title: Two functionally distinctive phosphopantetheinyl transferases from amoeba Dictyostelium discoideum.
abstract: The life cycle of Dictyostelium discoideum is proposed to be regulated by expression of small metabolites. Genome sequencing studies have revealed a remarkable array of genes homologous to polyketide synthases (PKSs) that are known to synthesize secondary metabolites in bacteria and fungi. A crucial step in functional activation of PKSs involves their post-translational modification catalyzed by phosphopantetheinyl transferases (PPTases). PPTases have been recently characterized from several bacteria; however, their relevance in complex life cycle of protozoa remains largely unexplored. Here we have identified and characterized two phosphopantetheinyl transferases from D. discoideum that exhibit distinct functional specificity. DiAcpS specifically modifies a stand-alone acyl carrier protein (ACP) that possesses a mitochondrial import signal. DiSfp in contrast is specific to Type I multifunctional PKS/fatty acid synthase proteins and cannot modify the stand-alone ACP. The mRNA of two PPTases can be detected during the vegetative as well as starvation-induced developmental pathway and the disruption of either of these genes results in non-viable amoebae. Our studies show that both PPTases play an important role in Dictyostelium biology and provide insight into the importance of PPTases in lower eukaryotes.
authors.affiliation: National Institute of Immunology, New Delhi, India.
authors.forename: Divya R
authors.initials: DR
authors.lastname: Nair
authors.forename: Ratna
authors.initials: R
authors.lastname: Ghosh
authors.forename: Alzu
authors.initials: A
authors.lastname: Manocha
authors.forename: Debasisa
authors.initials: D
authors.lastname: Mohanty
authors.forename: Shweta
authors.initials: S
authors.lastname: Saran
authors.forename: Rajesh S
authors.initials: RS
authors.lastname: Gokhale
mesh_terms: D000213:Acyl Carrier Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055162:Biocatalysis; D004023:Dictyostelium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D004591:Electrophoresis, Polyacrylamide Gel; D064429:Fatty Acid Synthases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D055786:Gene Knockout Techniques; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008018:Life Cycle Stages / Q000235:genetics; D008969:Molecular Sequence Data; D048630:Polyketide Synthases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity; D017855:Transferases (Other Substituted Phosphate Groups) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000213:Acyl Carrier Protein; D001426:Bacterial Proteins; D007527:Isoenzymes; D015800:Protozoan Proteins; C082662:phosphopantetheinyl transferase; D048630:Polyketide Synthases; D064429:Fatty Acid Synthases; D017855:Transferases (Other Substituted Phosphate Groups)