title: The broad bean gene VfNOD32 encodes a nodulin with sequence similarities to chitinases that is homologous to (alpha/beta)8-barrel-type seed proteins.
abstract: Nodulin gene transcripts isolated from a broad bean (Vicia faba L.) root nodule cDNA library and designated VfNOD32 are detectable in the nitrogen-fixing zone III of nodules and in much smaller amounts in flowers. In nodules, these transcripts are detectable for the first time 7 d after inoculation, at least 1 d before leghemoglobin gene transcription starts. Two putative full-length cDNAs representing different transcript sequences of 92.5% identity were sequenced. The corresponding broad bean genes were termed VfNOD32-A1 and VfNOD32-A2, and the encoded proteins were termed Nvf32-A1 and Nvf32-A2. The derived amino acid sequences of the Nvf32 proteins are highly homologous to the Vicia narbonensis (alpha/beta)8-barrel seed protein narbonin. Considering this homology, Nvf32 is assumed to have a similar structure consisting of beta-sheets forming a central barrel surrounded by alpha-helices. The two Nvf32 sequences also contain two conserved amino acid motifs that are characteristic of class-III chitinases. Several amino acids demonstrated to be essential for chitinase activity are conserved in both regions, whereas one essential glutamic acid was changed to glycine in the Nvf32-A1 isoform but not in the Nvf32-A2 isoform.
authors.affiliation: Universität Bielefeld, Lehrstuhl für Genetik, Germany.
authors.forename: A M
authors.initials: AM
authors.lastname: Perlick
authors.forename: M
authors.initials: M
authors.lastname: Frühling
authors.forename: G
authors.initials: G
authors.lastname: Schröder
authors.forename: S C
authors.initials: SC
authors.lastname: Frosch
authors.forename: A
authors.initials: A
authors.lastname: Pühler
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D002688:Chitinases / Q000235:genetics; D017124:Conserved Sequence; D018076:DNA, Complementary; D007887:Fabaceae / Q000235:genetics*; D015723:Gene Library; D017343:Genes, Plant; D005916:Globulins / Q000235:genetics; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010940:Plant Proteins / Q000235:genetics*; D014674:Plant Proteins, Dietary / Q000235:genetics; D010946:Plants, Medicinal; D012333:RNA, Messenger / Q000302:isolation & purification; D018749:RNA, Plant / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D013559:Symbiosis; D014018:Tissue Distribution
chemical_list: D018076:DNA, Complementary; D005916:Globulins; D008565:Membrane Proteins; D010940:Plant Proteins; D014674:Plant Proteins, Dietary; D012333:RNA, Messenger; D018749:RNA, Plant; C066193:narbonin; C045625:nodulin; D002688:Chitinases