scholarly journals Characterization of redox properties of FAD cofactor of Thermotoga maritima thioredoxin reductase

Chemija ◽  
2020 ◽  
Vol 31 (3) ◽  
Author(s):  
Benjaminas Valiauga ◽  
Nicolas Rouhier ◽  
Jean-Pierre Jacquot ◽  
Narimantas Čėnas
Keyword(s):  
Amino Acid ◽  
Redox Potential ◽  
Thermotoga Maritima ◽  
Thioredoxin Reductase ◽  
Amino Acid Sequences ◽  
Redox Properties ◽  
Redox Couple ◽  
E Coli ◽  
Standard Redox Potential

The fluorescence properties of FAD of Thermotoga maritima thioredoxin reductase (TmTR), taken together with the amino acid sequences and structures of similar TRs, are consistent with the interdomain rotation in the catalysis of TmTR. The standard redox potential of FAD of TmTR, –0.230 V, determined by the reactions with 3-acetylpyridine adenine dinucleotide (APAD+/APADH) redox couple, is close to that of E. coli TR. During the reduction of duroquinone with TmTR, the transient formation of neutral FAD semiquinone, and, possibly, FADH2–NAD+ complex was observed. This shows that in spite of obligatory twoelectron (hydride)-transfer between NADH and physiological disulfide oxidants, the FAD cofactor of TmTR may exist under a stable semiquinone form.

scholarly journals Redox properties and cross-linking of the dithiol/disulphide active sites of mammalian protein disulphide-isomerase

1991 ◽  
Vol 275 (2) ◽  
pp. 341-348 ◽  
Author(s):  
H C Hawkins ◽  
M de Nardi ◽  
R B Freedman
Keyword(s):  
Redox Potential ◽  
Active Site ◽  
Active Sites ◽  
Residual Activity ◽  
Redox Properties ◽  
Redox Couple ◽  
Hill Coefficient ◽  
Cross Linking ◽  
Standard Redox Potential ◽  
Reactive Groups

1. The redox properties of the active-site dithiol/disulphide groups of PDI were determined by equilibrating the enzyme with an excess of GSH + GSSG, rapidly alkylating the dithiol form of the enzyme to inactivate it irreversibly, and determining the proportion of the disulphide form by measuring the residual activity under standard conditions. 2. The extent of reduction varied with the applied redox potential; to a first approximation, the data fitted a model in which all the enzyme dithiol/disulphide groups are independent and equivalent and the equilibrium constant between these sites and the GSH/GSSG redox couple is 42 microM at pH 7.5. 3. The standard redox potential for PDI active-site dithiol/disulphide couples was calculated from this result and found to be -0.11 V; hence PDI is a stronger oxidant and weaker reductant than GSH, nicotinamide cofactors, thioredoxin and dithiothreitol. 4. The redox equilibrium data for PDI with the GSH/GSSG redox couple showed sigmoidal deviations from linearity. The sigmoidicity could be modelled closely by assuming a Hill coefficient of 1.5. 5. This evidence of co-operative interactions between the four active sites in a PDI dimer was extended by studying the reaction between PDI and homobifunctional alkylating agents with various lengths between the reactive groups. A species whose electrophoretic mobility suggested it contained an intrachain cross-link was observed in all cases, whereas there was no evidence for cross-linking between the chains of the PDI homodimer. Most effective cross-linking was achieved with reagents containing five or more methylene spacer groups, implying a minimum distance of 1.6 nm (16 A) between the active-site reactive groups within the two thioredoxin-like domains of the PDI polypeptide.

scholarly journals Characterization of a Bordetella pertussisDiaminopimelate (DAP) Biosynthesis Locus Identifies dapC, a Novel Gene Coding for anN-Succinyl-l,l-DAP Aminotransferase

2000 ◽  
Vol 182 (13) ◽  
pp. 3626-3631 ◽  
Author(s):  
Thilo M. Fuchs ◽  
Boris Schneider ◽  
Karin Krumbach ◽  
Lothar Eggeling ◽  
Roy Gross
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequences ◽  
Open Reading Frames ◽  
Binding Motif ◽  
Aminotransferase Activity ◽  
Phosphate Binding ◽  
E Coli ◽  
Gene Coding ◽  
Sequence Similarities

ABSTRACT The functional complementation of two Escherichia colistrains defective in the succinylase pathway ofmeso-diaminopimelate (meso-DAP) biosynthesis with a Bordetella pertussis gene library resulted in the isolation of a putative dap operon containing three open reading frames (ORFs). In line with the successful complementation of the E. coli dapD and dapE mutants, the deduced amino acid sequences of two ORFs revealed significant sequence similarities with the DapD and DapE proteins of E. coli and many other bacteria which exhibit tetrahydrodipicolinate succinylase and N-succinyl-l,l-DAP desuccinylase activity, respectively. The first ORF within the operon showed significant sequence similarities with transaminases and contains the characteristic pyridoxal-5′-phosphate binding motif. Enzymatic studies revealed that this ORF encodes a protein withN-succinyl-l,l-DAP aminotransferase activity converting N-succinyl-2-amino-6-ketopimelate, the product of the succinylase DapD, to N-succinyl-l,l-DAP, the substrate of the desuccinylase DapE. Therefore, this gene appears to encode the DapC protein of B. pertussis. Apart from the pyridoxal-5′-phosphate binding motif, the DapC protein does not show further amino acid sequence similarities with the only other known enzyme with N-succinyl-l,l-DAP aminotransferase activity, ArgD of E. coli.

scholarly journals Identification and Characterization of thefis Operon in Enteric Bacteria

1998 ◽  
Vol 180 (22) ◽  
pp. 5932-5946 ◽  
Author(s):  
Michael B. Beach ◽  
Robert Osuna
Keyword(s):  
Amino Acid ◽  
Genomic Sequence ◽  
Erwinia Carotovora ◽  
Enteric Bacteria ◽  
Integration Host Factor ◽  
Amino Acid Sequences ◽  
Reading Frame ◽  
E Coli

ABSTRACT The small DNA binding protein Fis is involved in several different biological processes in Escherichia coli. It has been shown to stimulate DNA inversion reactions mediated by the Hin family of recombinases, stimulate integration and excision of phage λ genome, regulate the transcription of several different genes including those of stable RNA operons, and regulate the initiation of DNA replication at oriC. fis has also been isolated from Salmonella typhimurium, and the genomic sequence of Haemophilus influenzae reveals its presence in this bacteria. This work extends the characterization of fis to other organisms. Very similar fis operon structures were identified in the enteric bacteria Klebsiella pneumoniae, Serratia marcescens, Erwinia carotovora, andProteus vulgaris but not in several nonenteric bacteria. We found that the deduced amino acid sequences for Fis are 100% identical in K. pneumoniae, S. marcescens,E. coli, and S. typhimurium and 96 to 98% identical when E. carotovora and P. vulgaris Fis are considered. The deduced amino acid sequence forH. influenzae Fis is about 80% identical and 90% similar to Fis in enteric bacteria. However, in spite of these similarities, the E. carotovora, P. vulgaris, and H. influenzae Fis proteins are not functionally identical. An open reading frame (ORF1) precedingfis in E. coli is also found in all these bacteria, and their deduced amino acid sequences are also very similar. The sequence preceding ORF1 in the enteric bacteria showed a very strong similarity to the E. coli fis P region from −53 to +27 and the region around −116 containing an ihfbinding site. Both β-galactosidase assays and primer extension assays showed that these regions function as promoters in vivo and are subject to growth phase-dependent regulation. However, their promoter strengths vary, as do their responses to Fis autoregulation and integration host factor stimulation.

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 Characterization of the Gallate Dioxygenase Gene: Three Distinct Ring Cleavage Dioxygenases Are Involved in Syringate Degradation by Sphingomonas paucimobilis SYK-6

2005 ◽  
Vol 187 (15) ◽  
pp. 5067-5074 ◽  
Author(s):  
Daisuke Kasai ◽  
Eiji Masai ◽  
Keisuke Miyauchi ◽  
Yoshihiro Katayama ◽  
Masao Fukuda
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequences ◽  
Terminal Region ◽  
Ring Cleavage ◽  
Sphingomonas Paucimobilis ◽  
Acid Protein ◽  
Demethylation Pathway ◽  
Dioxygenase Gene ◽  
Amino Acid Protein

ABSTRACT Sphingomonas paucimobilis SYK-6 converts vanillate and syringate to protocatechuate (PCA) and 3-O-methylgallate (3MGA) in reactions with the tetrahydrofolate-dependent O-demethylases LigM and DesA, respectively. PCA is further degraded via the PCA 4,5-cleavage pathway, whereas 3MGA is metabolized via three distinct pathways in which PCA 4,5-dioxygenase (LigAB), 3MGA 3,4-dioxygenase (DesZ), and 3MGA O-demethylase (LigM) are involved. In the 3MGA O-demethylation pathway, LigM converts 3MGA to gallate, and the resulting gallate appears to be degraded by a dioxygenase other than LigAB or DesZ. Here, we isolated the gallate dioxygenase gene, desB, which encodes a 418-amino-acid protein with a molecular mass of 46,843 Da. The amino acid sequences of the N-terminal region (residues 1 to 285) and the C-terminal region (residues 286 to 418) of DesB exhibited ca. 40% and 27% identity with the sequences of the PCA 4,5-dioxygenase β and α subunits, respectively. DesB produced in Escherichia coli was purified and was estimated to be a homodimer (86 kDa). DesB specifically attacked gallate to generate 4-oxalomesaconate as the reaction product. The Km for gallate and the V max were determined to be 66.9 ± 9.3 μM and 42.7 ± 2.4 U/mg, respectively. On the basis of the analysis of various SYK-6 mutants lacking the genes involved in syringate degradation, we concluded that (i) all of the three-ring cleavage dioxygenases are involved in syringate catabolism, (ii) the pathway involving LigM and DesB plays an especially important role in the growth of SYK-6 on syringate, and (iii) DesB and LigAB are involved in gallate degradation.

Functional and Structural Characterization of Acquired Pan-Aminoglycoside Resistance 16S rRNA Methyltransferase NpmB1

2021 ◽  
Author(s):  
Akito Kawai ◽  
Masahiro Suzuki ◽  
Kentaro Tsukamoto ◽  
Yusuke Minato ◽  
Yohei Doi
Keyword(s):  
Amino Acid ◽  
16S Rrna ◽  
Amino Acid Identity ◽  
Single Amino Acid ◽  
Aminoglycoside Resistance ◽  
E Coli ◽  
The United Kingdom ◽  
Amino Acid Variant ◽  
A Site

Post-translational methylation of the A site of 16S rRNA at position A1408 leads to pan-aminoglycoside resistance encompassing both 4,5- and 4,6-disubstituted 2-deoxystreptamine (DOS) aminoglycosides. To date, NpmA is the only acquired enzyme with such function. Here, we present function and structure of NpmB1 whose sequence was identified in Escherichia coli genomes registered from the United Kingdom. NpmB1 possesses 40% amino acid identity with NpmA1 and confers resistance to all clinically relevant aminoglycosides including 4,5-DOS agents. Phylogenetic analysis of NpmB1 and NpmB2, its single amino acid variant, revealed that the encoding gene was likely acquired by E. coli from a soil bacterium. The structure of NpmB1 suggests that it requires a structural change of the β6/7 linker in order to bind to 16S rRNA. These findings establish NpmB1 and NpmB2 as the second group of acquired pan-aminoglycoside resistance 16S rRNA methyltransferases.

scholarly journals Molecular characterization of Prunus necrotic ringspot virus isolated from rose in Brazil

2015 ◽  
Vol 45 (12) ◽  
pp. 2197-2200 ◽  
Author(s):  
Thor Vinícius Martins Fajardo ◽  
Monique Bezerra Nascimento ◽  
Marcelo Eiras ◽  
Osmar Nickel ◽  
Gilvan Pio-Ribeiro
Keyword(s):  
Amino Acid ◽  
Molecular Characterization ◽  
Molecular Analysis ◽  
Nucleotide Sequences ◽  
Amino Acid Sequences ◽  
Causal Agent ◽  
Ringspot Virus ◽  
Prunus Necrotic Ringspot Virus ◽  
First Time

ABSTRACT: There is no molecular characterization of Brazilian isolates of Prunus necrotic ringspot virus (PNRSV), except for those infecting peach. In this research, the causal agent of rose mosaic was determined and the movement (MP) and coat (CP) protein genes of a PNRSV isolate from rose were molecularly characterized for the first time in Brazil. The nucleotide and deduced amino acid sequences of MP and CP complete genes were aligned and compared with other isolates. Molecular analysis of the MP and CP nucleotide sequences of a Brazilian PNRSV isolate from rose and others from this same host showed highest identities of 96.7% and 98.6%, respectively, and Rose-Br isolate was classified in PV32 group.

scholarly journals In vitro and In Silico Approach For Characterization of Antimicrobial Peptide From Probiotics Against Staphylococcus Aureus and Escherichia Coli

2021 ◽  
Author(s):  
Amrutha Bindu ◽  
Lakshmi Devi
Keyword(s):  
Amino Acid ◽  
Antimicrobial Peptide ◽  
Lactobacillus Plantarum ◽  
Exchange Chromatography ◽  
Amino Acid Sequences ◽  
Proteinase K ◽  
Kinetic Assay ◽  
Wide Range

Abstract The focus of present study was to characterize antimicrobial peptide produced by probiotic cultures, Enterococcus durans DB-1aa (MCC4243), Lactobacillus plantarum Cu2-PM7 (MCC4246) and Lactobacillus fermentum Cu3-PM8 (MCC4233) against Staphylococus aureus and E. coli. The growth kinetic assay revealed 24 h of incubation to be optimum for bacteriocin production. The partially purified compound after ion-exchange chromatography was found to be thermoresistant and stable under wide range of pH. The compound was sensitive to proteinase-K, but resistant to trypsin, a-amylase and lipase. The apparent molecular weight of bacteriocin from MCC4243 and MCC4246 was found to be 3.5 KDa. Translated partial amino acid sequence of plnA gene in MCC4246 displayed 48 amino acid sequences showing 100% similarity with plantaricin A of Lactobacillus plantarum (WP_0036419). The sequence revealed 7 β sheets, 6 α sheets, 6 predicted coils and 9 predicted turns. The functions on cytoplasm show 10.82 isoelectric point and 48.6% hydrophobicity. The molecular approach of using Geneious Prime software and protein prediction data base for characterization of bacteriocin is novel and predicts “KSSAYSLQMGATAIKQVKKLFKKWGW” as peptide responsible for antimicrobial activity. The study provides information about broad spectrum bacteriocin in native probiotic culture and paves a way towards its application in functional foods as biopreservative agents.

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