eIF2B, a mediator of general and gene-specific translational control

2005 ◽  
Vol 33 (6) ◽  
pp. 1487-1492 ◽  
Author(s):  
G.D. Pavitt
Keyword(s):  
Translational Control ◽  
Biochemical Analysis ◽  
Molecular Genetic ◽  
Structure And Function ◽  
Initiation Factor ◽  
Protein Synthesis Initiation ◽  
Vanishing White Matter Disease ◽  
And Function ◽  
Vanishing White Matter ◽  
Childhood Ataxia

eIF2B (eukaryotic initiation factor 2B) is a multisubunit protein that is required for protein synthesis initiation and its regulation in all eukaryotic cells. Mutations in eIF2B have also recently been found to cause a fatal human disease called CACH (childhood ataxia with central nervous system hypomyelination) or VWM (vanishing white matter disease). This review provides a general background to translation initiation and mechanisms known to control eIF2B function, before describing molecular genetic and biochemical analysis of eIF2B structure and function, integrating work from studies of the yeast and mammalian eIF2B proteins.

scholarly journals Vanishing White Matter Disease Expression of Truncated EIF2B5 Activates Induced Stress Response

2020 ◽  
Author(s):  
Matthew D. Keefe ◽  
Haille E. Soderholm ◽  
Hung-Yu Shih ◽  
Tamara J. Stevenson ◽  
Kathryn A. Glaittli ◽  
...  
Keyword(s):  
White Matter ◽  
Motor Behavior ◽  
Somatic Growth ◽  
Initiation Factor ◽  
White Matter Disease ◽  
The Central Nervous System ◽  
Oligodendrocyte Precursor ◽  
Vanishing White Matter Disease ◽  
Development And Validation ◽  
Vanishing White Matter

AbstractVanishing White Matter disease (VWM) is a severe leukodystrophy of the central nervous system caused by mutations in subunits of the eukaryotic initiation factor 2B complex (eIF2B). Current models only partially recapitulate key disease features, and pathophysiology is poorly understood. Through development and validation of zebrafish (Danio rerio) models of VWM, we demonstrate that zebrafish eif2b mutants phenocopy VWM, including impaired somatic growth, early lethality, impaired myelination, loss of oligodendrocyte precursor cells, increased apoptosis in the CNS, and impaired motor swimming behavior. Expression of human EIF2B2 in the zebrafish eif2b2 mutant rescues lethality and CNS apoptosis, demonstrating conservation of function between zebrafish and human. In the mutants, intron 12 retention leads to expression of a truncated eif2b5 transcript. Expression of the truncated eif2b5 in wild-type larva impairs motor behavior and activates the ISR, suggesting that a feed-forward mechanism in VWM is a significant component of disease pathophysiology.

scholarly journals The encapsulin from Thermatoga maritima is a flavoprotein with a symmetry matched ferritin-like cargo protein

2021 ◽  
Author(s):  
Benjamin J LaFrance ◽  
Caleb Cassidy-Amstutz ◽  
Robert J Nichols ◽  
Luke M Oltrogge ◽  
Eva Nogales ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Biochemical Analysis ◽  
Active Role ◽  
Structure And Function ◽  
Redox Active ◽  
Cargo Protein ◽  
Cargo Proteins ◽  
And Function ◽  
Flavin Binding ◽  
Unique Chemical

Bacterial nanocompartments, also known as encapsulins, are an emerging class of protein-based "organelles" found in bacteria and archaea. Encapsulins are virus-like icosahedral particles comprising a ~25-50 nm shell surrounding a specific cargo enzyme. Compartmentalization is thought to create a unique chemical environment to facilitate catalysis and isolate toxic intermediates. Many questions regarding nanocompartment structure-function remain unanswered, including how shell symmetry dictates cargo loading and to what extent the shell facilitates enzymatic activity. Here, we explore these questions using the model T. maritima nanocompartment known to encapsulate a redox-active ferritin-like protein. Biochemical analysis revealed the encapsulin shell to possess a flavin binding site located at the interface between capsomere subunits, suggesting the shell may play a direct and active role in the function of the encapsulated cargo. Furthermore, we used cryoEM to show that cargo proteins use a form of symmetry-matching to facilitate encapsulation and define stoichiometry. In the case of the T. maritima encapsulin, the decameric cargo protein with 5-fold symmetry preferentially binds to the pentameric-axis of the icosahedral shell. Taken together, these observations suggest the shell is not simply a passive barrier-it also plays a significant role in the structure and function of the cargo enzyme.

scholarly journals A Retrospective on eIF2A—and Not the Alpha Subunit of eIF2

2020 ◽  
Vol 21 (6) ◽  
pp. 2054
Author(s):  
Anton A. Komar ◽  
William C. Merrick
Keyword(s):  
Translational Control ◽  
Ribosomal Subunit ◽  
Initiation Factor ◽  
Single Chain ◽  
Initiation Factors ◽  
Eif2α Phosphorylation ◽  
Specific Mrnas ◽  
Internal Initiation ◽  
And Function ◽  
Polypeptide Chains

Initiation of protein synthesis in eukaryotes is a complex process requiring more than 12 different initiation factors, comprising over 30 polypeptide chains. The functions of many of these factors have been established in great detail; however, the precise role of some of them and their mechanism of action is still not well understood. Eukaryotic initiation factor 2A (eIF2A) is a single chain 65 kDa protein that was initially believed to serve as the functional homologue of prokaryotic IF2, since eIF2A and IF2 catalyze biochemically similar reactions, i.e., they stimulate initiator Met-tRNAi binding to the small ribosomal subunit. However, subsequent identification of a heterotrimeric 126 kDa factor, eIF2 (α,β,γ) showed that this factor, and not eIF2A, was primarily responsible for the binding of Met-tRNAi to 40S subunit in eukaryotes. It was found however, that eIF2A can promote recruitment of Met-tRNAi to 40S/mRNA complexes under conditions of inhibition of eIF2 activity (eIF2α-phosphorylation), or its absence. eIF2A does not function in major steps in the initiation process, but is suggested to act at some minor/alternative initiation events such as re-initiation, internal initiation, or non-AUG initiation, important for translational control of specific mRNAs. This review summarizes our current understanding of the eIF2A structure and function.

scholarly journals Vanishing White Matter Disease in a Spanish Population

2014 ◽  
Vol 6 ◽  
pp. JCNSD.S13540 ◽  
Author(s):  
Eulàlia Turón-Viñas ◽  
Mercè Pineda ◽  
Victòria Cusí ◽  
Eduardo López-Laso ◽  
Rebeca Losada Del Pozo ◽  
...  
Keyword(s):  
White Matter ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Eukaryotic Translation ◽  
Genes Encoding ◽  
Eukaryotic Translation Initiation ◽  
Severe Ataxia ◽  
Vanishing White Matter Disease ◽  
Chronic Course ◽  
Vanishing White Matter

Vanishing white matter (VWM) leukoencephalopathy is one of the most prevalent hereditary white matter diseases. It has been associated with mutations in genes encoding eukaryotic translation initiation factor ( eIF2B). We have compiled a list of all the patients diagnosed with VWM in Spain; we found 21 children. The first clinical manifestation in all of them was spasticity, with severe ataxia in six patients, hemiparesis in one child, and dystonic movements in another. They suffered from progressive cognitive deterioration and nine of them had epilepsy too. In four children, we observed optic atrophy and three also had progressive macrocephaly, which is not common in VWM disease. The first two cases were diagnosed before the 1980s. Therefore, they were diagnosed by necropsy studies. The last 16 patients were diagnosed according to genetics: we found mutations in the genes eIF2B5 (13 cases), eIF2B3 (2 cases), and eIF2B4 (1 case). In our report, the second mutation in frequency was c.318A>T; patients with this mutation all followed a slow chronic course, both in homozygous and heterozygous states. Previously, there were no other reports to confirm this fact. We also found some mutations not described in previous reports: c.1090C>T in eIF2B4, c.314A>G in eIF2B5, and c.877C>T in eIF2B5.

scholarly journals Vanishing white matter disease expression of truncated EIF2B5 activates induced stress response

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Matthew D Keefe ◽  
Haille E Soderholm ◽  
Hung-Yu Shih ◽  
Tamara J Stevenson ◽  
Kathryn A Glaittli ◽  
...  
Keyword(s):  
White Matter ◽  
Motor Behavior ◽  
Somatic Growth ◽  
Initiation Factor ◽  
White Matter Disease ◽  
The Central Nervous System ◽  
Oligodendrocyte Precursor ◽  
Vanishing White Matter Disease ◽  
Development And Validation ◽  
Vanishing White Matter

Vanishing white matter disease (VWM) is a severe leukodystrophy of the central nervous system caused by mutations in subunits of the eukaryotic initiation factor 2B complex (eIF2B). Current models only partially recapitulate key disease features, and pathophysiology is poorly understood. Through development and validation of zebrafish (Danio rerio) models of VWM, we demonstrate that zebrafish eif2b mutants phenocopy VWM, including impaired somatic growth, early lethality, effects on myelination, loss of oligodendrocyte precursor cells, increased apoptosis in the CNS, and impaired motor swimming behavior. Expression of human EIF2B2 in the zebrafish eif2b2 mutant rescues lethality and CNS apoptosis, demonstrating conservation of function between zebrafish and human. In the mutants, intron 12 retention leads to expression of a truncated eif2b5 transcript. Expression of the truncated eif2b5 in wild-type larva impairs motor behavior and activates the ISR, suggesting that a feed-forward mechanism in VWM is a significant component of disease pathophysiology.

scholarly journals The encapsulin from Thermotoga maritima is a flavoprotein with a symmetry matched ferritin-like cargo protein

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Benjamin J. LaFrance ◽  
Caleb Cassidy-Amstutz ◽  
Robert J. Nichols ◽  
Luke M. Oltrogge ◽  
Eva Nogales ◽  
...  
Keyword(s):  
Biochemical Analysis ◽  
Thermotoga Maritima ◽  
Active Role ◽  
Structure And Function ◽  
Redox Active ◽  
Cargo Protein ◽  
Cargo Proteins ◽  
And Function ◽  
Flavin Binding ◽  
Unique Chemical

AbstractBacterial nanocompartments, also known as encapsulins, are an emerging class of protein-based ‘organelles’ found in bacteria and archaea. Encapsulins are virus-like icosahedral particles comprising a ~ 25–50 nm shell surrounding a specific cargo enzyme. Compartmentalization is thought to create a unique chemical environment to facilitate catalysis and isolate toxic intermediates. Many questions regarding nanocompartment structure–function remain unanswered, including how shell symmetry dictates cargo loading and to what extent the shell facilitates enzymatic activity. Here, we explore these questions using the model Thermotoga maritima nanocompartment known to encapsulate a redox-active ferritin-like protein. Biochemical analysis revealed the encapsulin shell to possess a flavin binding site located at the interface between capsomere subunits, suggesting the shell may play a direct and active role in the function of the encapsulated cargo. Furthermore, we used cryo-EM to show that cargo proteins use a form of symmetry-matching to facilitate encapsulation and define stoichiometry. In the case of the Thermotoga maritima encapsulin, the decameric cargo protein with fivefold symmetry preferentially binds to the pentameric-axis of the icosahedral shell. Taken together, these observations suggest the shell is not simply a passive barrier—it also plays a significant role in the structure and function of the cargo enzyme.

Cognitive Neuroscience Approaches to Personality Disorders

2018 ◽  
Author(s):  
Andrew Poppe ◽  
Angus W. MacDonald III
Keyword(s):  
Personality Disorders ◽  
Cognitive Neuroscience ◽  
Brain Structure ◽  
Molecular Genetic ◽  
Structure And Function ◽  
Neural Processes ◽  
Brain Structure And Function ◽  
And Function ◽  
And Behavior

This chapter describes a cognitive neuroscience approach to understanding the psychological and neural processes that underlie personality and behavior. It explicates the utility of the cognitive neuroscience approach and the fundamental principles of the methods and how to interpret the findings. The chapter reviews the different neuroimaging tools and approaches that can be used to investigate brain structure and function. In doing so, it provides detailed information about what each method measures and how issues to consider when evaluating these measurements and their functional significance. The chapter provides the reader an appreciation of how understanding brain structure and function in vivo can serve as a bridge between molecular/genetic and symptom-based data to enrich the pathophysiology of personality disorders.

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