scholarly journals The Hsp90 Cochaperones Cpr6, Cpr7, and Cns1 Interact with the Intact Ribosome

2014 ◽  
Vol 14 (1) ◽  
pp. 55-63 ◽  
Author(s):  
Victoria R. Tenge ◽  
Abbey D. Zuehlke ◽  
Neelima Shrestha ◽  
Jill L. Johnson
Keyword(s):  
Molecular Chaperone ◽  
Temperature Sensitive ◽  
Content Type ◽  
Amino Terminal ◽  
Growth Defects ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Carboxy Terminal ◽  
Tpr Domain

ABSTRACT The abundant molecular chaperone Hsp90 is essential for the folding and stabilization of hundreds of distinct client proteins. Hsp90 is assisted by multiple cochaperones that modulate Hsp90's ATPase activity and/or promote client interaction, but the in vivo functions of many of these cochaperones are largely unknown. We found that Cpr6, Cpr7, and Cns1 interact with the intact ribosome and that Saccharomyces cerevisiae lacking CPR7 or containing mutations in CNS1 exhibited sensitivity to the translation inhibitor hygromycin. Cpr6 contains a peptidyl-prolyl isomerase (PPIase) domain and a tetratricopeptide repeat (TPR) domain flanked by charged regions. Truncation or alteration of basic residues near the carboxy terminus of Cpr6 disrupted ribosome interaction. Cns1 contains an amino-terminal TPR domain and a poorly characterized carboxy-terminal domain. The isolated carboxy-terminal domain was able to interact with the ribosome. Although loss of CPR6 does not cause noticeable growth defects, overexpression of CPR6 results in enhanced growth defects in cells expressing the temperature-sensitive cns1-G90D mutation (the G-to-D change at position 90 encoded by cns1 ). Cpr6 mutants that exhibit reduced ribosome interaction failed to cause growth defects, indicating that ribosome interaction is required for in vivo functions of Cpr6. Together, these results represent a novel link between the Hsp90 molecular-chaperone machine and protein synthesis.

scholarly journals Residues near the Amino Terminus of Rns Are Essential for Positive Autoregulation and DNA Binding

2008 ◽  
Vol 190 (7) ◽  
pp. 2279-2285 ◽  
Author(s):  
Georgeta N. Basturea ◽  
Maria D. Bodero ◽  
Mario E. Moreno ◽  
George P. Munson
Keyword(s):  
Dna Binding ◽  
Amino Terminus ◽  
Amino Terminal ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Carboxy Terminal ◽  
Amino Terminal Domain ◽  
Regulated Promoters

ABSTRACT Most members of the AraC/XylS family contain a conserved carboxy-terminal DNA binding domain and a less conserved amino-terminal domain involved in binding small-molecule effectors and dimerization. However, there is no evidence that Rns, a regulator of enterotoxigenic Escherichia coli virulence genes, responds to an effector ligand, and in this study we found that the amino-terminal domain of Rns does not form homodimers in vivo. Exposure of Rns to the chemical cross-linker glutaraldehyde revealed that the full-length protein is also a monomer in vitro. Nevertheless, deletion analysis of Rns demonstrated that the first 60 amino acids of the protein are essential for the activation and repression of Rns-regulated promoters in vivo. Amino-terminal truncation of Rns abolished DNA binding in vitro, and two randomly generated mutations, I14T and N16D, that independently abolished Rns autoregulation were isolated. Further analysis of these mutations revealed that they have disparate effects at other Rns-regulated promoters and suggest that they may be involved in an interaction with the carboxy-terminal domain of Rns. Thus, evolution may have preserved the amino terminus of Rns because it is essential for the regulator's activity even though it apparently lacks the two functions, dimerization and ligand binding, usually associated with the amino-terminal domains of AraC/XylS family members.

Disruption of dynamic cell surface architecture of NIH3T3 fibroblasts by the N-terminal domains of moesin and ezrin: in vivo imaging with GFP fusion proteins

1999 ◽  
Vol 112 (1) ◽  
pp. 111-125 ◽  
Author(s):  
M.R. Amieva ◽  
P. Litman ◽  
L. Huang ◽  
E. Ichimaru ◽  
H. Furthmayr
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Fluorescent Protein ◽  
Cultured Cells ◽  
Full Length ◽  
Cell Behavior ◽  
Amino Terminal ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Carboxy Terminal

Lamellipodia, filopodia, microspikes and retraction fibers are characteristic features of a dynamic and continuously changing cell surface architecture and moesin, ezrin and radixin are thought to function in these microextensions as reversible links between plasma membrane proteins and actin microfilaments. Full-length and truncated domains of the three proteins were fused to green fluorescent protein (GFP), expressed in NIH3T3 cells, and distribution and behaviour of cells were analysed by using digitally enhanced differential interference contrast (DIC) and fluorescence video microscopy. The amino-terminal (N-)domains of all three proteins localize to the plasma membrane and fluorescence recordings parallel the dynamic changes in cell surface morphology observed by DIC microscopy of cultured cells. Expression of this domain, however, significantly affects cell surface architecture by the formation of abnormally long and fragile filopodia that poorly attach and retract abnormally. Even more striking are abundant irregular, branched and motionless membraneous structures that accumulate during retraction of lamellipodia. These are devoid of actin, endogenous moesin, ezrin and radixin, but contain the GFP-labeled domain. While a large proportion of endogenous proteins can be extracted with non-ionic detergents as in untransfected control cells, >90% of N-moesin and >60% of N-ezrin and N-radixin remain insoluble. The minimal size of the domain of moesin required for membrane localization and change in behavior includes residues 1–320. Deletions of amino acid residues from either end result in diffuse intracellular distribution, but also in normal cell behavior. Expression of GFP-fusions of full-length moesin or its carboxy-terminal domain has no effect on cell behavior during the observation period of 6–8 hours. The data suggest that, in the absence of the carboxy-terminal domain, N-moesin, -ezrin and -radixin interact tightly with the plasma membrane and interfere with normal functions of endogeneous proteins mainly during retraction.

scholarly journals The Nsp1p Carboxy-Terminal Domain Is Organized into Functionally Distinct Coiled-Coil Regions Required for Assembly of Nucleoporin Subcomplexes and Nucleocytoplasmic Transport

2001 ◽  
Vol 21 (23) ◽  
pp. 7944-7955 ◽  
Author(s):  
Susanne M. Bailer ◽  
Carolin Balduf ◽  
Ed Hurt
Keyword(s):  
Protein Import ◽  
Coiled Coil ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Temperature Sensitive ◽  
Nuclear Pores ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Carboxy Terminal

ABSTRACT Nucleoporin Nsp1p, which has four predicted coiled-coil regions (coils 1 to 4) in the essential carboxy-terminal domain, is unique in that it is part of two distinct nuclear pore complex (NPC) subcomplexes, Nsp1p-Nup57p-Nup49p-Nic96p and Nsp1p-Nup82p-Nup159p. As shown by in vitro reconstitution, coiled-coil region 2 (residues 673 to 738) is sufficient to form heterotrimeric core complexes and can bind either Nup57p or Nup82p. Accordingly, interaction of Nup82p with Nsp1p coil 2 is competed by excess Nup57p. Strikingly, coil 3 and 4 mutants are still assembled into the core Nsp1p-Nup57p-Nup49p complex but no longer associate with Nic96p. Consistently, the Nsp1p-Nup57p-Nup49p core complex dissociates from the nuclear pores in nsp1coil 3 and 4 mutant cells, and as a consequence, defects in nuclear protein import are observed. Finally, the nsp1-L640Stemperature-sensitive mutation, which maps in coil 1, leads to a strong nuclear mRNA export defect. Thus, distinct coiled-coil regions within Nsp1p-C have separate functions that are related to the assembly of different NPC subcomplexes, nucleocytoplasmic transport, and incorporation into the nuclear pores.

scholarly journals A Major Determinant for Membrane Protein Interaction Localizes to the Carboxy-Terminal Domain of the Mouse Coronavirus Nucleocapsid Protein

2005 ◽  
Vol 79 (21) ◽  
pp. 13285-13297 ◽  
Author(s):  
Kelley R. Hurst ◽  
Lili Kuo ◽  
Cheri A. Koetzner ◽  
Rong Ye ◽  
Bilan Hsue ◽  
...  
Keyword(s):  
Viral Envelope ◽  
M Protein ◽  
N Protein ◽  
Amino Terminal ◽  
Terminal Domain ◽  
Dominant Negative Mutation ◽  
Carboxy Terminal Domain ◽  
Domain 3 ◽  
Positive Strand Rna ◽  
Carboxy Terminal

ABSTRACT The two major constituents of coronavirus virions are the membrane (M) and nucleocapsid (N) proteins. The M protein is anchored in the viral envelope by three transmembrane segments flanked by a short amino-terminal ectodomain and a large carboxy-terminal endodomain. The M endodomain interacts with the viral nucleocapsid, which consists of the positive-strand RNA genome helically encapsidated by N protein monomers. In previous work with the coronavirus mouse hepatitis virus (MHV), a highly defective M protein mutant, MΔ2, was constructed. This mutant contained a 2-amino-acid carboxy-terminal truncation of the M protein. Analysis of second-site revertants of MΔ2 revealed mutations in the carboxy-terminal region of the N protein that compensated for the defect in the M protein. To seek further genetic evidence corroborating this interaction, we generated a comprehensive set of clustered charged-to-alanine mutants in the carboxy-terminal domain 3 of N protein. One of these mutants, CCA4, had a highly defective phenotype similar to that of MΔ2. Transfer of the CCA4 mutation into a partially diploid MHV genome showed that CCA4 was a loss-of-function mutation rather than a dominant-negative mutation. Analysis of multiple second-site revertants of CCA4 revealed mutations in both the M protein and the N protein that could compensate for the original lesion in N. These data more precisely define the region of the N protein that interacts with the M protein. Further, we found that fusion of domain 3 of the N protein to the carboxy terminus of a heterologous protein caused it to be incorporated into MHV virions.

Involvement of yeast carboxy-terminal domain kinase I (CTDK-I) in transcription elongation in vivo

Gene ◽  
2001 ◽  
Vol 267 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Ghil Jona ◽  
Birgitte Ø. Wittschieben ◽  
Jesper Q. Svejstrup ◽  
Opher Gileadi
Keyword(s):  
Transcription Elongation ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Carboxy Terminal

scholarly journals RNA Polymerase II Carboxy-Terminal Domain Phosphorylation Is Required for Cotranscriptional Pre-mRNA Splicing and 3′-End Formation

2004 ◽  
Vol 24 (20) ◽  
pp. 8963-8969 ◽  
Author(s):  
Gregory Bird ◽  
Diego A. R. Zorio ◽  
David L. Bentley
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Kinase Inhibitors ◽  
Mrna Splicing ◽  
Pol Ii ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Carboxy Terminal ◽  
Ctd Phosphorylation

ABSTRACT We investigated the role of RNA polymerase II (pol II) carboxy-terminal domain (CTD) phosphorylation in pre-mRNA processing coupled and uncoupled from transcription in Xenopus oocytes. Inhibition of CTD phosphorylation by the kinase inhibitors 5,6-dichloro-1β-d-ribofuranosyl-benzimidazole and H8 blocked transcription-coupled splicing and poly(A) site cleavage. These experiments suggest that pol II CTD phosphorylation is required for efficient pre-mRNA splicing and 3′-end formation in vivo. In contrast, processing of injected pre-mRNA was unaffected by either kinase inhibitors or α-amanitin-induced depletion of pol II. pol II therefore does not appear to participate directly in posttranscriptional processing, at least in frog oocytes. Together these experiments show that the influence of the phosphorylated CTD on pre-mRNA splicing and 3′-end processing is mediated by transcriptional coupling.

The carboxy-terminal domains of erbB-2 and epidermal growth factor receptor exert different regulatory effects on intrinsic receptor tyrosine kinase function and transforming activity

1990 ◽  
Vol 10 (6) ◽  
pp. 2749-2756
Author(s):  
P P Di Fiore ◽  
O Segatto ◽  
F Lonardo ◽  
F Fazioli ◽  
J H Pierce ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Kinase Activity ◽  
Growth Factor Receptor ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Epidermal Growth ◽  
Regulatory Effects ◽  
Carboxy Terminal

The erbB-2 gene product, gp185erbB-2, displays a potent transforming effect when overexpressed in NIH 3T3 cells. In addition, it possesses constitutively high levels of tyrosine kinase activity in the absence of exogenously added ligand. In this study, we demonstrate that its carboxy-terminal domain exerts an enhancing effect on erbB-2 kinase and transforming activities. A premature termination mutant of the erbB-2 protein, lacking the entire carboxy-terminal domain (erbB-2 delta 1050), showed a 40-fold reduction in transforming ability and a lowered in vivo kinase activity for intracellular substrates. When the carboxy-terminal domain of erbB-2 was substituted for its analogous region in the epidermal growth factor receptor (EGFR) (EGFR/erbB-2COOH chimera), it conferred erbB-2-like properties to the EGFR, including transforming ability in the absence of epidermal growth factor, elevated constitutive autokinase activity in vivo and in vitro, and constitutive ability to phosphorylate phospholipase C-gamma. Conversely, a chimeric erbB-2 molecule bearing an EGFR carboxy-terminal domain (erbB-2/EGFRCOOH chimera) showed reduced transforming and kinase activity with respect to the wild-type erbB-2 and was only slightly more efficient than the erbB-2 delta 1050 mutant. Thus, we conclude that the carboxy-terminal domains of erbB-2 and EGFR exert different regulatory effects on receptor kinase function and biological activity. The up regulation of gp185erbB-2 enzymatic activity exerted by its carboxy-terminal domain can explain, at least in part, its constitutive level of kinase activity.

scholarly journals Coenzyme F420-Dependent Glucose-6-Phosphate Dehydrogenase-Coupled Polyglutamylation of Coenzyme F420in Mycobacteria

2018 ◽  
Vol 200 (23) ◽  
Author(s):  
Endang Purwantini ◽  
Usha Loganathan ◽  
Biswarup Mukhopadhyay
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Genetic Analysis ◽  
The Other ◽  
Side Chain ◽  
Side Chains ◽  
Content Type ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Carboxy Terminal ◽  
Glucose 6 Phosphate Dehydrogenase

ABSTRACTCoenzyme F420plays a key role in the redox metabolisms of various archaea and bacteria, includingMycobacterium tuberculosis. InM. tuberculosis, F420-dependent reactions have been linked to several virulence factors. F420carries multiple glutamate residues in the side chain, forming F420-nspecies (n, number of glutamate residues), and the length of this side chain impacts cellular physiology.M. tuberculosisstrains with F420species carrying shorter side chains exhibit resistance to delamanid and pretomanid, two new tuberculosis (TB) drugs. Thus, the process of polyglutamylation of F420is of great interest. It has been known from genetic analysis that in mycobacteria an F420-0 γ-glutamyl ligase (FbiB) introduces up to seven glutamate residues into F420. However, purified FbiB ofM. tuberculosis(MtbFbiB) is either inefficient or incapable of incorporating more than two glutamates. We found that,in vitro,MtbFbiB synthesized side chains containing up to seven glutamate residues if F420was presented to the enzyme in a two-electron reduced state (F420H2). Our genetic analysis inMycobacterium bovisBCG andMycobacterium smegmatisand an analysis of literature data onM. tuberculosisrevealed that in these mycobacteria the polyglutamylation process requires the assistance of F420-dependent glucose-6-phosphate dehydrogenase (Fgd) which reduces F420to F420H2. We hypothesize that, starting with F420-0H2, the amino-terminal domain of FbiB builds F420-2H2, which is then transferred to the carboxy-terminal domain for further glutamylation; F420-2H2modifies the carboxy-terminal domain structurally to accommodate longer glutamyl chains. This system is analogous to folylpolyglutamate synthase, which introduces more than one glutamate residue into folate only after this vitamin is reduced to tetrahydrofolate.IMPORTANCECoenzyme F420-dependent reactions ofMycobacterium tuberculosis, which causes tuberculosis, potentially contributes to the virulence of this bacterium. The coenzyme carries a glutamic acid-derived tail, the length of which influences the metabolism ofM. tuberculosis. Mutations that eliminate the production of F420with longer tails makeM. tuberculosisresistant to two new tuberculosis drugs. This report describes that the synthesis of longer glutamyl tails of F420requires concerted actions of two enzymes, one of which reduces the coenzyme prior to the action of the other, which catalyzes polyglutamylation. This knowledge will help to develop more effective tuberculosis (TB) drugs. Remarkably, the introduction of multiple glutamate residues into the sidechain of folate (vitamin B9) requires similar concerted actions, where one enzyme reduces the vitamin to tetrahydrofolate and the other catalyzes polyglutamylation; folate is required for DNA and amino acid synthesis. Thus, the reported research has also revealed a key similarity between two important cellular systems.

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