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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Publications at this Location » Publication #126536
Title: SUBTILISIN-LIKE PROTEASES FROM SOYBEAN

Author
item BEILINSON, V - PURDUE UNIVERSITY BIOCHEM
item MOSKALENKO, O - PURDUE UNIVERSITY AGRY
item LIVINGSTONE, D - PURDUE UNIVERSITY AGRY
item REVERDATTO, S - PURDUE UNIVERSITY BIOCHEM
item JUNG, R - PIONEER
item Nielsen, Niels

Submitted to: Physiologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: Seed coats play a crucial role in seed development. Besides controlling the supply of nutrients required for seed fill, they play a protective role. While descriptive studies about the multiple layers of cells that compose seed coats exist for soybean, little information is available about the biochemical and physiological mechanisms by which seed coats fulfill their functions. In this report, a soybean gene that encodes a subtilisin-like protein (SLP) is described. Subtilisins are a large family of enzymes that degrade proteins, are widespread in nature, and carry out a myriad of important cellular functions. The small but related SLP family of proteins of plants has been implicated in important regulatory functions within the cell, and in cellular responses to pathogen invasion. The soybean SLP is located in spongy mesophyll cells of the seed coat, an interior layer of cells near the cotyledons and seed embryo. The soybean gene encoding the SLP in seed coats is part of a small gene family. This report also describes a second SLP from soybean. Its function is also unknown, but products from the second SLP gene are not found in the seed coat. The information is of academic interest to scientists interested in seed coat biology.

Technical Abstract: Two subtilisn-like proteases (SPL) were identified in soybean (Glycine max L. Merr.). The first, SLP-1, was localized in seed coats early in seed development, but became undetectable with anti-SLP-1 antibodies as seed fill progressed. A partial purification of SLP-1 was achieved using a three step chromatographic procedure. NH2-terminal sequence analysis of the partially purified enzyme permitted primers to be designed that were used to amplify cDNAs encoding SLP-1. A genomic clone encoding SLP-1 was also obtained. Characterization of the cDNA and partially purified SLP-1 revealed the initial translation product was an 82,694 Mw precursor. After removal of a signal peptide, the mature protein was formed by removal of an NH2-terminal propeptide. A COOH-terminal peptide also appeared to be removed from some of the protease molecules. DNA blot analysis suggested that at least one additional SLP gene was present in soybean. The second gene, SLP-2, was subsequently cloned and characterized. Although the coding regions for SLP-1 and SLP-2 were homologous, their promoters were quite divergent. RT-PCR revealed that SLP-2 message was found in the mature plant and in cotyledons of germinating seeds. Although SLP-2 mRNA could be identified in developing seeds, the message was at least an order of magnitude less abundant than that for SLP-1, and it was misspliced such that a chain termination event would preclude obtaining a product. As with SLPs from other organisms, the functions of the soybean proteases are unknown. However, SLP-1 is one of only a few proteins from soybean seed coats that have been described.