scholarly journals Frameshifts and wild-type protein sequences are always highly similar because the genetic code is optimal for frameshift tolerance

2016 ◽  
Author(s):  
Xiaolong Wang ◽  
Quanjiang Dong ◽  
Gang Chen ◽  
Jianye Zhang ◽  
Yongqiang Liu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Genetic Code ◽  
Protein Sequences ◽  
Loss Of Function ◽  
Wild Type ◽  
Standard Genetic Code ◽  
Type Protein ◽  
Wild Type Protein ◽  
Codon Pairs ◽  
Reading Frames

AbstractFrameshift mutation yields truncated, dysfunctional product proteins, leading to loss-of-function, genetic disorders or even death. Frameshift mutations have been considered as mostly harmful and of little importance for the molecular evolution of proteins. Frameshift protein sequences, encoded by the alternative reading frames of a coding gene, have been therefore considered as meaningless. However, existing studies had shown that frameshift genes/proteins are widely existing and sometimes functional. It is puzzling how a frameshift kept its structure and functionality while its amino-acid sequence is changed substantially. Here we demonstrate that the protein sequences of the frameshifts are highly conservative when compared with the wild-type protein sequence, and the similarities among the three protein sequences encoded in the three reading frames of a coding gene are defined mainly by the genetic code. In the standard genetic code, amino acid substitutions assigned to frameshift codon substitutions are far more conservative than those assigned to random substitutions. The frameshift tolerability of the standard genetic code ranks in the top 1.0-5.0% of all possible genetic codes, showing that the genetic code is optimal in terms of frameshift tolerance. In some higher species, the shiftability is further optimized at gene- or genome-level by a biased usage of codons and codon pairs, in which frameshift-tolerable codons/codon pairs are overrepresented in their genomes.

scholarly journals An Amino Acid Substitution at Position 740 in σ70 of Ralstonia solanacearum Strain OE1-1 Affects Its In Planta Growth

2008 ◽  
Vol 74 (18) ◽  
pp. 5841-5844 ◽  
Author(s):  
Ayami Kanda ◽  
Kazuhiro Tsuneishi ◽  
Ai Mori ◽  
Kouhei Ohnishi ◽  
Akinori Kiba ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Ralstonia Solanacearum ◽  
Wild Type ◽  
In Planta ◽  
Solanacearum Strain ◽  
Type Protein ◽  
Wild Type Protein ◽  
Negative Dominance

ABSTRACT Growth of Ralstonia solanacearum strain OE1-1 in roots after invasion is required for virulence. An Arg740Cys substitution in σ70 of OE1-1 resulted in loss of in planta growth and virulence. The negative dominance of mutant σ70 over the wild-type protein suggested that the amino acid substitution may affect the in planta growth of OE1-1, leading to a lack of virulence.

scholarly journals Dynamics of the Peripheral Membrane Protein P2 from Human Myelin Measured by Neutron Scattering—A Comparison between Wild-Type Protein and a Hinge Mutant

PLoS ONE ◽  
2015 ◽  
Vol 10 (6) ◽  
pp. e0128954 ◽  
Author(s):  
Saara Laulumaa ◽  
Tuomo Nieminen ◽  
Mari Lehtimäki ◽  
Shweta Aggarwal ◽  
Mikael Simons ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Neutron Scattering ◽  
Wild Type ◽  
Type Protein ◽  
Wild Type Protein ◽  
Peripheral Membrane Protein

Two novel mutations in Gli-similar 3 in patients with congenital hypothyroidism and thyroid dysgenesis

2021 ◽  
Author(s):  
Jie Lan ◽  
Chunhui Sun ◽  
Xinping Liang ◽  
Ruixin Ma ◽  
Yuhua Ji ◽  
...  
Keyword(s):  
Congenital Hypothyroidism ◽  
Transcriptional Activation ◽  
Luciferase Assay ◽  
Expression Vectors ◽  
Luciferase Reporter ◽  
Dominant Negative Effect ◽  
Wild Type ◽  
Thyroid Dysgenesis ◽  
Type Protein ◽  
Wild Type Protein

Abstract Background: Thyroid dysgenesis (TD) is the main cause of congenital hypothyroidism (CH). As variants of the transcription factor Gli-similar 3 (GLIS3) have been associated with CH and GLIS3 is one of candidate genes of TD, we screened and characterized GLIS3 mutations in Chinese patients with CH and TD.Methods: To detect mutations, we sequenced all GLIS3 exons in the peripheral blood genomic DNA isolated from 50 patients with TD and 100 healthy individuals. Wild-type and mutant expression vectors of Glis3 were constructed. Quantitative real-time PCR, western blotting, and double luciferase assay were performed to investigation the effect of the mutations on GLIS3 protein function and transcriptional activation.Results: Two novel heterozygous missense mutations, c.2710G>A (p.G904R) and c.2507C>A (p.P836Q), were detected in two unrelated patients. Functional studies revealed that p.G904R expression was 59.95% lower and p.P836Q was 31.23% lower than wild-type GLIS3 mRNA expression. The p.G904R mutation also resulted in lower GLIS3 protein expression compared with that encoded by wild-type GLIS3. Additionally, the luciferase reporter assay revealed that p.G904R mediated impaired transcriptional activation compared with the wild-type protein (p < 0.05) but did not have a dominant-negative effect on the wild-type protein.Conclusions: We for the first time screened and characterized the function of GLIS3 mutations in Chinese individuals with CH and TD. Our study not only broadens the GLIS3 mutation spectrum, but also provides further evidence that GLIS3 defects cause TD.

scholarly journals Ribosome Evolution and Structural Capacitance

2019 ◽  
Author(s):  
Ashley M Buckle ◽  
Malcolm Buckle
Keyword(s):  
Amino Acid ◽  
Genetic Code ◽  
Protein Evolution ◽  
Bioinformatic Analysis ◽  
Amino Acid Usage ◽  
Loss Of Function ◽  
Gain Of Function ◽  
Acceptor Stem ◽  
Ribosome Evolution ◽  
Disordered Regions

In addition to the canonical loss-of-function mutations, mutations in proteins may additionally result in gain-of-function through the binary activation of cryptic &lsquo;structural capacitance elements&rsquo;. Our previous bioinformatic analysis allowed us to propose a new mechanism of protein evolution - structural capacitance &ndash; that arises via the generation of new elements of microstructure upon mutations that cause a disorder-to-order (DO) transition in previously disordered regions of proteins. Here we propose that the DO transition is a necessary follow-on from expected early codon-anticodon and tRNA acceptor stem-amino acid usage, via the accumulation of structural capacitance elements - reservoirs of disorder in proteins. We develop this argument further to posit that structural capacitance is an inherent consequence of the evolution of the genetic code.

scholarly journals Effect of Structural Changes Induced by Deletion of 54FLRAPSWF61 Sequence in αB-Crystallin on Chaperone Function and Anti-Apoptotic Activity

2021 ◽  
Vol 22 (19) ◽  
pp. 10771
Author(s):  
Sundararajan Mahalingam ◽  
Srabani Karmakar ◽  
Puttur Santhoshkumar ◽  
Krishna K. Sharma
Keyword(s):  
Deletion Mutant ◽  
Mutant Protein ◽  
Wild Type ◽  
Chaperone Function ◽  
Type Protein ◽  
Wild Type Protein ◽  
Cytotoxicity Studies ◽  
Αb Crystallin ◽  
Apoptotic Activity ◽  
Subunit Organization

Previously, we showed that the removal of the 54–61 residues from αB-crystallin (αBΔ54–61) results in a fifty percent reduction in the oligomeric mass and a ten-fold increase in chaperone-like activity. In this study, we investigated the oligomeric organization changes in the deletion mutant contributing to the increased chaperone activity and evaluated the cytoprotection properties of the mutant protein using ARPE-19 cells. Trypsin digestion studies revealed that additional tryptic cleavage sites become susceptible in the deletion mutant than in the wild-type protein, suggesting a different subunit organization in the oligomer of the mutant protein. Static and dynamic light scattering analyses of chaperone–substrate complexes showed that the deletion mutant has more significant interaction with the substrates than wild-type protein, resulting in increased binding of the unfolding proteins. Cytotoxicity studies carried out with ARPE-19 cells showed an enhancement in anti-apoptotic activity in αBΔ54–61 as compared with the wild-type protein. The improved anti-apoptotic activity of the mutant is also supported by reduced caspase activation and normalization of the apoptotic cascade components level in cells treated with the deletion mutant. Our study suggests that altered oligomeric assembly with increased substrate affinity could be the basis for the enhanced chaperone function of the αBΔ54–61 protein.

scholarly journals Expression of the Schwanniomyces occidentalis SWA2 amylase in Saccharomyces cerevisiae: role of N-glycosylation on activity, stability and secretion

1998 ◽  
Vol 329 (1) ◽  
pp. 65-71 ◽  
Author(s):  
Esther YÁÑEZ ◽  
A. Teresa CARMONA ◽  
Mercedes TIEMBLO ◽  
Antonio JIMÉNEZ ◽  
María FERNÁNDEZ-LOBATO
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Catalytic Efficiency ◽  
Extracellular Enzyme ◽  
Site Directed Mutagenesis ◽  
Activity Levels ◽  
Wild Type ◽  
Schwanniomyces Occidentalis ◽  
Type Protein ◽  
Wild Type Protein

The role of N-linked glycosylation on the biological activity of Schwanniomyces occidentalis SWA2 α-amylase, as expressed in Saccharomyces cerevisiae, was analysed by site-directed mutagenesis of the two potential N-glycosylation sites, Asn-134 and Asn-229. These residues were replaced by Ala or Gly individually or in various combinations and the effects on the activity, secretion and thermal stability of the enzyme were studied. Any Asn-229 substitution caused a drastic decrease in activity levels of the extracellular enzyme. In contrast, substitutions of Asn-134 had little or no effect. The use of antibodies showed that α-amylase was secreted in all the mutants tested, although those containing substitutions at Asn-229 seemed to have a lower rate of synthesis and/or higher degradation than the wild-type strain. α-Amylases with substitution at Asn-229 had a 2 kDa lower molecular mass than the wild-type protein, as did the wild-type protein itself after treatment with endoglycosidase F. These findings indicate that Asn-229 is the single glycosylated residue in SWA2. Thermostability analysis of both purified wild-type (T50 = 50 °C, where T50 is the temperature resulting in 50% loss of activity) and mutant enzymes indicated that removal of carbohydrate from the 229 position results in a decrease of approx. 3 °C in the T50 of the enzyme. The Gly-229 mutation does not change the apparent affinity of the enzyme for starch (Km) but decreases to 1/22 its apparent catalytic efficiency (kcat/Km). These results therefore indicate that glycosylation at the 229 position has an important role in the extracellular activity levels, kinetics and stability of the Sw. occidentalis SWA2 α-amylase in both its wild-type and mutant forms.

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