Aggregatibacter actinomycetemcomitans leukotoxin is post-translationally modified by addition of either saturated or hydroxylated fatty acyl chains
| Autor: | Kathleen Boesze-Battaglia, Angela C. Brown, Edward T. Lally, David W. Speicher, Hsin-Yao Tang, Karen P. Fong, Irene R. Kieba |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Microbiology (medical)
Virulence Factors Acylation Immunology Lysine Bacterial Toxins Exotoxins Peptide medicine.disease_cause Microbiology Aggregatibacter actinomycetemcomitans Article Mass Spectrometry law.invention chemistry.chemical_compound law medicine General Dentistry Escherichia coli chemistry.chemical_classification Chemistry Selected reaction monitoring Recombinant Proteins Biochemistry Recombinant DNA lipids (amino acids peptides and proteins) Post-translational protein modification Protein Processing Post-Translational Acyl group |
| Popis: | Aggregatibacter actinomycetemcomitans, a common inhabitant of the human upper aerodigestive tract, produces a repeat in toxin (RTX), leukotoxin (LtxA). The LtxA is transcribed as a 114-kDa inactive protoxin with activation being achieved by attachment of short chain fatty acyl groups to internal lysine residues. Methyl esters of LtxA that were isolated from A. actinomycetemcomitans strains JP2 and HK1651 and subjected to gas chromatography/mass spectrometry contained palmitoyl (C16:0, 27-29%) and palmitolyl (C16:1 cis Δ9, 43-44%) fatty acyl groups with smaller quantities of myristic (C14:0, 14%) and stearic (C18:0, 12-14%) fatty acids. Liquid chromatography/mass spectrometry of tryptic peptides from acylated and unacylated recombinant LtxA confirmed that Lys(562) and Lys(687) are the sites of acyl group attachment. During analysis of recombinant LtxA peptides, we observed peptide spectra that were not observed as part of the RTX acylation schemes of either Escherichia coliα-hemolysin or Bordetella pertussis cyclolysin. Mass calculations of these spectra suggested that LtxA was also modified by the addition of monohydroxylated forms of C14 and C16 acyl groups. Multiple reaction monitoring mass spectrometry identified hydroxymyristic and hydroxypalmitic acids in wild-type LtxA methyl esters. Single or tandem replacement of Lys(562) and Lys(687) with Arg blocks acylation, resulting in a75% decrease in cytotoxicity when compared with wild-type toxin, suggesting that these post-translational modifications are playing a critical role in LtxA-mediated target cell cytotoxicity. |
| Databáze: | OpenAIRE |
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