Structure and function of glutamyl-tRNA reductase involved in 5-aminolaevulinic acid formation

2002 ◽  
Vol 30 (4) ◽  
pp. 579-584 ◽  
Author(s):  
J. Moser ◽  
W.-D. Schubert ◽  
D. W. Heinz ◽  
D. Jahn
Keyword(s):  
Crystal Structure ◽  
Structure And Function ◽  
Acid Formation ◽  
Aminolaevulinic Acid ◽  
Metabolic Channelling ◽  
Initial Substrate ◽  
And Function ◽  
Reactive Aldehyde

In most bacteria, in archaea and in plants, the general precursor of all tetrapyrroles, 5-amino-laevulinic acid, is formed by two enzymes. The initial substrate, glutamyl-tRNA, is reduced by NADPH-dependent glutamyl-tRNA reductase to form glutamate 1-semialdehyde. The aldehyde is subsequently transaminated by glutamate-1-semi-aldehyde 2,1-aminomutase to yield 5-amino-laevulinic acid. The enzymic mechanism and the solved crystal structure of Methanopyrrus kandleri glutamyl-tRNA reductase are described. A pathway for metabolic channelling of the reactive aldehyde between glutamyl-tRNA reductase and the aminomutase is proposed.

scholarly journals The Contribution of Ribosomal Protein S1 to the Structure and Function of Qβ Replicase

Acta Naturae ◽  
2017 ◽  
Vol 9 (4) ◽  
pp. 26-30
Author(s):  
Z. Sh. Kutlubaeva ◽  
Е. V. Chetverina ◽  
A. B. Chetverin
Keyword(s):  
Crystal Structure ◽  
Ribosomal Protein ◽  
Rna Binding ◽  
Structure And Function ◽  
Ribosomal Protein S1 ◽  
Bacterial Ribosome ◽  
New Findings ◽  
Replicase Complex ◽  
And Function ◽  
Fixed Structure

The high resolution crystal structure of bacterial ribosome was determined more than 10 years ago; however, it contains no information on the structure of the largest ribosomal protein, S1. This unusual protein comprises six flexibly linked domains; therefore, it lacks a fixed structure and this prevents the formation of crystals. Besides being a component of the ribosome, protein S1 also serves as one of the four subunits of Q replicase, the RNA-directed RNA polymerase of bacteriophage Q. In each case, the role of this RNA-binding protein has been thought to consist in holding the template close to the active site of the enzyme. In recent years, a breakthrough was made in studies of protein S1 within Q replicase. This includes the discovery of its paradoxical ability to displace RNA from the replicase complex and determining the crystal structure of its fragment capable of performing this function. The new findings call for a re-examination of the contribution of protein S1 to the structure and function of the ribosome.

scholarly journals Structure of nonstructural protein 1 from SARS-CoV-2.

2020 ◽  
Author(s):  
Lauren K. Clark ◽  
Todd J. Green ◽  
Chad M. Petit
Keyword(s):  
Crystal Structure ◽  
Life Cycle ◽  
High Resolution ◽  
Nonstructural Protein ◽  
Critical Role ◽  
Viral Life Cycle ◽  
Structure And Function ◽  
Future Studies ◽  
Nonstructural Protein 1 ◽  
And Function

The periodic emergence of novel coronaviruses (CoVs) represents an ongoing public health concern with significant health and financial burden worldwide. The most recent occurrence originated in the city of Wuhan, China where a novel coronavirus (SARS-CoV-2) emerged causing severe respiratory illness and pneumonia. The continual emergence of novel coronaviruses underscores the importance of developing effective vaccines as well as novel therapeutic options that target either viral functions or host factors recruited to support coronavirus replication. The CoV nonstructural protein 1 (nsp1) has been shown to promote cellular mRNA degradation, block host cell translation, and inhibit the innate immune response to virus infection. Interestingly, deletion of the nsp1-coding region in infectious clones prevented the virus from productively infecting cultured cells. Because of nsp1’s importance in the CoV life cycle, it has been highlighted as a viable target for both antiviral therapy and vaccine development. However, the fundamental molecular and structural mechanisms that underlie nsp1 function remain poorly understood, despite its critical role in the viral life cycle. Here we report the high-resolution crystal structure of the amino, globular portion of SARS-CoV-2 nsp1 (residues 10 – 127) at 1.77 Å resolution. A comparison of our structure with the SARS-CoV-1 nsp1 structure reveals how mutations alter the conformation of flexible loops, inducing the formation of novel secondary structural elements and new surface features. Paired with the recently published structure of the carboxyl end of nsp1 (residues 148 – 180), our results provide the groundwork for future studies focusing on SARS-CoV-2 nsp1 structure and function during the viral life cycle. IMPORTANCE The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the causative agent for the COVID-19 pandemic. One protein known to play a critical role in the coronavirus life cycle is nonstructural protein1 (nsp1). As such, it has been highlighted in numerous studies as a target for both the development of antivirals and for the design of live-attenuated vaccines. Here we report the high-resolution crystal structure of nsp1 derived from SARS-CoV-2 at 1.77 Å resolution. This structure will facilitate future studies focusing on understanding the relationship between structure and function for nsp1. In turn, understanding these structure-function relationships will allow nsp1 to be fully exploited as a target for both antiviral development and vaccine design.

scholarly journals Structure and function of the yeast listerin (Ltn1) conserved N-terminal domain in binding to stalled 60S ribosomal subunits

2016 ◽  
Vol 113 (29) ◽  
pp. E4151-E4160 ◽  
Author(s):  
Selom K. Doamekpor ◽  
Joong-Won Lee ◽  
Nathaniel L. Hepowit ◽  
Cheng Wu ◽  
Clement Charenton ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Protein Quality ◽  
E3 Ligase ◽  
Structure And Function ◽  
Dependent Manner ◽  
Ribosomal Subunits ◽  
Terminal Domain ◽  
Cell Extracts ◽  
And Function

The Ltn1 E3 ligase (listerin in mammals) has emerged as a paradigm for understanding ribosome-associated ubiquitylation. Ltn1 binds to 60S ribosomal subunits to ubiquitylate nascent polypeptides that become stalled during synthesis; among Ltn1’s substrates are aberrant products of mRNA lacking stop codons [nonstop translation products (NSPs)]. Here, we report the reconstitution of NSP ubiquitylation in Neurospora crassa cell extracts. Upon translation in vitro, ribosome-stalled NSPs were ubiquitylated in an Ltn1-dependent manner, while still ribosome-associated. Furthermore, we provide biochemical evidence that the conserved N-terminal domain (NTD) plays a significant role in the binding of Ltn1 to 60S ribosomal subunits and that NTD mutations causing defective 60S binding also lead to defective NSP ubiquitylation, without affecting Ltn1’s intrinsic E3 ligase activity. Finally, we report the crystal structure of the Ltn1 NTD at 2.4-Å resolution. The structure, combined with additional mutational studies, provides insight to NTD’s role in binding stalled 60S subunits. Our findings show that Neurospora extracts can be used as a tool to dissect mechanisms underlying ribosome-associated protein quality control and are consistent with a model in which Ltn1 uses 60S subunits as adapters, at least in part via its NTD, to target stalled NSPs for ubiquitylation.

scholarly journals Crescerin uses a TOG domain array to regulate microtubules in the primary cilium

2015 ◽  
Vol 26 (23) ◽  
pp. 4248-4264 ◽  
Author(s):  
Alakananda Das ◽  
Daniel J. Dickinson ◽  
Cameron C. Wood ◽  
Bob Goldstein ◽  
Kevin C. Slep
Keyword(s):  
Crystal Structure ◽  
Binding Activity ◽  
Structure And Function ◽  
Sensory Disorders ◽  
Tubulin Binding ◽  
Sensory Cilia ◽  
And Function ◽  
Binding Determinants ◽  
Extracellular Environment

Eukaryotic cilia are cell-surface projections critical for sensing the extracellular environment. Defects in cilia structure and function result in a broad range of developmental and sensory disorders. However, mechanisms that regulate the microtubule (MT)-based scaffold forming the cilia core are poorly understood. TOG domain array–containing proteins ch-TOG and CLASP are key regulators of cytoplasmic MTs. Whether TOG array proteins also regulate ciliary MTs is unknown. Here we identify the conserved Crescerin protein family as a cilia-specific, TOG array-containing MT regulator. We present the crystal structure of mammalian Crescerin1 TOG2, revealing a canonical TOG fold with conserved tubulin-binding determinants. Crescerin1's TOG domains possess inherent MT-binding activity and promote MT polymerization in vitro. Using Cas9-triggered homologous recombination in Caenorhabditis elegans, we demonstrate that the worm Crescerin family member CHE-12 requires TOG domain–dependent tubulin-binding activity for sensory cilia development. Thus, Crescerin expands the TOG domain array–based MT regulatory paradigm beyond ch-TOG and CLASP, representing a distinct regulator of cilia structure.

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