Mutational analysis and chemical modification of Cys24 of lactococcin B, a bacteriocin produced by Lactococcus lactis
Article Abstract:
Mutants of lactococcin B were generated by replacing the cysteine residue (Cys24) with other possible amino acids. Mutants in which Cys24 was replaced by positively charged amino acids lost bacteriocin activity. On the other hand, treatment of wild-type bacteriocins with mercuric chloride resulted in their inactivation. Analysis of the effects of various lactococcin B derivatives on the membrane potential of energized cells of Lactococcus lactis IL1403 indicated dissipation of the membrane potential. These results suggest that the introduction of a positive charge to position 24 of Cys rather than oxidation was responsible for the inactivation of lactococcin B.
Publication Name: Microbiology
Subject: Biological sciences
ISSN: 1350-0872
Year: 1996
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The S-layer gene of Lactobacillus helveticus CNRZ 892: Cloning, sequence and heterologous expression
Article Abstract:
Surface layers (S-layers), consisting of protein monomers arranged in crystalline arrays have been described on Lactobacillus cell walls. Freeze-drying is thought to induce the detachment of S-layer monomers from the Lactobacillus acidophilus cell wall, although structural damaged is not linked to loss of cell viability. The cloning and nucleotide sequence of the gene encoding the S-layer protein of L. helviticus CNRZ 892, is presented, along with its expression in Lactococcus lactis, the Gram-positive heterologous host.
Publication Name: Microbiology
Subject: Biological sciences
ISSN: 1350-0872
Year: 1998
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Clustered organization and transcriptional analysis of a family of five csp genes of Lactococcus lactis MG1463
Article Abstract:
Lactococcus lactis MG1363 genes encoding cold shock proteins cspA, cspB, cspC, cspD and cspE have been cloned and sequenced. CspA-D were located in tandem repeats, encoding small proteins with high mutual sequence identities. Single transcripts of around 300 nucleotides for each csp gene were revealed and cspA-D mRNA levels increased on cold shock. CspE mRNA levels were not increased.
Publication Name: Microbiology
Subject: Biological sciences
ISSN: 1350-0872
Year: 1998
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