Bowman–Birk protease inhibitor from the seeds of Vigna unguiculata forms a highly stable dimeric structure

• Published in: Biochimica et biophysica acta Vol. 1774; no. 10; pp. 1264 - 1273
• Main Authors: Rao, K.N., Suresh, C.G.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2007
• Subjects: Amino Acid Sequence; Binding Sites; Bowman–Birk protease inhibitor; Crystallography, X-Ray; Dimerization; Fabaceae - enzymology; Fabaceae - genetics; Molecular Sequence Data; Plant protease inhibitor; Protein Structure, Quaternary; Protein–protein interaction; Trypsin Inhibitor, Bowman-Birk Soybean - chemistry; Trypsin Inhibitor, Bowman-Birk Soybean - metabolism; Trypsin Inhibitors - chemistry; Trypsin Inhibitors - metabolism; Vigna unguiculata; FPLC; BBI-Bowman; SDS-PAGE; BT; Bowman–Birk protease inhibitor; ES-MS; Vigna unguiculata; Plant protease inhibitor; PIs; Protein–protein interaction; NCS
• ISSN: 1570-9639; 0006-3002; 1878-1454; 1878-2434
• DOI: 10.1016/j.bbapap.2007.07.009

Different protease inhibitors including Bowman–Birk type (BBI) have been reported from the seeds of Vigna unguiculata. Protease isoinhibitors of double-headed Bowman–Birk type from the seeds of Vigna unguiculata have been purified and characterized. The BBI from Vigna unguiculata ( Vu-BBI) has been found to undergo self-association to form very stable dimers and more complex oligomers, by size-exclusion chromatography and SDS-PAGE in the presence of urea. Many BBIs have been reported to undergo self-association to form homodimers or more complex oligomers in solution. Only one dimeric crystal structure of a BBI (pea-BBI) is reported to date. We report the three-dimensional structure of a Vu-BBI determined at 2.5 Å resolution. Although, the inhibitor has a monomer fold similar to that found in other known structures of Bowman–Birk protease inhibitors, its quaternary structure is different from that commonly observed in this family. The structural elements responsible for the stability of monomer molecule and dimeric association are discussed. The Vu-BBI may use dimeric or higher quaternary association to maintain the physiological state and to execute its biological function.