Proteolytic activity in the maize pollen wall

Abstract

S. 1996. Proteolylic activity in the maize pollen wali, -Physiol. Plant, 98: i72-17S, A new protease from maize {Zea may.'; L,) pollen is described. It was purified using gel filtration, ion exchange and high performance liquid ehromatography, SDS-PAGE and HPLC showed that the enzyme ha,s a dimeric stracture of M, ca 60 000, Inhibitor investigations indicated an aspartic acid residue in it,s active site. The optimum pH for maize pollen aspartic proteinase activity was 5,6, and the optimum temperature was 45°C, The enzyme is easily eluted from the pollen grains and, as confimied by enzymoblotting after isoelectric focusing, it is located in the pollen wall. Similar to metallo-proteinases, its activity is inhibited by Zn'*, The pi value for purified aspartic proteinase, as estimated after IEF, was 5,0, Two-dimensional electrophoresis analysis of proteins eluted from maize pistils suggests that the enzyme digests the proteins and may be involved in pollen-tuix germination. The properties of serine and aspartic proteinases from maize pollen are compared.

A survey of proteinases active during meiotic development

“…The latter of these might serve to properly sculpt the pollen surface and play a role in pollen hydration, germination or even pollination speci®city. In support of this contention, it has recently been demonstrated that some of the major protein components of Brassica napus pollen are derived from extracellular cleavage of precursor proteins (Murphy and Ross 1998), that proteolytic activity can be detected in the maize pollen wall (Radlowski et al 1996), and that the LIM9 proteinase is secreted into the anther locule (Taylor et al 1997). The second potential function for proteinases centers on their presumptive role in meiotic purging (Dickinson 1987).…”

“…Partial inhibition of proteinase activity has been reported for several plant proteinases (e.g. Radlowski et al 1996;Disterano et al 1997).…”

Impact of cysteine proteinase inhibition in midgut fluid and oral secretion on fecundity and pollen consumption of western corn rootworm (Diabrotica virgifera virgifera)

“…6). In vitro addition of fresh corn pollen without E-64 into the proteinase reaction mixture did not affect the overall proteinase activity (data not shown), although the presence of proteinases in corn pollen has been reported (Radlowski et al, 1996). It is suggested that the reduction of E-64 potency after incubation with corn pollen may be due to interaction with other chemical or enzymatic factors in the pollen.…”

Effects of interaction between pollen coat eluates and pistil at the molecular level in self-compatible and self-incompatible plants ofLolium multiflorum Lam.

“…In Brassica napus new peptides appeared, probably as a result of protein-protein interaction after mixing crude extracts from pistils and pollen (Doughty et al 1993). New peptides formed after this interaction may also be the effects of protease activities, which was previously suggested by Rad³owski et al (1996) and subsequently by Kalinowski et al (2001). In stigmas of grasses after pollination the intensity of protein synthesis was observed (Linskens 1973(Linskens , 1976.…”

“…However, the obtained data show an exceptionally poor picture of the low-molecularweight fraction on chromatograms for stigmas both treated and untreated with pollen enzymes. This fact might prove once again that pollen proteases have high specific activities and hydrolyze a protein chain only at 1-2 amino acids (Matheson et al 1995;Rad³owski et al 1996). It explains also the appearance of new polypeptides on 2-D electrophoregrams.…”