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1
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Overproduction and purification of the CcpA protein from Lactococcus lactis.

100%
Kowalczyk M., Bardowski J.
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2003
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vol. 50
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issue 2
455-459
EN
In this work we present cloning and overexpression of lactococcal CcpA protein in Escherichia coli Xl1blue strain as a fusion with 6×His tag. A high yield of the CcpA protein was obtained when the cells were cultured in liquid medium LB with 100 Μg/ml ampicillin at 37°C and subsequently for 4 h after induction by IPTG. The procedure let us obtain 5 mg of homogenous CcpA protein. Glutaraldehyde crosslinking analysis indicated the formation of dimer or tetramer forms of the CcpA protein.
2
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In vitro DNA binding of purified CcpA protein from Lactococcus lactis IL1403

81%
Kowalczyk M., Borcz B., Płochocka D., Bardowski J.
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2007
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vol. 54
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issue 1
71-78
EN
During this study His-tagged CcpA protein purified under native conditions to obtain a biologically active protein was used for molecular analysis of CcpA-dependent regulation. Using electrophoretic mobility shift assays it was demonstrated that CcpA of L. lactis can bind DNA in the absence of the HPr-Ser-P corepressor and exhibits DNA-binding affinity for nucleotide sequences lacking cre sites. However, purified HPr-Ser-P protein from Bacillus subtilis was shown to slightly increase the DNA-binding capacity of the CcpA protein. It was also observed that CcpA bound to the cre box forms an apparently more stable complex than that resulting from unspecific binding. Competition gel retardation assay performed on DNA sequences from two PEP:PTS regions demonstrated that the ybhE, bglS, rheB, yebE, ptcB and yecA genes situated in these regions are most probably directly regulated by CcpA.
3
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Biodiversity of Lactococcus lactis bacteriophages in Polish dairy environment

81%
Szczepańska A. K., Hejnowicz M. S., Kołakowski P., Bardowski J.
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2007
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vol. 54
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issue 1
151-158
EN
We present here the results of an exploration of the bacteriophage content of dairy wheys collected from milk plants localized in various regions of Poland. Thirty-three whey samples from 17 regions were analyzed and found to contain phages active against L. lactis strains. High phage titer in all whey samples suggested phage-induced lysis to be the main cause of fermentation failures. In total, over 220 isolated phages were examined for their restriction patterns, genome sizes, genetic groups of DNA homology, and host ranges. Based on DNA digestions the identified phages were classified into 34 distinct DNA restriction groups. Phage genome sizes were estimated at 14-35 kb. Multiplex PCR analysis established that the studied phages belong to two out of the three main lactococcal phage types - c2 and 936, while P335-type phages were not detected. Yet, analyses of bacterial starter strains revealed that the majority of them are lysogenic and carry prophages of P335-type in their chromosome. Phage geographical distribution and host range are additionally discussed.
4
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Lactococcus lactis IBB477 presenting adhesive and muco-adhesive properties as a candidate carrier strain for oral vaccination against influenza virus

71%
Radziwill-Bienkowska J., Żochowska D., Bardowski J., Mercier-Bonin M., Kowalczyk M.
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2014
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vol. 61
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issue 3
603-607
EN
In the gastrointestinal tract (GIT), adhesion is a prerequisite for bacterial colonization. Lactococci can be used in functional food (probiotics) and health-related applications (mucosal vaccines, therapeutic drug delivery), both potentially involving adhesive properties. A candidate lactic acid bacterium for influenza antigen delivery through the GIT should display the ability to adhere. The present work probes the interactions between Lactococcus lactis and mucins using pig gastric mucin (PGM) as a model. Two strains were used for the optimization of the screening method for adhesion: L. lactis subsp. cremoris IBB477 persistent in the GIT of germ-free rats, and the low-adhering control strain MG1820. High adhesion to bare and mucin-coated polystyrene of IBB477 in comparison with MG1820 was observed. We searched for genetic determinants potentially involved in the adhesion/muco-adhesion of IBB477, identifying two such genes: prtP and a gene coding for a protein with MUB and MucBP domains. Based on its persistence in the GIT and adhesive properties, L. lactis IBB477 is a candidate carrier strain for expression of influenza haemagglutinin (HA) protein for induction of mucosal immune response.
5
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Expression of avian influenza haemagglutinin (H5) and chicken interleukin 2 (chIL-2) under control of the ptcB promoter in Lactococcus lactis

52%
Szatraj K., Szczepankowska A., Sączyńska V., Florys K., Gromadzka B., Łepek K., Płucienniczak G., Szewczyk B., Zagórski-Ostoja W., Bardowski J.
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2014
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vol. 61
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issue 3
609-614
EN
Gram-positive and nonpathogenic lactic acid bacteria (LAB) are considered to be promising candidates for the development of new, safe systems of heterologous protein expression. Recombinant LAB has been shown to induce specific local and systemic immune response against selected pathogens, and could be a good alternative to classical attenuated carriers. The main goal of our study was to express the avian influenza haemagglutinin (H5) and chicken interleukin 2 (chIL-2) in Lactococcus lactis. Results of this study were anticipated to lead to construction of lactococcal strain(s) with potential vaccine properties against the avian influenza A (H5N1) virus. Expression of the cloned H5 gene, its His-tagged variant and chIL-2 gene, under the control of the ptcB gene promoter was attested by RT-PCR on transcriptional level and Western or dot blot analysis on translational level, demonstrating that system can be an attractive solution for production of heterologous proteins. The results of the preliminary animal trial conducted in mice are a promising step toward development of a vaccine against avian bird flu using Lactococcus lactis cells as antigen carriers.
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