title: Glucose and trehalose PTS permeases of Spiroplasma citri probably share a single IIA domain, enabling the spiroplasma to adapt quickly to carbohydrate changes in its environment.
abstract: Spiroplasma citri is a plant-pathogenic mollicute phylogenetically related to Gram-positive bacteria. Spiroplasma cells are restricted to the phloem sieve tubes and are transmitted from plant to plant by the leafhopper vector Circulifer haematoceps. In the plant sieve tubes, S. citri grows on glucose and fructose, whereas in the leafhopper haemolymph the spiroplasma must grow on trehalose, the major sugar in insects. Previous studies in this laboratory have shown that fructose utilization was a key factor of spiroplasmal pathogenicity. To further study the implication of sugar metabolism in the interactions of S. citri with its plant host and its leafhopper vector, genes encoding permease enzymes II (EII(Glc) and EII(Tre)) of the S. citri phosphoenolpyruvate : glucose and phosphoenolpyruvate : trehalose phosphotransferase systems (PTS) were characterized. Mapping studies revealed that the EII(Glc) complex was split into two distinct polypeptides, IIA(Glc) and IICB(Glc), encoded by two separate genes, crr and ptsG, respectively. As expected, S. citri polypeptides IIA(Glc) and IICB(Glc) were more phylogenetically related to their counterparts from Gram-positive than to those from Gram-negative bacteria. The trehalose operon consisted of three genes treR, treP and treA, encoding a transcriptional regulator, the PTS permease (EII(Tre)) and the amylase, respectively. However, in contrast to the fructose-PTS permease, which is encoded as a single polypeptide (IIABC(Fru)) containing the three domains A, B and C, the trehalose-PTS permease (IIBC(Tre)) lacks its own IIA domain. No trehalose-specific IIA could be identified in the spiroplasmal genome, suggesting that the IIBC(Tre) permease probably functions with the IIA(Glc) domain. In agreement with this statement, yeast two-hybrid system experiments revealed that the IIA(Glc) domain interacted not only with IIB(Glc) but also with the IIB(Tre) domain. The results are discussed with respect to the ability of the spiroplasma to adapt from the phloem sap of the host plant to the haemolymph and salivary gland cells of the insect vector.
authors.affiliation: UMR Génomique Développement et Pouvoir Pathogène, IBVM, Centre INRA de Bordeaux, 71 avenue Edouard Bourlaux, BP 81, 33883 Villenave d'Ornon Cedex, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: André
authors.affiliation: UMR Génomique Développement et Pouvoir Pathogène, IBVM, Centre INRA de Bordeaux, 71 avenue Edouard Bourlaux, BP 81, 33883 Villenave d'Ornon Cedex, France.
authors.forename: Walter
authors.initials: W
authors.lastname: Maccheroni
authors.affiliation: Laboratoire de Biologie Moléculaire et de Séquençage, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, IBGC, 146 rue Léo Saignat, BP 64, 33076 Bordeaux Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Doignon
authors.affiliation: UMR Génomique Développement et Pouvoir Pathogène, IBVM, Centre INRA de Bordeaux, 71 avenue Edouard Bourlaux, BP 81, 33883 Villenave d'Ornon Cedex, France.
authors.forename: Monique
authors.initials: M
authors.lastname: Garnier
authors.affiliation: UMR Génomique Développement et Pouvoir Pathogène, IBVM, Centre INRA de Bordeaux, 71 avenue Edouard Bourlaux, BP 81, 33883 Villenave d'Ornon Cedex, France.
authors.forename: Joël
authors.initials: J
authors.lastname: Renaudin
mesh_terms: D000818:Animals; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000737:chemistry; D005947:Glucose / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D010802:Phylogeny; D010944:Plants / Q000382:microbiology; D045642:Spiroplasma citri / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D014199:Trehalose / Q000378:metabolism*
chemical_list: D002241:Carbohydrates; D026901:Membrane Transport Proteins; D014199:Trehalose; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D005947:Glucose