INVITRO CAPPING IN TRYPANOSOMA-CRUZI IDENTIFIES AND SHOWS SPECIFICITY FOR THE SPLICED LEADER RNA AND U-RNAS

被引：8

作者：

ZWIERZYNSKI, TA ^{[1
]}

BUCK, GA ^{[1
]}

机构：

[1] VIRGINIA COMMONWEALTH UNIV,MED COLL VIRGINIA,DEPT MICROBIOL & IMMUNOL,RICHMOND,VA 23298

来源：

NUCLEIC ACIDS RESEARCH | 1990年 / 18卷 / 14期

关键词：

D O I：

10.1093/nar/18.14.4197

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Messenger RNA maturation in trypanosomes requires a trans-splicing event in which a capped 39 nucleotide leader sequence, the spliced leader (SL), from the 5' terminus of a small RNA (SL-RNA) is joined to the 5' termini of protein coding gene transcripts. We have developed nuclear extracts from Trypanosoma cruzi that label three small endogenous RNAs in the presence of [α-32P]GTP. Herein, we have characterized this labelling as 5' capping and shown that the capping activity exhibits an unusual ATP dependence. Moreover, partial sequence analysis identified the three cap-labelled RNAs as the T. cruzi SL-RNA, and two U-RNAs previously uncharacterized in T. cruzi, U2 and Ux. Finally, the capping reaction in the T. cruzi extracts showed apparent specificity for these RNAs-other endogenous or exogenous transcripts were not capped. The apparent specificity of this in vitro capping activity closely reflects the in vivo requirements; i.e., only the SL- and U-RNAs need to be capped since mature mRNAs are capped via frans-splicing. These observations are consistent with the hypothesis that one of the functions of trans-splicing is to supply 5' caps to mature trypanosome mRNAs. © 1990 Oxford University Press.

引用

页码：4197 / 4206

页数：10

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