Phosphorylation of the RNA-dependent protein kinase regulates its RNA-binding activity.

نویسندگان

  • N V Jammi
  • P A Beal
چکیده

The RNA-dependent protein kinase (PKR) is an interferon-induced, RNA-activated enzyme that phosphorylates the alpha-subunit of eukaryotic initiation factor 2 (eIF2alpha), inhibiting the function of the eIF2 complex and continued initiation of translation. When bound to an activating RNA and ATP, PKR undergoes autophosphorylation reactions at multiple serine and threonine residues. This autophosphorylation reaction stimulates the eIF2alpha kinase activity of PKR. The binding of certain viral RNAs inhibits the activation of PKR. Wild-type PKR is obtained as a highly phosphorylated protein when overexpressed in Escherichia coli. We report here that treatment of the isolated phosphoprotein with the catalytic subunit of protein phosphatase 1 dephosphorylates the enzyme. The in vitro autophosphorylation and eIF2alpha kinase activities of the dephosphorylated enzyme are stimulated by addition of RNA. Thus, inactivation by phosphatase treatment of autophosphorylated PKR obtained from overexpression in bacteria generates PKR in a form suitable for in vitro analysis of the RNA-induced activation mechanism. Furthermore, we used gel mobility shift assays, methidiumpropyl-EDTA.Fe footprinting and affinity chromatography to demonstrate differences in the RNA-binding properties of phospho- and dephosphoPKR. We found that dephosphorylation of PKR increases binding affinity of the enzyme for both kinase activating and inhibiting RNAs. These results are consistent with an activation mechanism that includes release of the activating RNA upon autophosphorylation of PKR prior to phosphorylation of eIF2alpha.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Phosphorylation of p68 RNA helicase regulates RNA binding by the C-terminal domain of the protein.

We previously reported ATPase, RNA unwinding, and RNA-binding activities of recombinant p68 RNA helicase that was expressed in Escherichia coli. Huang et al. The recombinant protein bound both single-stranded (ss) and double-stranded (ds) RNAs. To further characterize the substrate RNA binding by p68 RNA helicase, we expressed and purified the recombinant N-terminal and C-terminal domains of th...

متن کامل

Identification of RNA-binding sites in artemin based on docking energy landscapes and molecular dynamics simulation

There are questions concerning the functions of artemin, an abundant stress protein found in Artemiaduring embryo development. It has been reported that artemin binds RNA at high temperatures in vitro, suggesting an RNA protective role. In this study, we investigated the possibility of the presence of RNA-bindingsites and their structural properties in artemin, using docking energy ...

متن کامل

Nonstructural 5A Protein of Hepatitis C Virus Regulates Soluble Resistance-Related Calcium-Binding Protein Activity for Viral Propagation.

UNLABELLED Hepatitis C virus (HCV) is a major cause of chronic liver disease and is highly dependent on cellular proteins for virus propagation. To identify the cellular factors involved in HCV propagation, we recently performed protein microarray assays using the HCV nonstructural 5A (NS5A) protein as a probe. Of 90 cellular protein candidates, we selected the soluble resistance-related calciu...

متن کامل

O-2: Testosterone and Vitamin E administration Up-Regulates Hsp70 Protein Expression in Varicocele-induced Rats; Correlation with Leydig Cells Steroidogenesis and Germinal Cells RNA Damage

Background: Varicocele (VCL) impacts the testicular tissue partly by down-regulating the antioxidant status accomplished with reducing the intra-testicular endocrine potential. It has been reported that the HSP70 families play a critical role in spermiogenesis. Therefore, current study was aimed to evaluate the protective effect of exogenous testosterone and vitamin E administration on VCL-indu...

متن کامل

Phosphorylation of Staphylococcus aureus Protein-Tyrosine Kinase Affects the Function of Glucokinase and Biofilm Formation

Background: When Staphylococcus aureus is grown in the presence of high concentration of external glucose, this sugar is phosphorylated by glucokinase (glkA) to form glucose-6-phosphate. This product subsequently enters into anabolic phase, which favors biofilm formation. The presence of ROK (repressor protein, open reading frame, sugar kinase) motif, phosphate-1 and -2 sites, and tyrosine kina...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Nucleic acids research

دوره 29 14  شماره 

صفحات  -

تاریخ انتشار 2001