Journal
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY
Volume 305, Issue 12, Pages C1240-C1245Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpcell.00279.2013
Keywords
biotin; heat shock protein 72; holocarboxylase synthetase; posttranslational modification; RANTES
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Funding
- University of Nebraska Agricultural Research Division
- National Institute of Diabetes and Digestive and Kidney Diseases [DK-063945, DK-077816]
- Hatch Act
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In a recent mass spectrometry screen, we identified 108 new proteins that were modified endogenously by covalent binding of biotin; members of the heat shock superfamily of proteins, including heat shock protein 72 (HSP72), were overrepresented among the biotinylated proteins. Mammals respond to infections by secreting extracellular HSP72 (eHSP72), which elicits an immune response. Here, using mass spectrometry and site-directed mutagenesis, we identified five biotinylation sites in HSP72. We used coimmunoprecipitation, mass spectrometry, and limited proteolysis assays to demonstrate that HSP72 interacts physically with the protein biotin ligase holocarboxylase synthetase (HLCS), leading to biotinylation of residues K112, K128 K348, K361, K415, and, probably, additional lysines. Finally, we demonstrated that HLCS-dependent biotinylation of eHSP72 increases expression of the chemokine regulated on activation normal T-expressed and presumably secreted (RANTES) by human embryonic kidney (HEK-293) cells. In conclusion, we report a novel endogenous modification of HSP72 and demonstrated that binding of biotin to eHSP72 prepares cells for a strong immune response.
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