MATURATION OF A HYPERMODIFIED NUCLEOSIDE IN TRANSFER-RNA
MATURATION OF A HYPERMODIFIED NUCLEOSIDE IN TRANSFER-RNA
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DOI：
10.1093/nar/2.5.691
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发表时间：
1975-01-01
影响因子：
14.9
通讯作者：
SOLL, D
中科院分区：
文献类型：
--
作者：
AGRIS, PF;ARMSTRONG, DJ;SOLL, D
大肠杆菌C6 rel-met-cys-在完全补充的培养基和缺乏半胱氨酸或甲硫氨酸的培养基中培养。从三种培养物中分离的tRNA分别含有修饰核苷的正常补体;巯基化核苷的缺乏和甲基化核苷的缺乏。缺硫的tPNA和缺甲基的tRNA都含有大量的N6-（Δ 2-异戊烯基）腺苷和少量的2-甲硫基衍生物。甲基缺陷型tRNA含有大量细胞分裂素活性的不同修饰的核苷，被认为是N6-（δ 2-异戊烯基）腺苷的硫衍生物。这种化合物的结构尚不清楚。当甲基缺失的tRNA和tRNATyrsu3$A25的前体在体外被酶促甲基化时，甲基被掺入异戊烯基腺苷的衍生物中。这些结果表明，异戊烯基腺苷的2-甲硫基衍生物的生物合成可能以顺序方式发生，即，异戊烯基腺苷的硫醇化，然后甲基化。
E.coliC6 rel−met−cys−was cultured in a fully supplemented medium and in media lacking cysteine or methionine. tRNA isolated from the three cultures contained, respectively, a normal complement of modified nucleosides; a deficiency in thiolated nucleosides and a deficiency in methylated nucleosides. Both sulfur-deficient tPNA and methyl-deficient tRNA contained large amounts of N6-(Δ2-isopentenyl)adenosine and small amounts of the 2-methylthio derivative. Methyl-deficient tRNA contained, in addition a large amount of a cytokinin active, differently modified nucleoside that is believed to be a sulfur derivative of N6-(δ2-isopentenyl)adenosine. The structure of this compound is unknown. When methyl-deficient tRNA and the precursor to tRNATyrsu3$A25 were enzymatically methylatedinvitro, methyl groups were incorporated into derivatives of isopentenyladenosine. These results indicate that the biosynthesis of the 2-methylthio derivative of isopentenyladenosine may occur in a sequential manner, i.e., thiolation of isopentenyladenosine followed by methylation.