Proteomics reveals a core molecular response of Pseudomonas putida F1 to acute chromate challenge.
BACKGROUND
Pseudomonas putida is a model organism for bioremediation because of its remarkable metabolic versatility, extensive biodegradative functions, and ubiquity in contaminated soil environments. To further the understanding of molecular pathways responding to the heavy metal chromium(VI) [Cr(VI)], the proteome of aerobically grown, Cr(VI)-stressed P. putida strain F1 was characterized within the context of two disparate nutritional environments: rich (LB) media and minimal (M9L) media containing lactate as the sole carbon source.


RESULTS
Growth studies demonstrated that F1 sensitivity to Cr(VI) was impacted substantially by nutrient conditions, with a carbon-source-dependent hierarchy (lactate > glucose >> acetate) observed in minimal media. Two-dimensional HPLC-MS/MS was employed to identify differential proteome profiles generated in response to 1 mM chromate under LB and M9L growth conditions. The immediate response to Cr(VI) in LB-grown cells was up-regulation of proteins involved in inorganic ion transport, secondary metabolite biosynthesis and catabolism, and amino acid metabolism. By contrast, the chromate-responsive proteome derived under defined minimal growth conditions was characterized predominantly by up-regulated proteins related to cell envelope biogenesis, inorganic ion transport, and motility. TonB-dependent siderophore receptors involved in ferric iron acquisition and amino acid adenylation domains characterized up-regulated systems under LB-Cr(VI) conditions, while DNA repair proteins and systems scavenging sulfur from alternative sources (e.g., aliphatic sulfonates) tended to predominate the up-regulated proteome profile obtained under M9L-Cr(VI) conditions.


CONCLUSIONS
Comparative analysis indicated that the core molecular response to chromate, irrespective of the nutritional conditions tested, comprised seven up-regulated proteins belonging to six different functional categories including transcription, inorganic ion transport/metabolism, and amino acid transport/metabolism. These proteins might potentially serve as indicators of chromate stress in natural microbial communities.
Thompson
Dorothea K
DK
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA. dthomps4@utk.edu
Chourey
Karuna
K
Wickham
Gene S
GS
Thieman
Stephanie B
SB
VerBerkmoes
Nathan C
NC
Zhang
Bing
B
McCarthy
Andrea T
AT
Rudisill
Matt A
MA
Shah
Manesh
M
Hettich
Robert L
RL
D015415:Biomarkers / Q000378:metabolism; D002840:Chromates / Q000378:metabolism / Q000494:pharmacology*; D002853:Chromatography, Liquid; D003470:Culture Media / Q000737:chemistry; D004784:Environmental Monitoring; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D013058:Mass Spectrometry; D019216:Metals, Heavy / Q000633:toxicity; D010084:Oxidation-Reduction; D020543:Proteome / Q000378:metabolism; D040901:Proteomics; D016958:Pseudomonas putida / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects
D015415:Biomarkers; D002840:Chromates; D003470:Culture Media; D019216:Metals, Heavy; D020543:Proteome