Multiple isoforms of Pisum trypsin inhibitors result from modification of two primary gene products

Abstract

Characterization of Pisum (pea) seed trypsin inhibitors (TI) and their corresponding cDNAs indicates that the pea TI gene family contains two genes. The existence of multiple TI isoforms can be attributed to post-translational modifications of primary gene products. Post-translational processing at the Cterminus during the desiccation stage of seed development results in the appearance of TI isoforms with increased affinity for the target enzyme, trypsin.

The effect of germination on seed trypsin inhibitors in Vicia faba and Cicer arietinum

“…18 In pea (Pisum sativum) seeds, processing at both amino and carboxy terminal ends of proteins has been implicated in the derivation of multiple TI isoforms with altered activity. 19 Further processing events could result in the isoform changes detected during germination in Vicia and Cicer. It is possible that proteases involved in degradation of, for example, the major legumin subunits as seen in V faba (Fig 3) could be responsible for the generation of TI charge variants with or without concomitant changes in overall activity.…”

Combinatorial variation in coding and promoter sequences of genes at the Tri locus in Pisum sativum accounts for variation in trypsin inhibitor activity in seeds

“…The cv. Birte was chosen to represent peas with low seed TIA (Muel et al 1998), since the expression of TI genes in this line had been studied previously (Domoney et al 1995;Welham et al 1998). Seeds of the three cvs., from the INRA-Dijon P. sativum germplasm collection, were grown in a greenhouse, and plants were sprayed for protection against insects.…”

“…1. The reverse primers were based on cDNAs corresponding to the genes for the major seed TI (Domoney et al 1995). The first PCR was performed in a volume of 20 ll, and the following PCR contained 2 ll of the 50-fold diluted product from the first reaction.…”

“…Frisson (240-300 mg), Victor (300-360 mg) and Birte (500-600 mg). Total RNA was prepared from freeze-dried seeds and analysed on Northern blots as previously described (Domoney et al 1995). RNA (3 lg per sample) was glyoxalated, fractionated by gel electrophoresis and blotted to nitrocellulose.…”

“…A genetic locus, Tri, on linkage group V, contains the structural genes encoding the major seed TI (Domoney et al 1994(Domoney et al , 1995. These genes have also been implicated in plant responses to water-deficit stress (Welham and Domoney 2000).…”