PLANT PHYSIOLOGY , Vol 105, Issue 4 1167-1177, Copyright © 1994 by American Society of Plant Biologists
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MOLECULAR BIOLOGY AND GENE REGULATION |
Ribosomes Pause during the Expression of the Large ATP Synthase Gene Cluster in Spinach Chloroplasts
N. E. Stollar, J. K. Kim and M. J. Hollingsworth
Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York 14260
The large ATP synthase gene cluster from spinach (Spinacia oleracea)
chloroplasts encodes five genes, the last four of which encode subunits of
the ATP synthase complex. In preliminary experiments (J.K. Kim, M.J.
Hollingsworth [1992] Anal Biochem 206: 183-188) it was shown that ribosomes
pause during translation of these open reading frames. We have examined
ribosome pausing in the four ATP synthase open reading frames of this gene
cluster to determine whether it could affect the final ratio of the ATP
synthase polypeptides derived from the cluster. Ribosome pauses were mapped
and found to be distributed in a nonuniform manner. We have quantitated the
relative extent of ribosome pausing within each open reading frame. There
is a general but not absolute correlation between the extent of ribosomal
pausing and the protein levels found within the ATP synthase complex. We
conclude that although it is not the sole factor, ribosome pausing may be a
significant posttranscriptional mechanism affecting the expression of the
large ATP synthase gene cluster in spinach chloroplasts.
