scholarly journals Roles of the C-Terminal Amino Acids of Non-Hexameric Helicases: Insights from Escherichia coli UvrD

2021 ◽  
Vol 22 (3) ◽  
pp. 1018
Author(s):  
Hiroaki Yokota
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Single Molecule ◽  
Underlying Mechanism ◽  
Amino Acid Sequences ◽  
E Coli ◽  
X Ray Crystallography ◽  
Terminal Amino

Helicases are nucleic acid-unwinding enzymes that are involved in the maintenance of genome integrity. Several parts of the amino acid sequences of helicases are very similar, and these quite well-conserved amino acid sequences are termed “helicase motifs”. Previous studies by X-ray crystallography and single-molecule measurements have suggested a common underlying mechanism for their function. These studies indicate the role of the helicase motifs in unwinding nucleic acids. In contrast, the sequence and length of the C-terminal amino acids of helicases are highly variable. In this paper, I review past and recent studies that proposed helicase mechanisms and studies that investigated the roles of the C-terminal amino acids on helicase and dimerization activities, primarily on the non-hexermeric Escherichia coli (E. coli) UvrD helicase. Then, I center on my recent study of single-molecule direct visualization of a UvrD mutant lacking the C-terminal 40 amino acids (UvrDΔ40C) used in studies proposing the monomer helicase model. The study demonstrated that multiple UvrDΔ40C molecules jointly participated in DNA unwinding, presumably by forming an oligomer. Thus, the single-molecule observation addressed how the C-terminal amino acids affect the number of helicases bound to DNA, oligomerization, and unwinding activity, which can be applied to other helicases.

scholarly journals Mistranslation of a TGA termination codon as tryptophan in recombinant platelet-derived growth factor expressed in Escherichia coli

1995 ◽  
Vol 309 (2) ◽  
pp. 411-417 ◽  
Author(s):  
K V Lu ◽  
M F Rohde ◽  
A R Thomason ◽  
W C Kenney ◽  
H S Lu
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Growth Factor ◽  
Translation Termination ◽  
Termination Codon ◽  
Platelet Derived Growth Factor ◽  
E Coli ◽  
Translation Termination Codon ◽  
Terminal Amino

The mature 109-amino-acid human platelet-derived growth factor B (PDGF-B) peptide is derived by intracellular processing from a 241-amino-acid precursor synthesized in mammalian cells, with removal of 81 N-terminal and 51 C-terminal amino acids. In order to produce directly the mature 109-amino acid PDGF-B peptide as a recombinant protein in Escherichia coli, a CGA codon at position 110 of a DNA sequence encoding the full-length precursor form of PDGF-B was converted into the translation termination codon TGA by in vitro mutagenesis. Expression of this DNA via a plasmid vector in E. coli resulted in production of two distinct PDGF-B proteins having apparent molecular masses of 15 and 19 kDa, with the latter species predominating. Structural characterization employing N- and C-terminal amino acid sequencing and MS analyses indicated that the 15 kDa protein is the expected 109-amino-acid PDGF-B, and that the 19 kDa protein represents a C-terminal extended PDGF-B containing 160 amino acids. Characterization of a unique tryptic peptide derived from the 19 kDa protein revealed that this longer form of PDGF-B results from mistranslation of the introduced TGA termination codon at position 110 as tryptophan, with translation subsequently proceeding to the naturally occurring TAG termination codon at position 161. Owing to the high rate of translation readthrough of TGA codons in this and occasionally other proteins, it appears that the use of TGA as a translation termination codon for proteins to be expressed in E. coli should be avoided when possible.

Subunit II (b') and Not Subunit I (b) of Photosynthetic ATP Synthases is Equivalent to Subunit b of the ATP Synthases from Nonphotosynthetic Eubacteria. Evidence for a New Assignment of b-Type F0 Subunits

1997 ◽  
Vol 52 (11-12) ◽  
pp. 789-798 ◽  
Author(s):  
Hans-Jürgen Tiburzy ◽  
Richard J. Berzborn
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Structural Feature ◽  
Atp Synthase ◽  
Primary Structure ◽  
Structural Features ◽  
Amino Acid Sequences ◽  
E Coli ◽  
Subunit B ◽  
Atp Synthases

Abstract Subunit I of chloroplast ATP synthase is reviewed until now to be equivalent to subunit b of Escherichia coli ATP synthase, whereas subunit II is suggested to be an additional subunit in photosynthetic ATP synthases lacking a counterpart in E. coli. After publication of some sequences of subunits II a revision of this assignment is necessary. Based on the analysis of 51 amino acid sequences of b-type subunits concerning similarities in primary structure, iso­electric point and a discovered discontinuous structural feature, our data provide evidence that chloroplast subunit II (subunit b' of photosynthetic eubacteria) and not chloroplast subunit I (subunit b of photosynthetic eubacteria) is the equivalent of subunit b of nonphoto­ synthetic eubacteria, and therefore does have a counterpart in e.g. E. coli. In consequence, structural features essential for function should be looked for on subunit II (b').

scholarly journals Role of Burkholderia pseudomallei Sigma N2 in Amino Acids Utilization and in Regulation of Catalase E Expression at the Transcriptional Level

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Duong Thi Hong Diep ◽  
Nguyen Thi Thanh Phuong ◽  
Mya Myintzu Hlaing ◽  
Potjanee Srimanote ◽  
Sumalee Tungpradabkul
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Burkholderia Pseudomallei ◽  
Transcriptional Level ◽  
Chromosome 2 ◽  
E Coli ◽  
Alternative Sigma Factors ◽  
Amino Acid Utilization ◽  
Genes Expression

Burkholderia pseudomallei is the causative agent of melioidosis. The complete genome sequences of this pathogen have been revealed, which explain some pathogenic mechanisms. In various hostile conditions, for example, during nitrogen and amino acid starvation, bacteria can utilize alternative sigma factors such as RpoS and RpoN to modulate genes expression for their adaptation and survival. In this study, we demonstrate that mutagenesis of rpoN2, which lies on chromosome 2 of B. pseudomallei and encodes a homologue of the sigma factor RpoN, did not alter nitrogen and amino acid utilization of the bacterium. However, introduction of B. pseudomallei rpoN2 into E. coli strain deficient for rpoN restored the ability to utilize amino acids. Moreover, comparative partial proteomic analysis of the B. pseudomallei wild type and its rpoN2 isogenic mutant was performed to elucidate its amino acids utilization property which was comparable to its function found in the complementation assay. By contrast, the rpoN2 mutant exhibited decreased katE expression at the transcriptional and translational levels. Our finding indicates that B. pseudomallei RpoN2 is involved in a specific function in the regulation of catalase E expression.

scholarly journals In silico analysis of virulence associated genes in genomes of Escherichia coli strains causing colibacillosis in poultry

2017 ◽  
Vol 61 (4) ◽  
pp. 421-426 ◽  
Author(s):  
Joanna Kołsut ◽  
Paulina Borówka ◽  
Błażej Marciniak ◽  
Ewelina Wójcik ◽  
Arkadiusz Wojtasik ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Virulence Factors ◽  
De Novo ◽  
Protein Sequences ◽  
In Silico Analysis ◽  
Amino Acid Sequences ◽  
Common Disease ◽  
Bacterial Genomes ◽  
E Coli

AbstractIntroduction: Colibacillosis – the most common disease of poultry, is caused mainly by avian pathogenic Escherichia coli (APEC). However, thus far, no pattern to the molecular basis of the pathogenicity of these bacteria has been established beyond dispute. In this study, genomes of APEC were investigated to ascribe importance and explore the distribution of 16 genes recognised as their virulence factors.Material and Methods: A total of 14 pathogenic for poultry E. coli strains were isolated, and their DNA was sequenced, assembled de novo, and annotated. Amino acid sequences from these bacteria and an additional 16 freely available APEC amino acid sequences were analysed with the DIFFIND tool to define their virulence factors.Results: The DIFFIND tool enabled quick, reliable, and convenient assessment of the differences between compared amino acid sequences from bacterial genomes. The presence of 16 protein sequences indicated as pathogenicity factors in poultry resulted in the generation of a heatmap which categorises genomes in terms of the existence and similarity of the analysed protein sequences.Conclusion: The proposed method of detection of virulence factors using the capabilities of the DIFFIND tool may be useful in the analysis of similarities of E. coli and other sequences deriving from bacteria. Phylogenetic analysis resulted in reliable segregation of 30 APEC strains into five main clusters containing various virulence associated genes (VAGs).

scholarly journals Characterization of human and mouse granulocyte-macrophage-colony-stimulating factors derived from Escherichia coli

1987 ◽  
Vol 247 (1) ◽  
pp. 195-199 ◽  
Author(s):  
J L Schrimsher ◽  
K Rose ◽  
M G Simona ◽  
P Wingfield
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Sequences ◽  
Natural Material ◽  
Animal Cells ◽  
Colony Stimulating Factors ◽  
E Coli ◽  
Macrophage Colony ◽  
The One ◽  
Human And Mouse

Human and mouse granulocyte-macrophage-colony-stimulating factors (hGM-CSF and mGM-CSF, respectively), isolated from Escherichia coli cells expressing the corresponding human and mouse genes, have been characterized. The observed properties of the proteins have been compared with those properties which can be deduced from the DNA sequence alone and the published properties of natural GM-CSFs. The purified E. coli-derived proteins were found to have the expected molecular masses, amino acid compositions and N- and C-terminal amino acid sequences. The finding of 70-90% unprocessed N-terminal methionine for both proteins is discussed. The four Cys residues were found to be involved in two intramolecular disulphide bonds, linking the first and third, and second and fourth Cys residues. This disulphide bond arrangement is probably the one existing in natural material, since, although not glycosylated, both E. coli-derived proteins showed biological activity (colony stimulating assay for hGM-CSF, and cell proliferation assay for mGM-CSF) comparable with that reported for the respective proteins purified from animal cells.

scholarly journals Enzymic synthesis of N-acetyl-l-phenylalanine in Escherichia coli K12

1971 ◽  
Vol 124 (5) ◽  
pp. 905-913 ◽  
Author(s):  
R. V. Krishna ◽  
P. R. Krishnaswamy ◽  
D. Rajagopal Rao
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Acetyl Coa ◽  
Ph Optimum ◽  
E Coli ◽  
Enzymic Synthesis ◽  
Escherichia Coli K12

1. Cell-free extracts of Escherichia coli K12 catalyse the synthesis of N-acetyl-l-phenylalanine from acetyl-CoA and l-phenylalanine. 2. The acetyl-CoA–l-phenylalanine α-N-acetyltransferase was purified 160-fold from cell-free extracts. 3. The enzyme has a pH optimum of 8 and catalyses the acetylation of l-phenylalanine. Other l-amino acids such as histidine and alanine are acetylated at slower rates. 4. A transacylase was also purified from E. coli extracts and its substrate specificity studied. 5. The properties of both these enzymes were compared with those of other known amino acid acetyltransferases and transacylases.

Expression and Regulation of the Arsenic Resistance Operon of Acidiphilium multivorum AIU 301 Plasmid pKW301 in Escherichia coli

1998 ◽  
Vol 64 (2) ◽  
pp. 411-418 ◽  
Author(s):  
Katsuhisa Suzuki ◽  
Norio Wakao ◽  
Tetsuya Kimura ◽  
Kazuo Sakka ◽  
Kunio Ohmiya
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Constitutive Expression ◽  
Amino Acid Sequences ◽  
Gene Products ◽  
Arsenic Resistance ◽  
E Coli ◽  
Molecular Weights ◽  
Rna Polymerase Promoter ◽  
Extension Analysis

ABSTRACT The arsenic resistance (ars) operon from plasmid pKW301 of Acidiphilium multivorum AIU 301 was cloned and sequenced. This DNA sequence contains five genes in the following order: arsR, arsD, arsA,arsB, arsC. The predicted amino acid sequences of all of the gene products are homologous to the amino acid sequences of the ars gene products of Escherichia coliplasmid R773 and IncN plasmid R46. The ars operon cloned from A. multivorum conferred resistance to arsenate and arsenite on E. coli. Expression of the arsgenes with the bacteriophage T7 RNA polymerase-promoter system allowedE. coli to overexpress ArsD, ArsA, and ArsC but not ArsR or ArsB. The apparent molecular weights of ArsD, ArsA, and ArsC were 13,000, 64,000, and 16,000, respectively. A primer extension analysis showed that the ars mRNA started at a position 19 nucleotides upstream from the arsR ATG in E. coli. Although the arsR gene of A. multivorum AIU 301 encodes a polypeptide of 84 amino acids that is smaller and less homologous than any of the other ArsR proteins, inactivation of the arsR gene resulted in constitutive expression of the ars genes, suggesting that ArsR of pKW301 controls the expression of this operon.

scholarly journals Simultaneous Binding of Multiple EF-Tu Copies to Translating Ribosomes in Live Escherichia coli

mBio ◽  
2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Mainak Mustafi ◽  
James C. Weisshaar
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Single Molecule ◽  
Ternary Complex ◽  
Elongation Factor ◽  
Ternary Complexes ◽  
Local Concentration ◽  
E Coli ◽  
A Site

ABSTRACT In bacteria, elongation factor Tu is a translational cofactor that forms ternary complexes with aminoacyl-tRNA (aa-tRNA) and GTP. Binding of a ternary complex to one of four flexible L7/L12 units on the ribosome tethers a charged tRNA in close proximity to the ribosomal A site. Two sequential tests for a match between the aa-tRNA anticodon and the current mRNA codon then follow. Because one elongation cycle can occur in as little as 50 ms and the vast majority of aa-tRNA copies are not cognate with the current mRNA codon, this testing must occur rapidly. We present a single-molecule localization and tracking study of fluorescently labeled EF-Tu in live Escherichia coli. Imaging at 2 ms/frame distinguishes 60% slowly diffusing EF-Tu copies (assigned as transiently bound to translating ribosome) from 40% rapidly diffusing copies (assigned as a mixture of free ternary complexes and free EF-Tu). Combining these percentages with copy number estimates, we infer that the four L7/L12 sites are essentially saturated with ternary complexes in vivo. The results corroborate an earlier inference that all four sites can simultaneously tether ternary complexes near the A site, creating a high local concentration that may greatly enhance the rate of testing of aa-tRNAs. Our data and a combinatorial argument both suggest that the initial recognition test for a codon-anticodon match occurs in less than 1 to 2 ms per aa-tRNA copy. The results refute a recent study (A. Plochowietz, I. Farrell, Z. Smilansky, B. S. Cooperman, and A. N. Kapanidis, Nucleic Acids Res 45:926–937, 2016, https://doi.org/10.1093/nar/gkw787) of tRNA diffusion in E. coli that inferred that aa-tRNAs arrive at the ribosomal A site as bare monomers, not as ternary complexes. IMPORTANCE Ribosomes catalyze translation of the mRNA codon sequence into the corresponding sequence of amino acids within the nascent polypeptide chain. Polypeptide elongation can be as fast as 50 ms per added amino acid. Each amino acid arrives at the ribosome as a ternary complex comprising an aminoacyl-tRNA (aa-tRNA), an elongation factor called EF-Tu, and GTP. There are 43 different aa-tRNAs in use, only one of which typically matches the current mRNA codon. Thus, ternary complexes must be tested very rapidly. Here we use fluorescence-based single-molecule methods that locate and track single EF-Tu copies in E. coli. Fast and slow diffusive behavior determines the fraction of EF-Tu copies that are ribosome bound. We infer simultaneous tethering of ~4 ternary complexes to the ribosome, which may facilitate rapid initial testing for codon matching on a time scale of less than 1 to 2 ms per aa-tRNA.

Kynurenine aminotransferase and glutamine transaminase K of Escherichia coli: identity with aspartate aminotransferase

2001 ◽  
Vol 360 (3) ◽  
pp. 617-623 ◽  
Author(s):  
Qian HAN ◽  
Jianmin FANG ◽  
Jianyong LI
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Aspartate Aminotransferase ◽  
Expression System ◽  
Xanthurenic Acid ◽  
Amino Acid Residues ◽  
Terminal Amino Acid ◽  
Kynurenine Aminotransferase ◽  
E Coli ◽  
Terminal Amino

The present study describes the isolation of a protein from Escherichia coli possessing kynurenine aminotransferase (KAT) activity and its identification as aspartate aminotransferase (AspAT). KAT catalyses the transamination of kynurenine and 3-hydroxykynurenine to kynurenic acid and xanthurenic acid respectively, and the enzyme activity can be easily detected in E. coli cells. Separation of the E. coli protein possessing KAT activity through various chromatographic steps led to the isolation of the enzyme. N-terminal sequencing of the purified protein determined its first 10 N-terminal amino acid residues, which were identical with those of the E. coli AspAT. Recombinant AspAT (R-AspAT), homologously expressed in an E. coli/pET22b expression system, was capable of catalysing the transamination of both l-kynurenine (Km = 3mM; Vmax = 7.9μmol·min−1·mg−1) and 3-hydroxy-dl-kynurenine (Km = 3.7mM; Vmax = 1.25μmol·min−1·mg−1) in the presence of pyruvate as an amino acceptor, and exhibited its maximum activity at temperatures between 50–60°C and at a pH of approx. 7.0. Like mammalian KATs, R-AspAT also displayed high glutamine transaminase K activity when l-phenylalanine was used as an amino donor (Km = 8mM; Vmax = 20.6μmol·min−1·mg−1). The exact match of the first ten N-terminal amino acid residues of the KAT-active protein with that of AspAT, in conjunction with the high KAT activity of R-AspAT, provides convincing evidence that the identity of the E. coli protein is AspAT.

scholarly journals Role of Transmembrane Domain and Cytoplasmic Tail Amino Acid Sequences of Influenza A Virus Neuraminidase in Raft Association and Virus Budding

2004 ◽  
Vol 78 (10) ◽  
pp. 5258-5269 ◽  
Author(s):  
Subrata Barman ◽  
Lopa Adhikary ◽  
Alok K. Chakrabarti ◽  
Carl Bernas ◽  
Yoshihiro Kawaoka ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Influenza A ◽  
Transmembrane Domain ◽  
Amino Acid Sequences ◽  
Type Ii ◽  
Virus Growth ◽  
Transmembrane Glycoprotein ◽  
Virus Life Cycle

ABSTRACT Influenza virus neuraminidase (NA), a type II transmembrane glycoprotein, possesses receptor-destroying activity and thereby facilitates virus release from the cell surface. Among the influenza A viruses, both the cytoplasmic tail (CT) and transmembrane domain (TMD) amino acid sequences of NA are highly conserved, yet their function(s) in virus biology remains unknown. To investigate the role of amino acid sequences of the CT and TMD on the virus life cycle, we systematically mutagenized the entire CT and TMD of NA by converting two to five contiguous amino acids to alanine. In addition, we also made two chimeric NA by replacing the CT proximal one-third amino acids of the NA TMD [NA(1T2N)NA] and the entire NA TMD (NATRNA) with that of human transferrin receptor (TR) (a type II transmembrane glycoprotein). We rescued transfectant mutant viruses by reverse genetics and examined their phenotypes. Our results show that all mutated and chimeric NAs could be rescued into transfectant viruses. Different mutants showed pleiotropic effects on virus growth and replication. Some mutants (NA2A5, NA3A7, and NA4A10) had little effect on virus growth while others (NA3A2, NA5A27, and NA5A31) produced about 50- to 100-fold-less infectious virus and still some others (NA5A14, NA4A19, and NA4A23) exhibited an intermediate phenotype. In general, mutations towards the ectodomain-proximal sequences of TMD progressively caused reduction in NA enzyme activity, affected lipid raft association, and attenuated virus growth. Electron microscopic analysis showed that these mutant viruses remained aggregated and bound to infected cell surfaces and could be released from the infected cells by bacterial NA treatment. Moreover, viruses containing mutations in the extreme N terminus of the CT (NA3A2) as well as chimeric NA containing the TMD replaced partially [NA(1T2N)NA] or fully (NATRNA) with TR TMD caused reduction in virus growth and exhibited the morphological phenotype of elongated particles. These results show that although the sequences of NA CT and TMD per se are not absolutely essential for the virus life cycle, specific amino acid sequences play a critical role in providing structural stability, enzyme activity, and lipid raft association of NA. In addition, aberrant morphogenesis including elongated particle formation of some mutant viruses indicates the involvement of NA in virus morphogenesis and budding.

Sign in / Sign up

Export Citation Format

Share Document