title: Purification and characterization of four beta-expansins (Zea m 1 isoforms) from maize pollen.
abstract: Four proteins with wall extension activity on grass cell walls were purified from maize (Zea mays) pollen by conventional column chromatography and high-performance liquid chromatography. Each is a basic glycoprotein (isoelectric point = 9.1-9.5) of approximately 28 kD and was identified by immunoblot analysis as an isoform of Zea m 1, the major group 1 allergen of maize pollen and member of the beta-expansin family. Four distinctive cDNAs for Zea m 1 were identified by cDNA library screening and by GenBank analysis. One pair (GenBank accession nos. AY104999 and AY104125) was much closer in sequence to well-characterized allergens such as Lol p 1 and Phl p 1 from ryegrass (Lolium perenne) and Phleum pretense, whereas a second pair was much more divergent. The N-terminal sequence and mass spectrometry fingerprint of the most abundant isoform (Zea m 1d) matched that predicted for AY197353, whereas N-terminal sequences of the other isoforms matched or nearly matched AY104999 and AY104125. Highly purified Zea m 1d induced extension of a variety of grass walls but not dicot walls. Wall extension activity of Zea m 1d was biphasic with respect to protein concentration, had a broad pH optimum between 5 and 6, required more than 50 micro g mL(-1) for high activity, and led to cell wall breakage after only approximately 10% extension. These characteristics differ from those of alpha-expansins. Some of the distinctive properties of Zea m 1 may not be typical of beta-expansins as a class but may relate to the specialized function of this beta-expansin in pollen function.
authors.affiliation: Department of Biology, 208 Mueller Laboratory, 152 Davey Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Lian-Chao
authors.initials: LC
authors.lastname: Li
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Bedinger
authors.forename: Carol
authors.initials: C
authors.lastname: Volk
authors.forename: A Daniel
authors.initials: AD
authors.lastname: Jones
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Cosgrove
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D002473:Cell Wall / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D000432:Methanol; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D006109:Poaceae / Q000166:cytology / Q000378:metabolism; D011058:Pollen / Q000737:chemistry*; D011489:Protein Denaturation; D020033:Protein Isoforms / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D003313:Zea mays / Q000737:chemistry* / Q000166:cytology
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D006023:Glycoproteins; D010940:Plant Proteins; D020033:Protein Isoforms; C083547:Zea mI protein, Zea mays; C095825:expansin protein, plant; D000432:Methanol