title: Escherichia coli alpha-hemolysin (HlyA) is heterogeneously acylated in vivo with 14-, 15-, and 17-carbon fatty acids.
abstract: alpha-Hemolysin (HlyA) is a secreted protein virulence factor observed in certain uropathogenic strains of Escherichia coli. The active, mature form of HlyA is produced by posttranslational modification of the protoxin that is mediated by acyl carrier protein and an acyltransferase, HlyC. We have now shown using mass spectrometry that these modifications, when observed in protein isolated in vivo, consist of acylation at the epsilon-amino groups of two internal lysine residues, at positions 564 and 690, with saturated 14- (68%), 15- (26%), and 17- (6%) carbon amide-linked side chains. Thus, HlyA activated in vivo consists of a heterogeneous family of up to nine different covalent structures, and the substrate specificity of the HlyC acyltransferase appears to differ from that of the closely related CyaC acyltransferase expressed by Bordetella pertussis.
authors.affiliation: Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, USA.
authors.forename: K B
authors.initials: KB
authors.lastname: Lim
authors.forename: C R
authors.initials: CR
authors.lastname: Walker
authors.forename: L
authors.initials: L
authors.lastname: Guo
authors.forename: S
authors.initials: S
authors.lastname: Pellett
authors.forename: J
authors.initials: J
authors.lastname: Shabanowitz
authors.forename: D F
authors.initials: DF
authors.lastname: Hunt
authors.forename: E L
authors.initials: EL
authors.lastname: Hewlett
authors.forename: A
authors.initials: A
authors.lastname: Ludwig
authors.forename: W
authors.initials: W
authors.lastname: Goebel
authors.forename: R A
authors.initials: RA
authors.lastname: Welch
authors.forename: M
authors.initials: M
authors.lastname: Hackett
mesh_terms: D000215:Acylation; D000217:Acyltransferases; D001426:Bacterial Proteins / Q000378:metabolism*; D001427:Bacterial Toxins / Q000378:metabolism*; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D005227:Fatty Acids / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D006460:Hemolysin Proteins / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D029968:Escherichia coli Proteins; D005227:Fatty Acids; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D000217:Acyltransferases; C092237:HlyC protein, E coli