and mass spectrometry, together with transcriptomic analysis using custom-made DNA microarrays, was used to identify changes in P. gingivalis W50 protein and transcript abundances on changing from heme-excess to heme-limited continuous culture. This approach identified 160 genes and 70 proteins that were differentially regulated by heme availability, with broad agreement between the transcriptomic and proteomic data. A change in abundance of the enzymes of the aspartate and glutamate catabolic pathways was observed with heme limitation, which was reflected in organic acid end product levels of the culture fluid. These results demonstrate a shift from an energy-efficient anaerobic respiration to a less efficient process upon heme limitation. Heme limitation also resulted in an increase in abundance of a protein, PG1374, which we have demonstrated, by insertional inactivation, to have a role in epithelial cell invasion. The greater abundance of a number of transcripts/proteins linked to invasion of host cells, the oxidative stress response, iron/heme transport, and virulence of the bacterium indicates that there is a broad response of P. gingivalis to heme availability.
Dashper
Stuart G
SG
Cooperative Research Centre for Oral Health Science, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia.
Ang
Ching-Seng
CS
Veith
Paul D
PD
Mitchell
Helen L
HL
Lo
Alvin W H
AW
Seers
Christine A
CA
Walsh
Katrina A
KA
Slakeski
Nada
N
Chen
Dina
D
Lissel
J Patricia
JP
Butler
Catherine A
CA
O'Brien-Simpson
Neil M
NM
Barr
Ian G
IG
Reynolds
Eric C
EC
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002853:Chromatography, Liquid; D003470:Culture Media / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006418:Heme / Q000494:pharmacology*; D013058:Mass Spectrometry; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D016966:Porphyromonas gingivalis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D040901:Proteomics / Q000379:methods; D014158:Transcription, Genetic / Q000187:drug effects
D001426:Bacterial Proteins; D003470:Culture Media; D006418:Heme