Stollar N E, Kim J K, Hollingsworth M J
Department of Biological Sciences, State University of New York at Buffalo 14260.
Plant Physiol. 1994 Aug;105(4):1167-77. doi: 10.1104/pp.105.4.1167.
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.
菠菜（Spinacia oleracea）叶绿体中的大型ATP合酶基因簇编码五个基因，其中后四个基因编码ATP合酶复合体的亚基。在初步实验中（J.K. Kim，M.J. Hollingsworth [1992] Anal Biochem 206: 183 - 188）表明，核糖体在这些开放阅读框的翻译过程中会暂停。我们研究了该基因簇中四个ATP合酶开放阅读框中的核糖体暂停情况，以确定其是否会影响该基因簇衍生的ATP合酶多肽的最终比例。核糖体暂停位点被定位，发现其分布不均匀。我们对每个开放阅读框内核糖体暂停的相对程度进行了定量。核糖体暂停程度与ATP合酶复合体中发现的蛋白质水平之间存在普遍但非绝对的相关性。我们得出结论，虽然核糖体暂停不是唯一因素，但它可能是影响菠菜叶绿体中大型ATP合酶基因簇表达的一个重要转录后机制。
