TY - JOUR

T1 - Inhibitory serpins from wheat grain with reactive centers resembling glutamine-rich repeats of prolamin storage proteins. Cloning and characterization of five major molecular forms

AU - Oøstergaard, Henrik

AU - Rasmussen, Soøren K.

AU - Roberts, Thomas H.

AU - Hejgaard, Joørn

PY - 2000/10/27

Y1 - 2000/10/27

N2 - Genes encoding proteins of the serpin superfamily are widespread in the plant kingdom, but the properties of very few plant serpins have been studied, and physiological functions have not been elucidated. Six distinct serpins have been identified in grains of hexaploid bread wheat (Triticum aestivum L.) by partial purification and amino acid sequencing. The reactive centers of all but one of the serpins resemble the glutamine-rich repetitive sequences in prolamin storage proteins of wheat grain. Five of the serpins, classified into two protein Z subfamilies, WSZ1 and WSZ2, have been cloned, expressed in Escherichia coli, and purified. Inhibitory specificity toward 17 proteinases of mammalian, plant, and microbial origin was studied. All five serpins were suicide substrate inhibitors of chymotrypsin and cathepsin G. WSZ1a and WSZ1b inhibited at the unusual reactive center P1-P1' Gln-Gln, and WSZ2b at P2-P1 Leu-Arg - one of two overlapping reactive centers. WSZ1c with P1-P1' Leu-Gln was the fastest inhibitor of chymotrypsin (k(a) = 1.3 x 106 M-1 s-1). WSZ1a was as efficient an inhibitor of chymotrypsin as WSZ2a (k(a) ~105 M-1 s-1), which has P1-P1' Leu-Ser - a reactive center common in animal serpins. WSZ2b inhibited plasmin at P1-P1' Arg-Gln (k(a) ~103 M-1 s-1). None of the five serpins inhibited Bacillus subtilisin A, Fusarium trypsin, or two subtilisin-like plant serine proteinases, hordolisin from barley green malt and cucumisin D from honeydew melon. Possible functions involving interactions with endogenous or exogenous proteinases adapted to prolamin degradation are discussed.

AB - Genes encoding proteins of the serpin superfamily are widespread in the plant kingdom, but the properties of very few plant serpins have been studied, and physiological functions have not been elucidated. Six distinct serpins have been identified in grains of hexaploid bread wheat (Triticum aestivum L.) by partial purification and amino acid sequencing. The reactive centers of all but one of the serpins resemble the glutamine-rich repetitive sequences in prolamin storage proteins of wheat grain. Five of the serpins, classified into two protein Z subfamilies, WSZ1 and WSZ2, have been cloned, expressed in Escherichia coli, and purified. Inhibitory specificity toward 17 proteinases of mammalian, plant, and microbial origin was studied. All five serpins were suicide substrate inhibitors of chymotrypsin and cathepsin G. WSZ1a and WSZ1b inhibited at the unusual reactive center P1-P1' Gln-Gln, and WSZ2b at P2-P1 Leu-Arg - one of two overlapping reactive centers. WSZ1c with P1-P1' Leu-Gln was the fastest inhibitor of chymotrypsin (k(a) = 1.3 x 106 M-1 s-1). WSZ1a was as efficient an inhibitor of chymotrypsin as WSZ2a (k(a) ~105 M-1 s-1), which has P1-P1' Leu-Ser - a reactive center common in animal serpins. WSZ2b inhibited plasmin at P1-P1' Arg-Gln (k(a) ~103 M-1 s-1). None of the five serpins inhibited Bacillus subtilisin A, Fusarium trypsin, or two subtilisin-like plant serine proteinases, hordolisin from barley green malt and cucumisin D from honeydew melon. Possible functions involving interactions with endogenous or exogenous proteinases adapted to prolamin degradation are discussed.

UR - http://www.scopus.com/inward/record.url?scp=0034721763&partnerID=8YFLogxK

U2 - 10.1074/jbc.M004633200

DO - 10.1074/jbc.M004633200

M3 - Journal article

C2 - 10874043

AN - SCOPUS:0034721763

VL - 275

SP - 33272

EP - 33279

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 43

ER -