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Identification of the sites of action of SrmB, a DEAD-box RNA helicase involved in Escherichia coli ribosome assembly
被引:27
作者:
Proux, Florence
[1
]
Dreyfus, Marc
[1
,2
]
Iost, Isabelle
[1
,3
]
机构:
[1] Ecole Normale Super, CNRS, Inst Biol, UMR 8197, F-75230 Paris 05, France
[2] Univ Paris Diderot, CNRS, Inst Biol Phys Chim, UPR9073, F-75005 Paris, France
[3] Univ Bordeaux, Lab ARNA, INSERM, U869, F-33076 Bordeaux, France
关键词:
FEEDBACK-REGULATION;
PROTEIN;
SUBUNIT;
GENES;
DBPA;
EXPRESSION;
MECHANISM;
CHAPERONE;
PRODUCTS;
OPERONS;
D O I:
10.1111/j.1365-2958.2011.07779.x
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:
DEAD-box RNA-dependent ATPases are ubiquitous enzymes that participate in nearly all processes involving RNA, but their detailed molecular functions remain generally unknown. SrmB, one of the five Escherichia coli DEAD-box proteins, participates in the assembly of the large ribosomal subunit notably by facilitating the incorporation of L13, one of the ribosomal proteins that bind 23S rRNA earliest. Previously, we showed that SrmB is tethered to nascent ribosome through interactions with L4, L24 and the region from domain I of 23S rRNA that binds them. To identify the sites of action of SrmB, we have characterized rRNA mutations that bypass SrmB requirement. Five of them affect the same position from two repeated heptanucleotides in domain II of 23S rRNA, whereas two others affect a complementary hexanucleotide in 5S rRNA. Thus the sites of action of SrmB differ from its tethering site. In the mature ribosome, one of the heptanucleotides participates in a highly compact structure that contacts L13, the '1024 G-ribo wrench'. In addition, we have observed that the assembly defect of Delta srmB cells worsens as rRNA synthesis increases. Based on these results, we propose two non-exclusive scenarios for the role of SrmB in ribosome assembly.
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页码:300 / 311
页数:12
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