Document Detail


Plasmodium falciparum acyl carrier protein crystal structures in disulfide-linked and reduced states and their prevalence during blood stage growth.
MedLine Citation:
PMID:  19768685     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Acyl Carrier Protein (ACP) has a single reactive sulfhydryl necessary for function in covalently binding nascent fatty acids during biosynthesis. In Plasmodium falciparum, the causative agent of the most lethal form of malaria, fatty acid biosynthesis occurs in the apicoplast organelle during the liver stage of the parasite life cycle. During the blood stage, fatty acid biosynthesis is inactive and the redox state of the apicoplast has not been determined. We solved the crystal structure of ACP from P. falciparum in reduced and disulfide-linked forms, and observe the surprising result that the disulfide in the PfACP cross-linked dimer is sequestered from bulk solvent in a tight molecular interface. We assessed solvent accessibility of the disulfide with small molecule reducing agents and found that the disulfide is protected from BME but less so for other common reducing agents. We examined cultured P. falciparum parasites to determine which form of PfACP is prevalent during the blood stages. We readily detected monomeric PfACP in parasite lysate, but do not observe the disulfide-linked form, even under conditions of oxidative stress. To demonstrate that PfACP contains a free sulfhydryl and is not acylated or in the apo state, we treated blood stage parasites with the disulfide forming reagent diamide. We found that the effects of diamide are reversed with reducing agent. Together, these results suggest that the apicoplast is a reducing compartment, as suggested by models of P. falciparum metabolism, and that PfACP is maintained in a reduced state during blood stage growth.
Authors:
John R Gallagher; Sean T Prigge
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Proteins     Volume:  78     ISSN:  1097-0134     ISO Abbreviation:  Proteins     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-12     Completed Date:  2010-03-25     Revised Date:  2014-09-10    
Medline Journal Info:
Nlm Unique ID:  8700181     Medline TA:  Proteins     Country:  United States    
Other Details:
Languages:  eng     Pagination:  575-88     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Acyl Carrier Protein / chemistry*,  genetics,  metabolism
Crystallography, X-Ray
Disulfides / chemistry*,  metabolism
Dithiothreitol / metabolism
Merozoites / metabolism
Models, Molecular
Oxidation-Reduction
Plasmodium falciparum / chemistry*,  genetics,  metabolism
Protein Conformation
Grant Support
ID/Acronym/Agency:
R01 AI065853/AI/NIAID NIH HHS; R01 AI065853/AI/NIAID NIH HHS; R01 AI065853-04/AI/NIAID NIH HHS
Chemical
Reg. No./Substance:
0/Acyl Carrier Protein; 0/Disulfides; T8ID5YZU6Y/Dithiothreitol
Comments/Corrections

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