Bacteria are often infected by large numbers of phages, and host bacteria have evolved diverse molecular strategies in the race with phages, with abortive infection (Abi) being one of them. The toxin-antitoxin system (TA) is expressed in response to bacterial stress, mediating hypometabolism and even dormancy, as well as directly reducing the formation of offspring phages. In addition, some of the toxins' sequences and structures are highly homologous to Cas, and phages even encode antitoxin analogs to block the activity of the corresponding toxins. This suggests that the failure of phage infection due to bacterial death in abortive infections is highly compatible with TA function, whereas TA may be one of the main resistance and defense forces for phage infestation of the host. This review summarized the TA systems involved in phage abortive infections based on classification and function. Moreover, TA systems with abortive functions and future use in antibiotic development and disease treatment were predicted. This will facilitate the understanding of bacterial-phage interactions as well as phage therapy and related synthetic biology research.
Anti-Bacterial Agents ; Antitoxins/chemistry* ; Bacteria/genetics* ; Bacterial Proteins/chemistry* ; Bacterial Toxins/genetics* ; Bacteriophages/genetics* ; Toxin-Antitoxin Systems/genetics*

OBJECTIVECorynebacterium crenatum MT, a mutant from C. crenatum AS 1.542 with a lethal argR gene, exhibits high arginine production. To confirm the effect of ArgR on arginine biosynthesis in C. crenatum, an intact argR gene from wild-type AS 1.542 was introduced into C. crenatum MT, resulting in C. crenatum MT. sp, and the changes of transcriptional levels of the arginine biosynthetic genes and arginine production were compared between the mutant strain and the recombinant strain.

METHODSQuantitative real-time polymerase chain reaction was employed to analyze the changes of the related genes at the transcriptional level, electrophoretic mobility shift assays were used to determine ArgR binding with the argCJBDF, argGH, and carAB promoter regions, and arginine production was determined with an automated amino acid analyzer.

RESULTSArginine production assays showed a 69.9% reduction in arginine from 9.01 ± 0.22 mg/mL in C. crenatum MT to 2.71 ± 0.13 mg/mL (P<0.05) in C. crenatum MT. sp. The argC, argB, argD, argF, argJ, argG, and carA genes were down-regulated significantly in C. crenatum MT. sp compared with those in its parental C. crenatum MT strain. The electrophoretic mobility shift assays showed that the promoter regions were directly bound to the ArgR protein.

CONCLUSIONThe arginine biosynthetic genes in C. crenatum are clearly controlled by the negative regulator ArgR, and intact ArgR in C. crenatum MT results in a significant descrease in arginine production.

Arginine ; biosynthesis ; Bacterial Proteins ; chemistry ; genetics ; metabolism ; Corynebacterium ; genetics ; metabolism ; Gene Expression Regulation, Bacterial ; Repressor Proteins ; chemistry ; genetics ; metabolism

Bacterial Proteins ; chemistry ; genetics ; metabolism ; DNA, Bacterial ; chemistry ; genetics ; metabolism ; Gene Expression Regulation, Bacterial ; physiology ; Glutathione ; metabolism ; Listeria monocytogenes ; chemistry ; genetics ; metabolism ; Peptide Termination Factors ; chemistry ; genetics ; metabolism

OBJECTIVETo determine the sequence of the active peptide derived from recombinant hemagglutinin (rHA-2) of Porphyromonas gingivalis (Pg).

METHODSThe HA-2 gene from PgATCC33277 was cloned, expressed in Escherichia coli (Ec) BL21 (DE3), and purified. The purified recombinant protein was evaluated for its ability to bind hemin-linked agarose. The active peptide was subjected to endoproteinase-mediated sequence analysis.

RESULTSThe protein expressed in Ec BL21 (DE3) was identified as PgHA-2 by plasmid sequence analysis, Western blotting, and mass spectrometry. The recombinant protein was confirmed functional by its ability to bind hemin. The sequence of the active peptide of rHA-2 was determined to be DHYAVMISKTGTNAG.

CONCLUSIONSThe availability of sequence of the active peptide of rHA-2 provides a foundation for the development of immunoprophylactic and therapeutic agents against this human pathogen.

Bacterial Proteins ; chemistry ; genetics ; Hemagglutinins ; chemistry ; genetics ; Porphyromonas gingivalis ; genetics ; Sequence Analysis, Protein

Bacterial Outer Membrane Proteins ; chemistry ; genetics ; physiology ; Bacteriophages ; chemistry ; Humans ; Receptors, Virus ; chemistry ; Vibrio cholerae ; virology

As the dominant antigens, early secreted antigenic target 6 (ESAT6, E6) and culture filtrate protein 10 (CFP10, C10) had once been the focus of tuberculosis (TB) vaccine due to their capability of inducing strong cell immune response in the host. They are also endowed with promising future of prevention against and diagnosis of TB. In this review, we systematically introduce recent research progress of E6 and C10, especially in structure-function, biological characteristics, protein expression and secretion, host immunity and vaccine development, and the prospects of their application are also discussed.
Antigens, Bacterial ; chemistry ; genetics ; immunology ; Bacterial Proteins ; chemistry ; genetics ; immunology ; Humans ; Immunodominant Epitopes ; immunology ; Molecular Biology ; Peptide Fragments ; chemistry ; genetics ; immunology ; Tuberculosis Vaccines ; genetics ; immunology ; Vaccines, DNA ; immunology

Genomic DNA sequence analysis of phytochrome like photoreceptors in a number of bacteria revealed several open reading frames (ORFs) encoding proteins with amino acid sequences homologous to plant phytochromes. The phytochrome like photoreceptors, collectively called bacteriophytochromes, contain an N-terminal domain homologous to the chromophore-binding domain (CBD) of higher plants and a C-terminal domain of histidine kinase domain( HKD). Due to their simple structure, bacteriophytochromes broaden the view of phytochrome evolution and provide us with a simple model to investigate phytochrome-mediated light signal in higher plants. In this report, the bacteriophytochromes from Synechocystis sp. PCC6803 were investigated. The gene cph1 and its fragment cph1 (C-435) were isolated from the Synechocystis sp. PCC6803 genomic DNA by polymerase chain reaction(PCR) using specific primers. Then, the genes were cloned with the vector pBluescript, yielding plasmids pBlu-cphl and pBlu-cph1 ( C-435), before they are subcloned with the vector pET30, using the EcoRV and Xho I restriction sites. pBlu-cph1, pBlu-cph1 (N-435) were cleaved with Sma I and Xho I, and the released genes were ligated to the pET30a fragment. The E. coli [strain BL21 (DE3)] cells containing recombinant pET30a were grown in medium RB at 20 degrees C, and harvested 6 h later after induction with isopropyl thio-beta-D-galactoside (IPTG). Then, reconstitution systems were employed to study the characteristics of the genes. In the reconstitution system, autoassembly of aprotein of phytochrome with PCB was investigated. The chromophore addition was an autocatalytic process. Reconstitution products were red/infrared (R/FR) photochromic, which was similar to that of the phytoehrome in higher plants. How ever, the spectral change ratios (deltaAmax/deltaAmin) of the two fragments differed from each other. It was also shown that PCB was covalently bound to apo-protein via Zn2+ fluoresc ence SDS-PAGE. After irradiation by light of 700 nm, the maximum absorption spectrum o f holo-Cphl was 650nm. The absorption of it after denaturatior in the dark with ur ea in the presence of hydrochloric acid (pH = 2) was 660nm, which was similar with th at of cis-PCB. In addition, after irradiation by light of 650nm, the maximum absorption spectrum of holo-Cph1 was 700nm. The absorption of it after denaturation in the dark with urea in the presence of hydrochloric acid (pH = 2) was 600nm, which was similar with that of trans-PCB. The result showed that the photochromism of phytochrome resulted from the isomerizaation of chromophore (PCB in this report). The reconstitution of Cph1 (C-435) under the same condition supported the conclusion. Fluorescence emission spectrum of the products suggested that bacteriophytochrom e structure with cis-PCB was more stable than that with trans-PCB. The new reconstitution system in this report sets a base for the application of phytochrome as photochromic biomaterials in biosensors. In addition, phytochrome shows great potential in food, cosmetic and biological engineering, etc.
Bacterial Proteins ; biosynthesis ; chemistry ; genetics ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Gene Expression Regulation, Bacterial ; radiation effects ; Genetic Vectors ; Photochemistry ; Phytochrome ; biosynthesis ; chemistry ; genetics ; Protein Kinases ; biosynthesis ; chemistry ; genetics ; Recombinant Proteins ; biosynthesis ; chemistry ; genetics ; Synechocystis ; chemistry

Streptomyces coelicolor is the model species among streptomycetes. Until now, proteomic analyses of S. coelicolor have been conducted using two-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry method, few integral membrane proteins were identified due to the hydrophobic and low-abundance nature of these proteins. In this work, 154 possible inner membrane proteins from S. coelicolor were identified using high pH-proteinase K sample preparation method and multidimensional protein identification technology, among them 44 are integral membrane proteins containing at least one transmembrane domain, most peptides and their corresponding proteins were identified experimentally for the first time.
Bacterial Proteins ; analysis ; Cell Membrane ; chemistry ; Genome, Bacterial ; genetics ; Mass Spectrometry ; methods ; Membrane Proteins ; analysis ; Proteome ; analysis ; genetics ; Streptomyces coelicolor ; chemistry ; genetics

Bacterial Outer Membrane Proteins ; chemistry ; genetics ; metabolism ; Escherichia coli Proteins ; chemistry ; genetics ; metabolism ; Glutamic Acid ; genetics ; metabolism ; Histidine ; genetics ; Hydrogen-Ion Concentration ; Ion Channel Gating ; genetics ; Lipid Bilayers ; metabolism ; Mutant Proteins ; chemistry ; genetics ; metabolism ; Mutation ; Porins ; chemistry ; genetics ; metabolism

Halohydrin dehalogenase is of great significance for biodegradation of the chlorinated pollutants, and also serves as an important biocatalyst in the synthesis of chiral pharmaceutical intermediates. A putative halohydrin dehalogenase (HheTM) gene from Tistrella mobilis KA081020-065 was cloned and over-expressed in Escherichia coli BL21 (DE3). The recombinant enzyme was purified by Ni-NTA column and characterized. Gel filtration and SDS-PAGE analysis showed that the native form of HheTM was a tetramer. It exhibited the highest activity at 50 degrees C. The nature and pH of the buffer had a great effect on its activity. The enzyme maintained high stability under the alkaline conditions and below 30 degrees C. HheTM catalyzed the transformation of ethyl(S)-4-chloro-3-hydroxybutyrate in the presence of cyanide, to give ethyl (R)-4-cyano-3-hydroxybutyrate, a key intermediate for the synthesis of atorvastatin.
3-Hydroxybutyric Acid ; chemistry ; Bacterial Proteins ; genetics ; metabolism ; Cloning, Molecular ; Escherichia coli ; Hydrolases ; genetics ; metabolism ; Hydroxybutyrates ; chemistry ; Recombinant Proteins ; genetics ; metabolism ; Rhodospirillaceae ; enzymology ; genetics