Schön A, Krupp G, Gough S, Berry-Lowe S, Kannangara C G, Söll D
Nature. 1986;322(6076):281-4. doi: 10.1038/322281a0.
A molecule of chlorophyll is synthesized from eight molecules of delta-aminolevulinate (DALA), the universal precursor of porphyrins. The light-regulated conversion of glutamate to delta-aminolevulinate in the stroma of greening plastids involves the reduction of glutamate to glutamate-1-semialdehyde and its subsequent transamination. The components performing this conversion have been isolated from barley and Chlamydomonas and separated into three fractions by serial affinity chromatography on Blue Sepharose and haem- or chlorophyllin-Sepharose. The complete reaction can be performed in vitro in a reconstituted assay by combining all three fractions. An RNA is the essential component of the chlorophyllin-Sepharose-bound fraction. By nucleotide sequence analysis, we have now identified this RNA as a chloroplast glutamate acceptor RNA. Glutamate attached by an aminoacyl bond to the 3'-terminal adenosine of this RNA is a substrate for the enzyme(s) which perform the subsequent reactions. This reaction represents a novel role for transfer RNA: participation in the metabolic conversion of its cognate amino acid into another metabolite of low relative molecular mass which subsequently is not used in peptide bond synthesis.
一个叶绿素分子由八个δ-氨基乙酰丙酸（DALA）分子合成，DALA是卟啉的通用前体。在叶绿体基质中，光调节的谷氨酸向δ-氨基乙酰丙酸的转化涉及谷氨酸还原为谷氨酸-1-半醛及其随后的转氨作用。进行这种转化的成分已从大麦和衣藻中分离出来，并通过在蓝色琼脂糖凝胶和血红素或叶绿素琼脂糖凝胶上的连续亲和层析分离成三个组分。通过将所有三个组分组合在一起，可以在体外重建试验中完成整个反应。一种RNA是与叶绿素琼脂糖凝胶结合的组分的必需成分。通过核苷酸序列分析，我们现在已将这种RNA鉴定为叶绿体谷氨酸受体RNA。通过氨酰基键连接到该RNA 3'-末端腺苷的谷氨酸是进行后续反应的酶的底物。该反应代表了转运RNA的一种新作用：参与其同源氨基酸向另一种相对分子质量较低的代谢物的代谢转化，该代谢物随后不用于肽键合成。
