Expression of a Gene for Uricase II (Nodulin-35) in Cotyledons of Soybean Plants

A cDNA clone (URcot-35) was isolated from a soybean cotyledonary cDNA library using a cDNA clone (URnod-35) for nodule uricase II as a probe. URcot-35 was a 1,170-bp cDNA with an open reading frame that encoded a protein of putative 309 amino acids with a molecular mass of 35,137 Da. The nucleotide sequence of URcot-35 was identical to that of URnod-35. Expression of the URcot-35 gene in cotyledons was investigated by Northern dot-blot hybridization, by the reverse transcription-polymerase chain reaction with subsequent hybridization assays with the cDNA for nodule uricase II as a probe, and by immunoblotting analysis with a monoclonal antibody that was specific to nodule uricase II. The results suggested that the transcript of URcot-35 was present in developing cotyledons and that uricase II accumulated during the pod-filling stage. This is the first report of the isolation of cDNA for uricase II from non-symbiotic tissue and the results demonstrate that uricase II in soybean cotyledons is identical to that in soybean nodules.