Document Detail

Differential activation of Staphylococcus aureus heme detoxification machinery by heme analogues.
MedLine Citation:
PMID:  24443529     Owner:  NLM     Status:  MEDLINE    
The reactive nature of heme enables its use as an enzymatic cofactor while rendering excess heme toxic. The importance of heme detoxification machinery is highlighted by the presence of various types of these homeostatic systems in Gram-positive and Gram-negative microorganisms. A number of pathogens possess orthologs of the HssRS/HrtAB heme detoxification system, underscoring a potential role this system plays in the survival of bacteria in heme-rich environments such as the vertebrate host. In this work, we sought to determine the role of this system in protection against metalloporphyrin heme analogues identified by previous studies as antimicrobial agents. Our findings demonstrate that only toxic metalloporphyrins maximally activate expression of the Staphylococcus aureus heme detoxification system, suggesting that the sensing mechanism of HssRS might require a component of the associated toxicity rather than or in addition to the metalloporphyrin itself. We further establish that only a subset of toxic metalloporphyrins elicit the oxidative damage previously shown to be a significant component of heme toxicity whereas all toxic noniron metalloporphyrins inhibit bacterial respiration. Finally, we demonstrate that, despite the fact that toxic metalloporphyrin treatment induces expression of S. aureus heme detoxification machinery, the HrtAB heme export pump is unable to detoxify most of these molecules. The ineffectiveness of HrtAB against toxic heme analogues provides an explanation for their increased antimicrobial activity relative to heme. Additionally, these studies define the specificity of HssRS/HrtAB, which may provide future insight into the biochemical mechanisms of these systems.
Catherine A Wakeman; Devin L Stauff; Yaofang Zhang; Eric P Skaar
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2014-01-17
Journal Detail:
Title:  Journal of bacteriology     Volume:  196     ISSN:  1098-5530     ISO Abbreviation:  J. Bacteriol.     Publication Date:  2014 Apr 
Date Detail:
Created Date:  2014-03-07     Completed Date:  2014-05-14     Revised Date:  2014-10-07    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1335-42     Citation Subset:  IM    
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MeSH Terms
Bacterial Proteins / genetics,  metabolism*
Biological Transport
Gene Expression Regulation, Bacterial*
Heme / analogs & derivatives,  metabolism*,  toxicity
Staphylococcal Infections / metabolism,  microbiology*
Staphylococcus aureus / genetics,  metabolism*
Grant Support
Reg. No./Substance:
0/Bacterial Proteins; 42VZT0U6YR/Heme

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