title: Lectin genes in the Frankia alni genome.
abstract: Frankia alni strain ACN14a's genome was scanned for the presence of determinants involved in interactions with its host plant, Alnus spp. One such determinant type is lectin, proteins that bind specifically to sugar motifs. The genome of F. alni was found to contain 7 such lectin-coding genes, five of which were of the ricinB-type. The proteins coded by these genes contain either only the lectin domain, or also a heat shock protein or a serine-threonine kinase domain upstream. These lectins were found to have several homologs in Streptomyces spp., and a few in other bacterial genomes among which none in Frankia EAN1pec and CcI3 and two in strain EUN1f. One of these F. alni genes, FRAAL0616, was cloned in E. coli, fused with a reporter gene yielding a fusion protein that was found to bind to both root hairs and to bacterial hyphae. This protein was also found to modify the dynamics of nodule formation in A. glutinosa, resulting in a higher number of nodules per root. Its role could thus be to permit binding of microbial cells to root hairs and help symbiosis to occur under conditions of low Frankia cell counts such as in pioneer situations.
authors.affiliation: Ecologie Microbienne, UMR5557 CNRS, Universite Lyon, Universite Lyon1, 16 rue Dubois, 69622 Villeurbanne cedex, France. Petar.Pujic@univ-lyon1.fr
authors.forename: Petar
authors.initials: P
authors.lastname: Pujic
authors.forename: Pascale
authors.initials: P
authors.lastname: Fournier
authors.forename: Nicole
authors.initials: N
authors.lastname: Alloisio
authors.forename: Anne-Emmanuelle
authors.initials: AE
authors.lastname: Hay
authors.forename: Joelle
authors.initials: J
authors.lastname: Maréchal
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Anchisi
authors.forename: Philippe
authors.initials: P
authors.lastname: Normand
mesh_terms: D029661:Alnus / Q000382:microbiology; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D040161:Frankia / Q000235:genetics*; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D037102:Lectins / Q000235:genetics*; D010802:Phylogeny; D053204:Root Nodules, Plant / Q000382:microbiology; D013302:Streptomyces / Q000235:genetics; D013559:Symbiosis / Q000235:genetics
chemical_list: D037102:Lectins