PLANT PHYSIOLOGY , Vol 115, Issue 4 1431-1442, Copyright © 1997 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Immunolocalization of PsNLEC-1, a Lectin-Like Glycoprotein Expressed in Developing Pea Nodules
P. Dahiya, I. V. Kardailsky and N. J. Brewin
Department of Genetics, John Innes Centre, Colney Lane, Norwich, NR4 7UH, United Kingdom
The pea (Pisum sativum) nodule lectin gene PsNlec1 is a member of the
legume lectin gene family that is strongly expressed in infected pea nodule
tissue. A full-length cDNA sequence of PsNlec1 was expressed in Escherichia
coli and a specific antiserum was generated from the purified protein.
Immunoblotting of material from isolated symbiosomes revealed that the
glycoprotein was present in two antigenic isoforms, PsNLEC-1A and
PsNLEC-1B. The N-terminal sequence of isoform A showed homology to an
eight-amino acid propeptide sequence previously identified from the cDNA
sequence of isoform B. In nodule homogenates the antiserum recognized an
additional fast-migrating band, PsNLEC-1C. Fractionation studies indicated
that PsNLEC-1C was associated with a 100,000g nodule membrane fraction,
suggesting an association with cytoplasmic membrane or vesicles. Immunogold
localization in pea nodule tissue sections demonstrated that the PsNLEC-1
antigen was present in the symbiosome compartment and also in the vacuole
but revealed differences in distribution between infected host cells in
different parts of the nodule. These data suggest that PsNLEC-1 is subject
to posttranslational modification and that the various antigenic isoforms
can be used to monitor membrane and vesicle targeting during symbiosome
development.