FUNCTIONAL ANALYSIS OF MAIZE GROUP-1 POLLEN ALLERGENS

Project: Research project

Project Details

Description

DESCRIPTION (from the application): When grass pollen lands on the receptive
surface of the stigma, it begins to hydrate and secrete various proteins. Among
these is an antigenic protein known as the group-I grass pollenallergen. This
protein is a major cause of hay fever and asthma, afflicting ca. 25 percentof
the US population. We recently discovered that the group-I allergen from maize
pollen (called Zea ml) loosens the extracellular matrix (wall) of the grass
stigma. In this proposal, we outline several experimental approaches to
elucidate the structure, function, and evolutionary distribution of the group-I
allergens and related proteins, which we hypothesize aid pollen tube
penetration of the stigma and style. RNA and protein analyses will be used to
determine the temporal and spatial pattern of Zea ml expression and secretion.
Using a reverse genetics approach we have identified four maize lines with
transposon insertions in the Zea ml gene; these lines will be studied to learn
the phenotypic consequences of Zea ml gene disruption. We will take advantage
of the unusual physical properties of Zea ml to study how it acts to loosen the
cell wall, still an enigmatic problem. By X-ray analysis of Zea ml crystals, we
propose to solve its structure and to use this structure to investigate how the
protein interacts with the polymers of the extracellular matrix. By binding
assays we will define the substrates to which this protein binds. We will test
these ideas by site-directed mutagenesis of recombinant protein. We will also
attempt to identify peptides, monoclonal antibodies and oligosaccharides that
interfere with Zea ml activity, to be used as inhibitors of the biological
function of these proteins. To date, it appears that group-I grass pollen
allergens are found only in grasses. To evaluate the evolutionary distribution
of this protein, we will test pollen extracts from grasses, close relatives,
and more distant plant groups by means of activity and immunoblot assays.
Finally, we will leverage the insights gained from analysis of Zea ml to study
the function of group-Il and group-Ill grass pollen allergens, which show
significant sequence similarity with the carboxy terminus of group-I allergens.
StatusFinished
Effective start/end date12/15/0011/30/01

Funding

  • National Institute of General Medical Sciences: $192,211.00

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