OBJECTIVETo clone the recombinant fusion gene of Escherichia coli heat-liable enterotoxin B subunit (Ltb) and Actinobacillus actinomycetemcomitans fimbria associative protein (Fap).

METHODSTwo couples of primers were designed for PCR according to the known sequence of ltb and fap. The ltb and fap gene were obtained by amplification PCR technique from plasmid EWD299 of Escherichia coli and Actinobacillus actinomycetemcomitans 310 DNA respectively, and fused them by PCR. The fusion gene ltb-fap were cloning into plasmid pET28a(+). The recombined plasmid pET28a ltb-fap was transformed into Escherichia coli DH5alpha. The recombinant was screened and identified by restriction enzyme and PCR. The cloned gene was sequenced.

RESULTSThe ltb-fap about 531bp in size was obtained successfully, and identified by PCR, restrictive enzyme and sequence analysis.

CONCLUSIONThe vector of pET28a ltb-fap was obtained.

Aggregatibacter actinomycetemcomitans ; Bacterial Toxins ; Cloning, Molecular ; Cloning, Organism ; Enterotoxins ; Escherichia coli ; Escherichia coli Proteins ; Hot Temperature ; Plasmids ; Polymerase Chain Reaction ; Recombinant Fusion Proteins ; Sequence Analysis

OBJECTIVETo construct a rapid and high-throughput assay for identifying recombinant bacteria based on mass spectrometry.

METHODSMatrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) techniques were used to identify 12 recombinant proteins (10 of Yersinia pestis, 1 of Campylobacter jejuni and 1 of Helicobacter pylori). A classification model for the various phase of recombinant bacteria was established, optimized and validated, using MALDI-TOF MS-ClinProTools system. The differences in the peptide mass spectra were analyzed by using Biotyper and FlexAnalysis softwares.

RESULTSModels of GA, SNN, and QC were established. After optimizing the parameters, the GA recognition model showed good classification capabilities: RC=100%, mean CVA=98.7% (the CVA was 96.4% in phase 1, 100% in phase 2, 98.4% in phase 3, and 100% in phase 4, respectively) and PPV=95%. This model can be used to classify the bacteria and their recombinant, which only requires 3.7×103 cells for analysis. The total time needed is only 10 min from protein extraction to reporting the result for one sample. Furthermore, this assay can automatically detect and test 96 samples concurrently. A total of 48 specific peaks (9, 16, 9, and 14 for the four stages, respectively) was found in the various phase of recombinant bacteria.

CONCLUSIONMALDI-TOF MS can be used as a fast, accurate, and high-throughput method to identify recombinant bacteria, which provide a new ideas not only for recombinant bacteria but also for the identification of mutant strains and bioterrorism pathogens.

Bacterial Proteins ; analysis ; Cloning, Molecular ; Escherichia coli ; Mass Spectrometry ; Organisms, Genetically Modified ; Peptide Mapping ; Recombinant Proteins ; analysis

OBJECTIVETo detect the "high pathogenicity island" of Yersinia enterocolitica WA in E. coli and the to provide evidence for theory base of bacterial evolution process and the different structures in different E. coil.

METHODSPolymerase chain reaction (PCR), nucleic acid hybridization in situ were used to detect and identify HPI. DNA sequencing was used to compare the gene homology of HPI among E. coli with Yersinia enterocolitica (Yen).

RESULTSThe irp2 and fyua genes of Yen HPI were investigated in E. coli strains. Among them, 30 strains were isolated from 93 Enterotoxigenic E. coli (ETEC) strains and 3 strains were positive in 10 strains Enteropathogenic (EPEC). HPI was also detected in Enteroaggregative E. coli (EAggEC) strain. In most of these isolates, HPI was bordered by an asntRNA locus, as in Yersinia sp. Through sequential comparison, the gene sequence homology was higher between in EPEC and EAggEC than ETEC and Yersinia enterocolica.

CONCLUSIONSETEC, EPEC and EAggEC were pathogenicity bacterias and many of them harboring HPI of Yen and the HPI had the same position in E. coli chromosome as Yersinia enterocolitica but the diversity of structure and sequence in these E. coli might suggest that the HPI of these different serotype E. coli were from different ancient bacterias. At the same time, the high positivity rate of HPI in E. coli might be crucial to virulence change, virulence evolution and virulence regulation in E. coli.

Bacterial Proteins ; analysis ; genetics ; Enterotoxins ; genetics ; Escherichia coli ; genetics ; pathogenicity ; Escherichia coli Infections ; microbiology ; Genes, Bacterial ; Receptors, Cell Surface ; genetics ; Virulence ; genetics ; Yersinia enterocolitica ; genetics ; pathogenicity

In this study, the association between virulence genotypes and phylogenetic groups among Escherichia (E.) coli isolates obtained from pet dogs and cats with cystitis was detected, and fingerprinting methods were used to explore the relationship among strains. Forty uropathogenic E. coli (UPEC) isolated from dogs (n = 30) and cats (n = 10) in Italy were analysed by polymerase chain reaction (PCR) for the presence of virulence factors and their classification into phylogenetic groups. The same strains were characterized by repetitive extragenic palindromic (REP)- and enterobacterial repetitive intergenic consensus (ERIC)-PCR techniques. We found a high number of virulence factors such as fimbriae A, S fimbriae (sfa) and cytotoxic necrotizing factor 1 (cnf1) significantly associated with phylogenetic group B2. We demonstrated a high correlation between alpha-hemolysin A and pyelonephritis C, sfa, and cnf1 operons, confirming the presence of pathogenicity islands in these strains. In addition, UPEC belonging to group B2 harboured a greater number of virulence factors than strains from phylogenetic groups A, B1, and D. REP- and ERIC-PCR grouped the UPEC isolates into two major clusters, the former grouping E. coli strains belonging to phylogenetic group B2 and D, the latter grouping those belonging to groups A and B1. Given the significant genetic variability among the UPEC strains found in our study, it can be hypothesized that no specific genotype is responsible for cystitis in cats or dogs.
Animals ; Bacterial Proteins/analysis ; Bacterial Toxins/analysis ; Cat Diseases/microbiology ; Cats ; Cystitis/*microbiology ; Dog Diseases/microbiology ; Dogs ; Escherichia coli Infections/complications/microbiology/*veterinary ; Escherichia coli Proteins/analysis ; Female ; Genetic Variation ; Hemolysin Proteins/analysis ; Italy ; Male ; Operon ; Phylogeny ; Polymerase Chain Reaction ; Pyelonephritis/*microbiology ; Uropathogenic Escherichia coli/classification/*genetics/i ; Virulence Factors/*genetics

Dragline spider silk produced from Nephilia clavipes major ampullate is a natural fibrous protein with specific mechanical properties such as high tensile strength and elasticity. Synthetic gene monomer encoding recombinant spider silk protein, based on the known repetitive protein sequence and partial cDNA sequence of dragline silk, was constructed and expressed. DNA monomer sequences were multimerized to encode high molecular weight synthetic spider silks using a "head-to-tail" construction strategy. Multimer was cloned into pET30a(+), a prokaryotic high potency expression vector, and induced with IPTG. The protein from 8-unit repeat was produced in Escherichia coli at levels up to 20 mg/L. The protein was easily purified with high recovery by using an metal ion affinity chromatography and purity was over 90%. The results of SDS-PAGE and Western blot suggested that the mass of the expression product was about 37 kD. This value and amino acid analysis were consistent with those of theoretic calculation.
Amino Acid Sequence ; Amino Acids ; analysis ; Base Sequence ; Escherichia coli ; genetics ; Fibroins ; Molecular Sequence Data ; Molecular Weight ; Proteins ; analysis ; genetics ; isolation & purification ; Recombinant Proteins ; analysis ; isolation & purification

Pyrosequencing is a tool based on bioluminescence reaction for real-time analyzing DNA sequences. The sensitivity of pyrosequencing mainly depends on luciferase in reaction mixture. However, the instability of pyrosequencing reagents caused by fragile wild Photinus pyralis luciferase (PpL) in conventional pyrosequencing usually leads to unsatisfied results, which limits the application of pyrosequencing. In order to improve the stability of pyrosequencing reagents, the coding sequences of mutant thermostable Luciola lateralis luciferase (rt-LlL) was synthesized, and inserted into the plasmid of pET28a(+) to express the thermostable rt-LlL with a 6 x His-tag in the N terminal. The purified rt-LlL with the molecular mass of 60 kDa was obtained by Ni-affinity chromatography. The specific activity of rt-LlL was determined as 4.29 x 10(10) RLU/mg. Moreover, the thermostability of rt-LlL was investigated, and the results showed that rt-LlL had activity at 50 degrees C, and remained 90% of activity after incubated at 40 degrees C for 25 min. Finally, rt-LlL was used to substitute commercial Photinus pyralis luciferase in conventional pyrosequencing reagent to get thermostable pyrosequencing reagent. Comparing with conventional pyrosequencing reagent, the thermostable pyrosequencing reagent is more stable, and it's activity would not lose when incubated at 37 degrees C for 1 h. This study laid foundation of establishing reliable and stable pyrosequencing system which would be applied in Point-of-Care Testing.
Animals ; Enzyme Stability ; Escherichia coli ; genetics ; metabolism ; Fireflies ; enzymology ; Luciferases ; biosynthesis ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; Sequence Analysis, DNA ; methods

Pyruvate phosphate dikinase (PPDK; EC 2.7.9.1) is found in certain microorganisms and plants, and catalyzes the conversion of AMP, PPi and phosphoenolpyruvate (PEP) to ATP, Pi and pyruvate. Using the genomic DNA of Microbispora rosea subsp. aerata as the template, a DNA fragment encoding the gene PPDK was amplified by PCR and inserted into the expression vector pET28a(+), yielding pET28a (+)-PPDK. The E. coli BL21 (DE3) was transformed with the pET28a (+)-PPDK. After inducing with IPTG, the E. coli BL21 (DE3) [pET28a (+)-PPDK] expressed recombinant PPDK fused to an N-terminal sequence of 6-His Tag. The molecular weight of PPDK was estimated to be 101 kD by SDS-PAGE. The PPDK was purified by His * Bind Resin affinity chromatography and ultrafiltration using 10 kD cut-off membrane. The successful application of PPDK in pyrosequencing was also demonstrated.
Actinomyces ; enzymology ; Escherichia coli ; genetics ; metabolism ; Pyruvate, Orthophosphate Dikinase ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Recombination, Genetic ; Sequence Analysis

The in vivo assembly of ribosomal subunits is a highly complex process, with a tight coordination between protein assembly and rRNA maturation events, such as folding and processing of rRNA precursors, as well as modifications of selected bases. In the cell, a large number of factors are required to ensure the efficiency and fidelity of subunit production. Here we characterize the immature 30S subunits accumulated in a factor-null Escherichia coli strain (∆rsgA∆rbfA). The immature 30S subunits isolated with varying salt concentrations in the buffer system show interesting differences on both protein composition and structure. Specifically, intermediates derived under the two contrasting salt conditions (high and low) likely reflect two distinctive assembly stages, the relatively early and late stages of the 3' domain assembly, respectively. Detailed structural analysis demonstrates a mechanistic coupling between the maturation of the 5' end of the 17S rRNA and the assembly of the 30S head domain, and attributes a unique role of S5 in coordinating these two events. Furthermore, our structural results likely reveal the location of the unprocessed terminal sequences of the 17S rRNA, and suggest that the maturation events of the 17S rRNA could be employed as quality control mechanisms on subunit production and protein translation.
Cryoelectron Microscopy ; Escherichia coli ; metabolism ; Escherichia coli Proteins ; genetics ; metabolism ; GTP Phosphohydrolases ; genetics ; metabolism ; Mass Spectrometry ; Protein Structure, Secondary ; Protein Structure, Tertiary ; RNA, Ribosomal ; analysis ; metabolism ; Ribosomal Proteins ; chemistry ; genetics ; metabolism ; Ribosome Subunits, Small, Bacterial ; chemistry ; metabolism ; ultrastructure ; Salts ; chemistry

OBJECTIVETo recombine OspC gene from Borrelia burgdorferi PD91 of China and expressed it in E. coli for early diagnosis of Lyme disease.

METHODSThe OspC gene was amplified from the genome of Borrelia burgdorferi PD91 strain by polymerase chain reaction and recombined with plasmid PET-11D. The recombinant plasmid PET-11D-OspC was identified with PCR, restriction endonuclease analysis and sequencing. The antigenicity was verified with Western Blot.

RESULTSOspC gene was cloned correctly into vector PET-11D. The resultant sequence was definitely different from the published sequence. The recombinant OspC seemed to have had strong antigenicity.

CONCLUSIONThe findings laid basis for the studies on early diagnosis of Lyme disease.

Antigens, Bacterial ; Bacterial Outer Membrane Proteins ; genetics ; immunology ; Blotting, Western ; Borrelia burgdorferi Group ; immunology ; Escherichia coli ; genetics ; Humans ; Lyme Disease ; diagnosis ; Polymerase Chain Reaction ; Recombinant Proteins ; analysis ; immunology

We expressed recombinant single-stranded DNA-binding protein (r-SSBP) from Escherichia coli with the molecular weight of 24-kDa by using genetic engineering strategy, and demonstrated the single-stranded DNA (ssDNA)-binding activity of r-SSBP by electrophoretic mobility shift assay (EMSA). To further characterize r-SSBP, we studied the effects of r-SSBP on melting temperature (T(m)) of DNA. The results showed that r-SSBP could bind to ssDNA, and lower the T(m) of DNA, especially for single-base mismatched DNA. Therefore, r-SSBP significantly increased the T(m) difference between single-base mismatched DNA and perfect matched DNA. These results are very beneficial for single-nucleotide polymorphism detection. Moreover, we applied r-SSBP in high sensitive pyrosequencing system developed by our group. The results suggest that the r-SSBP decreased non-specific signals, corrected the proportion of signal peak height and improved the performance of pyrosequencing.
DNA-Binding Proteins ; biosynthesis ; genetics ; Diphosphates ; metabolism ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; Recombinant Proteins ; biosynthesis ; genetics ; Sequence Analysis, DNA ; methods