PLANT PHYSIOLOGY , Vol 107, Issue 3 933-941, Copyright © 1995 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
RNA-Binding Characteristics of a Ribonucleoprotein from Spinach Chloroplast
I. Lisitsky, V. Liveanu and G. Schuster
Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
A chloroplast (nuclear-encoded) RNA-binding protein (28RNP) was previously
purified from spinach (Spinacia oleracea). This 28RNP was found to be the
major RNA-binding protein co-purified during the isolation scheme of
3[prime] end RNA-processing activity of several chloroplastic genes. To
learn more about the possible involvement of 28RNP in the 3[prime] end
RNA-processing event, we investigated the RNA-binding properties and the
location of the protein in the chloroplast. We found that recombinant
Escherichia coliexpressed 28RNP binds with apparently the same affinity to
every chloroplastic 3[prime] end RNA that was analyzed, as well as to RNAs
derived from the 5[prime] end or the coding region of some chloroplastic
genes. Differences in the RNA-binding affinities for some chloroplastic
3[prime] end RNAs were observed when the recombinant 28RNP was compared
with the "native" 28RNP in the chloroplast-soluble protein extract. In
addition, we found that the 28RNP is not associated with either
thylakoid-bound or soluble polysomes in which a great portion of the
chloroplast rRNA and mRNA are localized. These results suggest that the
native 28RNP binds specifically to certain RNA molecules in the chloroplast
in which other components (possibly proteins) and/or posttranslational
modifications are involved in determining RNA-binding specificity of the
28RNP.
