title: Involvement of a minimal actin-binding region of Spiroplasma citri phosphoglycerate kinase in spiroplasma transmission by its leafhopper vector.
abstract: BACKGROUND
  Spiroplasma citri is a wall-less bacterium that colonizes phloem vessels of a large number of host plants. Leafhopper vectors transmit S. citri in a propagative and circulative manner, involving colonization and multiplication of bacteria in various insect organs. Previously we reported that phosphoglycerate kinase (PGK), the well-known glycolytic enzyme, bound to leafhopper actin and was unexpectedly implicated in the internalization process of S. citri into Circulifer haematoceps cells.
  
  
  RESULTS
  In an attempt to identify the actin-interacting regions of PGK, several overlapping PGK truncations were generated. Binding assays, using the truncations as probes on insect protein blots, revealed that the actin-binding region of PGK was located on the truncated peptide designated PGK-FL5 containing amino acids 49-154. To investigate the role of PGK-FL5-actin interaction, competitive spiroplasma attachment and internalization assays, in which His(6)-tagged PGK-FL5 was added to Ciha-1 cells prior to infection with S. citri, were performed. No effect on the efficiency of attachment of S. citri to leafhopper cells was observed while internalization was drastically reduced. The in vivo effect of PGK-FL5 was confirmed by competitive experimental transmission assays as injection of PGK-FL5 into S. citri infected leafhoppers significantly affected spiroplasmal transmission.
  
  
  CONCLUSIONS
  These results suggest that S. citri transmission by its insect vector is correlated to PGK ability to bind actin.
authors.affiliation: INRA and Université Bordeaux UMR 1332 Biologie du Fruit et Pathologie, Villenave d'Ornon, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Labroussaa
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Dubrana
authors.forename: Nathalie
authors.initials: N
authors.lastname: Arricau-Bouvery
authors.forename: Laure
authors.initials: L
authors.lastname: Béven
authors.forename: Colette
authors.initials: C
authors.lastname: Saillard
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004199:Disease Vectors; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000201:enzymology / Q000235:genetics / Q000382:microbiology / Q000635:transmission*; D006430:Hemiptera / Q000382:microbiology*; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D010735:Phosphoglycerate Kinase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D054730:Protein Interaction Domains and Motifs / Q000235:genetics / Q000502:physiology*; D045642:Spiroplasma citri / Q000201:enzymology* / Q000235:genetics / Q000502:physiology
chemical_list: D000199:Actins; D008840:Microfilament Proteins; D010735:Phosphoglycerate Kinase