Journal article
Aggregatibacter actinomycetemcomitans Leukotoxin Utilizes a Cholesterol Recognition/Amino Acid Consensus Site for Membrane Association
The Journal of biological chemistry, v 288(32), pp 23607-23621
09 Aug 2013
PMID: 23792963
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
Aggregatibacter actinomycetemcomitans produces a repeats-in-toxin (RTX) leukotoxin (LtxA) that selectively kills human immune cells. Binding of LtxA to its β2 integrin receptor (lymphocyte function-associated antigen-1 (LFA-1)) results in the clustering of the toxin·receptor complex in lipid rafts. Clustering occurs only in the presence of LFA-1 and cholesterol, and LtxA is unable to kill cells lacking either LFA-1 or cholesterol. Here, the interaction of LtxA with cholesterol was measured using surface plasmon resonance and differential scanning calorimetry. The binding of LtxA to phospholipid bilayers increased by 4 orders of magnitude in the presence of 40% cholesterol relative to the absence of cholesterol. The affinity was specific to cholesterol and required an intact secondary structure. LtxA contains two cholesterol recognition/amino acid consensus (CRAC) sites; CRAC336 (333LEEYSKR339) is highly conserved among RTX toxins, whereas CRAC503 (501VDYLK505) is unique to LtxA. A peptide corresponding to CRAC336 inhibited the ability of LtxA to kill Jurkat (Jn.9) cells. Although peptides corresponding to both CRAC336 and CRAC503 bind cholesterol, only CRAC336 competitively inhibited LtxA binding to this sterol. A panel of full-length LtxA CRAC mutants demonstrated that an intact CRAC336 site was essential for LtxA cytotoxicity. The conservation of CRAC336 among RTX toxins suggests that this mechanism may be conserved among RTX toxins.
Background: A repeats-in-toxin (RTX) leukotoxin and its integrin receptor aggregate in cholesterol-rich lipid rafts.
Results: The affinity of the toxin to cholesterol is driven by a cholesterol recognition/amino acid consensus (CRAC) motif.
Conclusion: Leukotoxin cytotoxicity is regulated by the CRAC motif.
Significance: Other RTX toxins contain this CRAC motif, suggesting a role for cholesterol recognition in RTX cytolysis.
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Details
- Title
- Aggregatibacter actinomycetemcomitans Leukotoxin Utilizes a Cholesterol Recognition/Amino Acid Consensus Site for Membrane Association
- Creators
- Angela C. Brown - University of PennsylvaniaNataliya V. Balashova - University Hospital, NewarkRichard M. Epand - McMaster UniversityRaquel F. Epand - McMaster UniversityAlvina Bragin - University of PennsylvaniaScott C. Kachlany - University Hospital, NewarkMichael J. Walters - From the Departments of Pathology andYurong Du - From the Departments of Pathology andKathleen Boesze-Battaglia - University of PennsylvaniaEdward T. Lally - From the Departments of Pathology and
- Publication Details
- The Journal of biological chemistry, v 288(32), pp 23607-23621
- Publisher
- Elsevier
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemical and Biological Engineering
- Web of Science ID
- WOS:000330598200064
- Scopus ID
- 2-s2.0-84881399993
- Other Identifier
- 991020950450004721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Biochemistry & Molecular Biology