| Literature References | 1. ANSARI, A.A., KIHARA, T.K. AND MARSH, D.G.
Immunochemical studies of Lolium perenne (rye grass) pollen allergens, Lol p
I, II and III.
J.IMMUNOL. 139 4034-4041 (1987).
2. ANSARI, A.A., SHENBAGAMURTHI, P. AND MARSH, D.G.
Complete primary structure of a Lolium perenne (perennial rye grass) pollen
allergen, Lol p III: comparison with known Lol p I and II sequences.
BIOCHEMISTRY 28 8665-8670 (1989).
3. ANSARI, A.A., FREIDHOFF, L.R AND MARSH, D.G.
Molecular genetics of human immune responsiveness to Lolium perenne (rye)
allergen, Lol p III.
INT.ARCH.ALLERGY APPL.IMMUNOL. 88 164-169 (1989).
4. ANSARI, A.A., FREIDHOFFF, L.R., MEYERS, D.A, BIAS, W.B. AND MARSH, D.G.
Human immune responsiveness to Lolium perenne pollen allergen Lol p III
HUM.IMMUNOL. 25 59-71 (1989).
5. ANSARI, A.A., SHINOMIYA, N., ZWOLLO, P. AND MARSH, D.G.
HLA-D gene studies in relation to immune responsiveness to a grass allergen
Lol p III.
IMMUNOGENETICS 33 24-32 (1991).
6. BASKAR, S., PARRONCHI, P., MOHAOATRA, S., ROMAGNANI, S. AND ANSARI, A.A.
Human T cell responses to purified pollen allergens of the grass, Lolium
perenne. Analysis of the relationship between structural homology and T cell
recognition.
J.IMMUNOL. 148 2378-2383 (1992).
7. FEDOROV, A.A., BALL, T., VALENTA, R. AND ALMO, S.C.
X-ray crystal structures of birch pollen profilin and Phl p 2.
INT.ARCH.ALLERGY IMMUNOL. 113 109-113 (1997).
8. DE MARINO, S., MORELLI, M.A.C., FRATERNALI, F., TAMBORINI, E., MUSCO, G.,
VRTALA, S., DOLECEK, C., AROSIO, P., VALENTA, R. AND PASTORE, A.
An immunoglobulin-like fold in a major plant allergen: the solution
structure of Phl p 2 from timothy grass pollen.
STRUCTURE 7 943-952 (1999).
|
| Documentation | Grass pollen allergy is a major human health problem throughout the world,
perennial ryegrass (Lolium perenne) being one of the more important species
causing such allergy. Several proteins from this grass pollen have been
characterised and used to study specific serum antibody responses in
individuals allergic to pollen proteins. Such individuals often show
concordant presence of serum antibodies to all three Lol p allergens. Most
(~95%) possess serum IgE and/or IgG antibodies to Lol p I, and ~45% have
antibodies to Lol p II and III. Both Lol p II and III are highly cross-
reactive with human, goat and rabbit antibodies. However, antibodies to
Lol p I are unique and do not cross-react with Lol p II and III [1-6].
The amino acid sequences of Lol p II and Lol p III are highly similar,
sharing 59% identity. Both have a region of amphipathicity (residues
61-67, Lol p III numbering) that might contain sites for binding to Ia
molecules or T cell receptors. This region is identical between Lol p II
and III, except for an Arg-Lys substitution, and could account for the DR3
association with responsiveness to both molecules [2,3]. However, although
Lol p II and III show significant structural similarities and antibody
cross reactivity, it is intriguing that only Lol p III is able to induce
significant T cell responses [6]. Also interesting is that immune response
to Lol p III is associated with DR5 (in addition to DR3), whereas no DR5
association is found in Lol p II. One possibility is that Lol p III has an
additional site that binds to the DR5 Ia molecule. Indeed, Lol p III
has a second highly amphipathic peptide (residues 24-30, RPGDTLA), which is
different and not amphipathic in Lol II [3]. Moreover, comparison of the
sequences of DRB gene products has shown that the first hypervariable
region (residues 9-13) of DR3 and DR5, and no other region, contains the
sequence EYSTSTS. It is thought that this sequence in the DR beta 1
polypeptide chain is associated with the immune responsiveness to the
allergen Lol p III [4]. In addition, both allergens share similar structure
with an antibody-binding fragment for Lol p I. However, Lol p II appears to
contain unique Ia recognition sites not shared with Lol p II and III. This
could explain why Ab responses to the three allergens are associated with
DR3 and why most Lol p II and III responders are also Lol p I responders,
but Lol p I responders are not necessarily Lol p II and III responders [1].
The structure of allergen Phl p 2 from Timothy grass has been determined to
1.9A by X-ray crystallography [7], and more recently by NMR [8]. The protein
contains mainly beta structures typical of the immunoglobulin-like fold.
LOLP2ALLERGN is a 4-element fingerprint that provides a signature for the
pollen allergen Lol p II family. The fingerprint was derived for an initial
alignment of 6 sequences: the motifs were drawn from conserved regions
largely spanning the C-terminal portion of the alignment - motif 1 encodes
beta-strand 3; motif 2 includes strand 6; motif 3 spans strand 7; and motif
4 includes strand 8. A single iteration on SPTR39_17f was required to reach
convergence, no further sequences being identified beyond the starting set.
|