Stem-loop Binding Protein and Metal Carcinogenesis

ABSTRACT The limited coding capacity of picornavirus genomic RNAs necessitates utilization of host cell factors in the completion of an infectious cycle. One host protein that plays a role in both translation initiation and viral RNA synthesis is poly(rC) binding protein 2 (PCBP2). For picornavirus RNAs containing type I internal ribosome entry site (IRES) elements, PCBP2 binds the major stem-loop structure (stem-loop IV) in the IRES and is essential for translation initiation. Additionally, the binding of PCBP2 to the 5′-terminal stem-loop structure (stem-loop I or cloverleaf) in concert with viral protein 3CD is required for initiation of RNA synthesis directed by poliovirus replication complexes. PCBP1, a highly homologous isoform of PCBP2, binds to poliovirus stem-loop I with an affinity similar to that of PCBP2; however, PCBP1 has reduced affinity for stem-loop IV. Using a dicistronic poliovirus RNA, we were able to functionally uncouple translation and RNA replication in PCBP-depleted extracts. Our results demonstrate that PCBP1 rescues RNA replication but is not able to rescue translation initiation. We have also generated mutated versions of PCBP2 containing site-directed lesions in each of the three RNA-binding domains. Specific defects in RNA binding to either stem-loop I and/or stem-loop IV suggest that these domains may have differential functions in translation and RNA replication. These predictions were confirmed in functional assays that allow separation of RNA replication activities from translation. Our data have implications for differential picornavirus template utilization during viral translation and RNA replication and suggest that specific PCBP2 domains may have distinct roles in these activities.

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Polypyrimidine tract-binding protein interacts with the 3′ stem-loop region of Japanese encephalitis virus negative-strand RNA

Virus Research ◽

10.1016/j.virusres.2005.07.013 ◽

2006 ◽

Vol 115 (2) ◽

pp. 131-140 ◽

Cited By ~ 20

Author(s):

Seong Man Kim ◽

Yong Seok Jeong

Keyword(s):

Japanese Encephalitis Virus ◽

Japanese Encephalitis ◽

Binding Protein ◽

Encephalitis Virus ◽

Polypyrimidine Tract ◽

Stem Loop ◽

Negative Strand ◽

Polypyrimidine Tract Binding ◽

Polypyrimidine Tract Binding Protein ◽

Loop Region

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Regulation of interaction of the iron-responsive element binding protein with iron-responsive RNA elements

Molecular and Cellular Biology ◽

10.1128/mcb.9.11.5055-5061.1989 ◽

1989 ◽

Vol 9 (11) ◽

pp. 5055-5061

Author(s):

D J Haile ◽

M W Hentze ◽

T A Rouault ◽

J B Harford ◽

R D Klausner

Keyword(s):

Binding Protein ◽

Reduced Form ◽

Scatchard Analysis ◽

Stem Loop ◽

Lower Affinity ◽

Translational Repressor ◽

High Affinity ◽

Iron Responsive Element ◽

Responsive Element

The 5' untranslated region of the ferritin heavy-chain mRNA contains a stem-loop structure called an iron-responsive element (IRE), that is solely responsible for the iron-mediated control of ferritin translation. A 90-kilodalton protein, called the IRE binding protein (IRE-BP), binds to the IRE and acts as a translational repressor. IREs also explain the iron-dependent control of the degradation of the mRNA encoding the transferrin receptor. Scatchard analysis reveals that the IRE-BP exists in two states, each of which is able to specifically interact with the IRE. The higher-affinity state has a Kd of 10 to 30 pM, and the lower affinity state has a Kd of 2 to 5 nM. The reversible oxidation or reduction of a sulfhydryl is critical to this switching, and the reduced form is of the higher affinity while the oxidized form is of lower affinity. The in vivo rate of ferritin synthesis is correlated with the abundance of the high-affinity form of the IRE-BP. In lysates of cells treated with iron chelators, which decrease ferritin biosynthesis, a four- to fivefold increase in the binding activity is seen and this increase is entirely caused by an increase in high-affinity binding sites. In desferrioxamine-treated cells, the high-affinity form makes up about 50% of the total IRE-BP, whereas in hemin-treated cells, the high-affinity form makes up less than 1%. The total amount of IRE-BP in the cytosol of cells is the same regardless of the prior iron treatment of the cell. Furthermore, a mutated IRE is not able to interact with the IRE-BP in a high-affinity form but only at a single lower affinity Kd of 0.7 nM. Its interaction with the IRE-BP is insensitive to the sulfhydryl status of the protein.

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The stem-loop binding protein CDL-1 is required for chromosome condensation, progression of cell death and morphogenesis inCaenorhabditis elegans

Development ◽

10.1242/dev.129.1.187 ◽

2002 ◽

Vol 129 (1) ◽

pp. 187-196 ◽

Cited By ~ 1

Author(s):

Yuki Kodama ◽

Joel H. Rothman ◽

Asako Sugimoto ◽

Masayuki Yamamoto

Keyword(s):

Cell Death ◽

Structural Changes ◽

Binding Protein ◽

Core Histone ◽

Loss Of Function ◽

Histone Proteins ◽

Stem Loop ◽

C Elegans ◽

Morphological Defects ◽

In The Wild

Histones play important roles not only in the structural changes of chromatin but also in regulating gene expression. Expression of histones is partly regulated post-transcriptionally by the stem-loop binding protein (SLBP)/hairpin binding protein (HBP). We report the developmental function of CDL-1, the C. elegans homologue of SLBP/HBP. In the C. elegans cdl-1 mutants, cell corpses resulting from programmed cell death appear later and persist much longer than those in the wild type. They also exhibit distinct morphological defects in body elongation and movement of the pharyngeal cells toward the buccal opening. The CDL-1 protein binds to the stem-loop structures in the 3′-UTR of C. elegans core histone mRNAs, and the mutant forms of this protein show reduced binding activities. A decrease in the amount of core histone proteins phenocopied the cdl-1 mutant embryos, suggesting that CDL-1 contributes to the proper expression of core histone proteins. We propose that loss-of-function of cdl-1 causes aberrant chromatin structure, which affects the cell cycle and cell death, as well as transcription of genes essential for morphogenesis.

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