title: Posttranslational maturation of the invasion acyl carrier protein of Salmonella enterica serovar Typhimurium requires an essential phosphopantetheinyl transferase of the fatty acid biosynthesis pathway.
abstract: Salmonella pathogenicity island 1 (SPI-1) carries genes required for the formation of a type 3 secretion system, which is necessary for the invasion process of Salmonella. Among the proteins encoded by SPI-1 is IacP, a homolog of acyl carrier proteins. Acyl carrier proteins are mainly involved in fatty acid biosynthesis, and they require posttranslational maturation by addition of a 4'-phosphopantetheine prosthetic group to be functional. In this study, we analyzed IacP maturation in vivo. By performing matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry analysis of intact purified proteins, we showed that IacP from Salmonella enterica serovar Typhimurium was matured by addition of 4'-phosphopantetheine to the conserved serine 38 residue. Therefore, we searched for the phosphopantetheinyl transferases in charge of IacP maturation. A bacterial two-hybrid approach revealed that IacP interacted with AcpS, an enzyme normally required for the maturation of the canonical acyl carrier protein (ACP), which is involved in fatty acid biosynthesis. The creation of a conditional acpS mutant then demonstrated that AcpS was necessary for the maturation of IacP. However, although IacP was similar to ACP and matured by using the same enzyme, IacP could not replace the essential function of ACP in fatty acid synthesis. Hence, the demonstration that IacP is matured by AcpS establishes a cross-connection between virulence and fatty acid biosynthesis pathways.
authors.affiliation: CNRS, Laboratoire d'Ingénierie des Systèmes Macromoléculaires (UMR 7255), Institut de Microbiologie de la Méditerranée, Marseille, France.
authors.forename: Julie P M
authors.initials: JP
authors.lastname: Viala
authors.forename: Rémy
authors.initials: R
authors.lastname: Puppo
authors.forename: Lætitia
authors.initials: L
authors.lastname: My
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Bouveret
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005227:Fatty Acids / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism*; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D005227:Fatty Acids; C419942:Spi1 protein, Salmonella; C082662:phosphopantetheinyl transferase; D017855:Transferases (Other Substituted Phosphate Groups)
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