Characterization of the genes for two soybean aspartic proteinases and analysis of their different tissue-dependent expression

Abstract

We isolated and characterized two cDNAs for aspartic proteinases (APs; EC 3.4.23) in soybean [Glycine max (L.) Merr.]. The encoded enzymes, soyAP1 and soyAP2, share 55% amino acid sequence identity. Northern analysis demonstrated that soyAP1 is expressed specifically in seeds, especially in dry seeds, while the expression of soyAP2 takes place in various tissues such as roots, stems, leaves and flowers, but not in dry seeds. SoyAP1 is highly expressed even at an early stage of germination, with a subsequent decrease in expression intensity. In contrast, the soyAP2 mRNA level increases 48 h after imbibition. To elucidate the physiological functions of soyAPs, we investigated the localization of soyAP expression in seeds germinating for 48 h at 25 degrees C. SoyAP1 shows cell-type-specific expression in sieve tube cells of the hypocotyl. At the root tip, soyAP1 is expressed in immature tracheary elements and sieve tube cells, and its expression pattern changes with distance from the tip; strong signals observed throughout phloem converge gradually to sieve tube cells, whereas those observed in tracheary elements disappear while the elements are still immature. On the other hand, soyAP2 signals were detected broadly in the boundary region between the cortex and the central cylinder. These results suggest that soyAP1 and soyAP2 are functionally different from each other.

Plant-specific insertions in the soybean aspartic proteinases, soyAP1 and soyAP2, perform different functions of vacuolar targeting

“…Previously, we reported the two soybean APs, soyAP1 expressed in dry seed and soyAP2 expressed in a variety of vegetative tissues (Terauchi et al, 2004). As soyAP1 mRNA differs from soyAP2 mRNA in terms of period-and tissue-specific expression, these two enzymes are expected to have different patterns of intracellular localization.…”

Proteolysis in the Subtropical Woody Tree <i>Anadenanthera colubrina</i> (Angico) Seeds during and after Germination

“…Phytepsins were also indirectly associated with germination in soy [44], buckwheat [43], Arabidopsis [45], wheat [41] and Araucaria [46].…”

“…However, the amino acids sequence from plant APs has 45% of homology with animal cathepsin-D (EC 3.4.23.5) [44]. Indeed, cathepsin-D is an endo-AP classified as member of A1 family (pepsin, phytepsin; MEROPS classification), which are active at acid pH and inhibited by pepstatin.…”

“…In addition, two or more cDNAs for different APs were obtained from dry seeds and during germination in buckwheat [43], wheat [41], soybean [44] and Arabidopsis [45], as well as aspartyl activity was observed during seed germination in Araucaria megagametophyte [46].…”

Influence of air temperature on proteinase activity and beverage quality in Coffea arabica

“…CaAP2 and CcAP2 belong to the peptidase A1 family, and some of their homologs have been reported as responsive to wounding or pathogen infection and are expressed in different tissues such as leaves, roots and seeds (Asakura et al 1995, Schaller & Ryan 1996, Terauchi et al 2004, Guevara et al 2005, Huang et al 2009). CaAP2 was not signifi cantly differentially expressed between mature and immature endosperm or between plants grown at different sites.…”