Submitted to: Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 27, 2000
Publication Date: N/A
Interpretive Summary: Invertase is an important enzyme that converts photosynthesized sucrose to simple sugars which are then utilized into numerous metabolic processes in various parts of the plants. Scientists at the Crop Genetics & Environmental Research Unit (CGERU) in Gainesville, FL, have previously described two genes that code for two separate forms of this enzyme. Two additional genes are now described here in a collaborative research between CGERU, ARS, and Institute de Biotechnologie des Plantes, Orsay, France. The results also include the structural organization of the genes, an essential component of Plant Genome research. The structural details include the DNA sequences of the genes that provide clues to structure - function relationship, and basis for their precise regulation at appropriate time and space in the plant. These results will be useful in future attempts to engineer these genes for greater crop productivity.
Two maize putative cell wall invertase genes (Incw3 and Incw4) have been isolated by screening a genomic DNA library (Zea mays L. W22) using the cDNA probes encoding the two maize cell wall invertases Incw1 and Incw2. The Incw3 and Incw4 genes contain six exons/five introns and five exons/four introns respectively. The protein sequences deduced from both genes revealed a B-fructosidase motif and a cysteine catalytic site known to be conserved in invertase genes. A detailed analysis of the protein and nucleotide sequences provide evidence that the Incw3 and Incw4 genes encode putative cell wall invertases. Furthermore, the isoelectric point deduced from the Incw4 protein sequence suggested that the Incw4 gene may encode a unique type of cell wall invertase unbound in the apoplast. Gene expression studies using RT-PCR and in situ RT-PCR hybridization showed that the Incw3 expression is organ/tissue specific and developmentally regulated. In contrast, the Incw4 gene is constitutively expressed in all vegetative and reproductive tissues tested.