scholarly journals RNA helicases in RNA decay

2018 ◽  
Vol 46 (1) ◽  
pp. 163-172 ◽  
Author(s):  
Vanessa Khemici ◽  
Patrick Linder

RNA molecules have the tendency to fold into complex structures or to associate with complementary RNAs that exoribonucleases have difficulties processing or degrading. Therefore, degradosomes in bacteria and organelles as well as exosomes in eukaryotes have teamed-up with RNA helicases. Whereas bacterial degradosomes are associated with RNA helicases from the DEAD-box family, the exosomes and mitochondrial degradosome use the help of Ski2-like and Suv3 RNA helicases.

2017 ◽  
Vol 199 (13) ◽  
Author(s):  
Angel A. Aguirre ◽  
Alexandre M. Vicente ◽  
Steven W. Hardwick ◽  
Daniela M. Alvelos ◽  
Ricardo R. Mazzon ◽  
...  

ABSTRACT In diverse bacterial lineages, multienzyme assemblies have evolved that are central elements of RNA metabolism and RNA-mediated regulation. The aquatic Gram-negative bacterium Caulobacter crescentus, which has been a model system for studying the bacterial cell cycle, has an RNA degradosome assembly that is formed by the endoribonuclease RNase E and includes the DEAD-box RNA helicase RhlB. Immunoprecipitations of extracts from cells expressing an epitope-tagged RNase E reveal that RhlE, another member of the DEAD-box helicase family, associates with the degradosome at temperatures below those optimum for growth. Phenotype analyses of rhlE, rhlB, and rhlE rhlB mutant strains show that RhlE is important for cell fitness at low temperature and its role may not be substituted by RhlB. Transcriptional and translational fusions of rhlE to the lacZ reporter gene and immunoblot analysis of an epitope-tagged RhlE indicate that its expression is induced upon temperature decrease, mainly through posttranscriptional regulation. RNase E pulldown assays show that other proteins, including the transcription termination factor Rho, a second DEAD-box RNA helicase, and ribosomal protein S1, also associate with the degradosome at low temperature. The results suggest that the RNA degradosome assembly can be remodeled with environmental change to alter its repertoire of helicases and other accessory proteins. IMPORTANCE DEAD-box RNA helicases are often present in the RNA degradosome complex, helping unwind secondary structures to facilitate degradation. Caulobacter crescentus is an interesting organism to investigate degradosome remodeling with change in temperature, because it thrives in freshwater bodies and withstands low temperature. In this study, we show that at low temperature, the cold-induced DEAD-box RNA helicase RhlE is recruited to the RNA degradosome, along with other helicases and the Rho protein. RhlE is essential for bacterial fitness at low temperature, and its function may not be complemented by RhlB, although RhlE is able to complement for rhlB loss. These results suggest that RhlE has a specific role in the degradosome at low temperature, potentially improving adaptation to this condition.


1995 ◽  
Vol 308 (3) ◽  
pp. 839-846 ◽  
Author(s):  
J Sowden ◽  
W Putt ◽  
K Morrison ◽  
R Beddington ◽  
Y Edwards

DEAD box proteins share several highly conserved motifs including the characteristic Asp-Glu-Ala-Asp (D-E-A-D in the amino acid single-letter code) motif and have established or putative ATP-dependent RNA helicase activity. These proteins are implicated in a range of cellular processes that involve regulation of RNA function, including translation initiation, RNA splicing and ribosome assembly. Here we describe the isolation and characterization of an embryonic RNA helicase gene, ERH, which maps to mouse chromosome 1 and encodes a new member of the DEAD box family of proteins. The predicted ERH protein shows high sequence similarity to the testes-specific mouse PL10 and to the maternally acting Xenopus An3 helicase proteins. The ERH expression profile is similar, to that of An3, which localizes to the animal hemisphere of oocytes and is abundantly expressed in the embryo. ERH is expressed in oocytes and is a ubiquitous mRNA in the 9 days-post-conception embryo, and at later stages of development shows a more restricted pattern of expression in brain and kidney. The similarities in sequence and in expression profile suggest that ERH is the murine equivalent of the Xenopus An3 gene, and we propose that ERH plays a role in translational activation of mRNA in the oocyte and early embryo.


2018 ◽  
Vol 9 ◽  
Author(s):  
José Antonio González-Gutiérrez ◽  
Diana Fabiola Díaz-Jiménez ◽  
Itzel Vargas-Pérez ◽  
Gabriel Guillén-Solís ◽  
Jörg Stülke ◽  
...  

2001 ◽  
Vol 15 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Qinglin Ou ◽  
Jean-François Mouillet ◽  
Xiaomei Yan ◽  
Christoph Dorn ◽  
Peter A. Crawford ◽  
...  

Abstract The nuclear receptor steroidogenic factor-1 (SF-1) is essential for development of the gonads, adrenal gland, and the ventromedial hypothalamic nucleus. It also regulates the expression of pivotal steroidogenic enzymes and other important proteins in the reproductive system. We sought to elucidate the mechanisms that govern the transcriptional activity of SF-1. We demonstrate here that a previously uncharacterized domain, located C-terminal to the DNA binding domain of SF-1, exhibits transcriptional repression function. Point mutations in this domain markedly potentiate the transcriptional activity of native SF-1. Using an SF-1 region that spans this proximal repression domain as bait in a yeast two-hybrid system, we cloned an SF-1 interacting protein that is homologous to human DP103, a member of the DEAD box family of putative RNA helicases. DP103 directly interacts with the proximal repression domain of SF-1, and mutations in this domain abrogate its interaction with DP103. DP103 is expressed predominantly in the testis and is also expressed at a lower level in other steroidogenic and nonsteroidogenic tissues. Functionally, DP103 exhibits a native transcriptional repression function that localizes to the C-terminal region of the protein and represses the activity of wild-type, but not mutant, SF-1. Together, the physical and functional interaction of DP103 with a previously unrecognized repression domain within SF-1 represents a novel mechanism for regulation of SF-1 activity.


2017 ◽  
Author(s):  
Linlin Zhang ◽  
Beibei Li ◽  
Yuxi Yang ◽  
Ian C. Scott ◽  
Xin Lou

AbstractRNA helicases from the DEAD-box family are found in almost all organisms and have important roles in RNA metabolism including RNA synthesis, processing and degradation. The function and mechanism of action of most of these helicases in animal development and human disease are largely unexplored. In a zebrafish mutagenesis screen to identify genes essential for heart development we identified a zebrafish mutant, which disrupts the gene encoding the RNA helicase DEAD-box 39a (ddx39a).Homozygous ddx39a mutant embryos exhibit profound cardiac and trunk muscle dystrophy, along with lens abnormalities caused by abrupt terminal differentiation of cardiomyocyte, myoblast and lens fiber cells. Further investigation indicated that loss of ddx39a hindered mRNA splicing of members of the kmt2 gene family, leading to mis-regulation of structural gene expression in cardiomyocyte, myoblast and lens fiber cells. Taken together, these results show that Ddx39a plays an essential role in establishment of proper epigenetic status during cell differentiation.


Author(s):  
Zhaofeng Gao ◽  
Andrea A Putnam ◽  
Heath A Bowers ◽  
Ulf-Peter Guenther ◽  
Xuan Ye ◽  
...  

1997 ◽  
Vol 17 (4) ◽  
pp. 2257-2265 ◽  
Author(s):  
Z J Lorković ◽  
R G Herrmann ◽  
R Oelmüller

The putative RNA helicases of the DEAD-box protein family are involved in pre-mRNA splicing, rRNA maturation, ribosome assembly, and translation. Members of this protein family have been identified in organisms from Escherichia coli to humans, but except for the translation initiation factor 4A, there have been no reports on the characterization of other DEAD-box proteins from plants. Here we report on a novel member of the DEAD-box protein family, the plant RNA helicase 75 (PRH75). PRH75 is localized in the nucleus and contains two domains for RNA binding. One is located at the C terminus and is similar to RGG RNA-binding domains of nucleus-localized RNA-binding proteins. The other one is located between amino acids 308 and 622, a region containing the conserved motif VI characteristic of DEAD-box proteins and known as the RNA-binding site of eIF-4A. The N-terminal 81 amino acids are sufficient for nuclear targeting of the protein. Northern and Western blot analyses show that PRH75 is mainly expressed in young and rapidly developing tissues. The purified recombinant PRH75 has a weak ATPase activity which is barely stimulated by RNA ligands. The fractionation of spinach whole-cell extracts by glycerol gradient centrifugation and gel filtration on a Superdex 200 column shows that the protein exists in a complex of about 500 kDa. Possible biological functions of PRH75 as well as structure-function relationships in the context of its modular primary structure are discussed.


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