The modular nodulins Nvf-28/32 of broad bean (Vicia faba L.): alternative exon combinations account for different modular structures.
The broad bean late nodulins, Nvf-28/32, are composed of two types of repetitively occurring sequence modules flanked by unique N- and C-terminal modules. Six isoforms of these nodulins were characterized by a specific modular structure resulting from a different individual order of repetitive sequence modules. A detailed analysis of genomic PCR fragments revealed that the repetitive modules and the N-terminal unique module exactly corresponded to exons, whereas the C-terminal module was specified by two exons. Since those exons encoding the repetitive modules missing in specific Nvf-28/32 isoforms were consistently present within genomic sequences, a post-transcriptional generation of VfNOD28/32 transcripts specifying six Nvf-28/32 nodulins was concluded. Using tissue-print hybridizations, these transcripts were localized in the interzone II-III and the nitrogen-fixing zone III of root nodules. From this and from cDNA-cDNA hybridizations demonstrating a comparable timing of expression of VfNOD28/32 and of leghemoglobin transcripts in root nodules, a function of the modular nodulins Nvf-28/32 in late developmental stages of broad bean nodules was inferred.
Küster
H
H
Lehrstuhl für Genetik, Universität Bielefeld, Germany.
Frühling
M
M
Pühler
A
A
Perlick
A M
AM
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D005091:Exons; D007887:Fabaceae / Q000235:genetics*; D018745:Genome, Plant; D017403:In Situ Hybridization; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D010946:Plants, Medicinal; D014158:Transcription, Genetic
D008565:Membrane Proteins; D010940:Plant Proteins; C045625:nodulin