Structure and Expression of the Lactococcus lactis Gene for Phospho- -galactosidase (lacG) in Escherichia coli and L. lactis

Vos, Willem M. de; Gasson, Mike

doi:10.1099/00221287-135-7-1833

Cited by 40 publications

(54 citation statements)

References 42 publications

(28 reference statements)

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“…They thus endow their hosts with many traits which offer a selective advantage to colonize specific biotopes. For example, the majority of dairy strains have adapted to growth in milk by acquiring plasmids that encode lactose catabolism (De Vos & Gasson, 1989), casein degradation (Kok, 1990), citrate utilization (Kempler & McKay, 1979) and oligopeptide transport (Yu et al, 1996). In addition, strains isolated from plant and animal environments, which contain a wide variety of cytotoxic compounds, have developed appropriate protection mechanisms (Putman et al, 2000), such as multidrug resistance, nisin resistance and heavy metal resistance (Dougherty et al, 1998;Liu et al, 1997; Perreten et al, 1997), and the genes for these mechanisms are often carried by plasmids.…”

mentioning

confidence: 99%

Sequence analysis of the mobilizable lactococcal plasmid pGdh442 encoding glutamate dehydrogenase activity

2007

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A novel plasmid named pGdh442 had previously been isolated from a plant Lactococcus lactis strain. This plasmid encodes two interesting properties with applications in the dairy industry: a glutamate dehydrogenase activity that stimulates amino acid conversion to aroma compounds, and cadmium/zinc resistance that can be used as a selectable marker. Moreover, this plasmid can be transferred naturally to other strains, but appears to be incompatible with certain other lactococcal plasmids. During this study, the complete sequence of pGdh442 (68 319 bp) was determined and analysed. This plasmid contains 67 ORFs that include 20 IS elements that may have mediated transfer events between L. lactis and other genera living in the same biotope, such as Streptococcus, Pediococcus and Lactobacillus. Even though it is a low-copy-number plasmid, it is relatively stable due to a theta replication mode and the presence of two genes involved in its maintenance system. However, pGdh442 is incompatible with pSK08-derived protease/lactose plasmids because both possess the same replication and partition system. pGdh442 is not self-transmissible, but can be naturally transmitted via mobilization by conjugative elements carried by the chromosome or by other plasmids, such as the 712-type sex factor, which is widely distributed in L. lactis. In addition to several genes already found on other L. lactis plasmids, such as the oligopeptide transport and utilization genes, pGdh442 also carries several genes not yet identified in L. lactis. Finally, it does not carry genes that would trigger concern over its presence in human food. INTRODUCTIONLactococcus lactis is a lactic acid bacterium (LAB) widely used as a starter culture for the production of various fermented dairy products. Although this bacterium is commonly found in milk, it is also naturally present on plants and on parts of the bodies of cows (Nomura et al., 2006;Salama et al., 1995;Teuber, 1995). Typically, Lactococcus strains possess an abundance of plasmid DNA. Many large L. lactis plasmids are self-transmissible or mobilizable by conjugative elements carried by the chromosome or plasmids of the host strain (Gasson et al., 1995). Through their natural transfer, these plasmids increase the probability of the gene moving between bacteria, and enable strains to acquire a wide variety of new genetic traits. They thus endow their hosts with many traits which offer a selective advantage to colonize specific biotopes. For example, the majority of dairy strains have adapted to growth in milk by acquiring plasmids that encode lactose catabolism (De Vos & Gasson, 1989), casein degradation (Kok, 1990), citrate utilization (Kempler & McKay, 1979) and oligopeptide transport (Yu et al., 1996). In addition, strains isolated from plant and animal environments, which contain a wide variety of cytotoxic compounds, have developed appropriate protection mechanisms (Putman et al., 2000), such as multidrug resistance, nisin resistance and heavy metal resistance (Dougherty et al., 1998;Liu et al.,...

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confidence: 99%

Sequence analysis of the mobilizable lactococcal plasmid pGdh442 encoding glutamate dehydrogenase activity

2007

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“…Genetic studies have shown that the lactose-specific phosphotransferase system enzymes are homologous and plasmid encoded in Lactococcus lactis (14)(15)(16)30) and Lactobacillus casei (1,2,38). In contrast, the homologous lac genes of Streptococcus thernophilus and Lactobacillus bulgaricus are chromosomally located and have been found to encode unique lactose permeases (28,37) and ,B-galactosidases that show high similarity to those of gram-negative bacteria (42,43).…”

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confidence: 99%

Leuconostoc lactis beta-galactosidase is encoded by two overlapping genes

et al. 1992

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A 16-kb BamHI fragment of the lactose plasmid pNZ63 from Leuconostoc lactis NZ6009 was cloned in Escherichia coli MC1061 by using pACYC184 and was found to express a functional j-galactosidase. Deletion and complementation analysis showed that the coding region for ,-galactosidase was located on a 5. Mutation and deletion analysis showed that lacL expression is essential for LacM production and that both the lacL and lacM genes are required for the production of a functional 1-galactosidase in E. coli. The deduced amino acid sequences of the LacL and LacM proteins showed considerable identity with the sequences of the N-and C-terminal parts, respectively, of ,-galactosidases from other lactic acid bacteria or E. coli. DNA and protein sequence alignments suggest that the L. lactis lacL and lacM genes have been generated by an internal deletion in an ancestral 13-galactosidase gene.Two systems for lactose transport and hydrolysis among bacteria are known. The first system has only been found in gram-positive bacteria and involves a phosphoenolpyruvatedependent phosphotransferase system, by which lactose is phosphorylated during transport and subsequently hydrolyzed by a phospho-,B-galactosidase (for reviews, see references 14 and 22). In the second, more widespread system, lactose is transported across the cellular membrane by a galactoside permease, and the unmodified internalized sugar is hydrolyzed by a 13-galactosidase. Most research has focused on the lactose permease (lacY) and ,-galactosidase (lacZ) genes from Escherichia coli (for reviews, see references 3, 24, and 25), and its lacZ gene has been developed into a useful tool in molecular genetics. Similar lac genes located on chromosomal or plasmid DNA have been found in other gram-negative bacteria (20), and in one instance a lac transposon (Tn951) has been reported (11).Recently, lac genes have been characterized in lactic acid bacteria that are used as starter cultures in dairy fermentations and therefore are highly specialized lactose utilizers. Genetic studies have shown that the lactose-specific phosphotransferase system enzymes are homologous and plasmid encoded in Lactococcus lactis (14)(15)(16)30) and Lactobacillus casei (1, 2, 38). In contrast, the homologous lac genes of Streptococcus thernophilus and Lactobacillus bulgaricus are chromosomally located and have been found to encode unique lactose permeases (28, 37) and ,B-galactosidases that show high similarity to those of gram-negative bacteria (42,43). A plasmid-encoded P-galactosidase in Lactobacillus casei ATCC 393 has been reported (10). In addition, we showed recently that Leuconostoc lactis NZ6009 also contains a lactose plasmid that codes for a P-galactosidase (13). gram-positive cocci that are used for industrial milk and wine fermentations. We recently started the genetic characterization of Leuconostoc spp. (13) and focused on the plasmidlocated lac genes in L. lactis NZ6009 (12). Here we describe the molecular characterization of a DNA fragment from the lactose plasmid pNZ63 that ...

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“…In L. lactis ssp. cremoris strain NCDO712, the structural genes for the lactose-specific PTS enzymes (LacEF) as well as those for phospho-13-galactosidase and the enzymes of the tagatose-6-phosphate pathway (LacABCD) are organized in a 7.8-kb lac operon: lacABCDFEGX (de Vos & Gasson, 1989;de Vos et al, 1990;van Rooijen et al, 1991; see Figure 1). An oppositely oriented gene immediately upstream of lacA, lacR, specifies a repressor protein .…”

Section: Lactose Metabolismmentioning

confidence: 99%

“…Both transcripts are initiated at a single lactoseinducible promoter upstream of lacA (van Rooijen et al, 1992). An inverted repeat between lacE and lacG could act as an intracistronic terminator for the 6-kb transcript with partial readthrough explaining the presence of the 8.5-kb mRNA (de Vos & Gasson, 1989;de Vos et al, 1990). lacR is transcribed as a monocistronic mRNA of 1.2 kb in the presence of glucose, while synthesis of this mRNA is repressed 5-fold during growth on lactose.…”

Section: Lactose Metabolismmentioning

confidence: 99%

Inducible gene expression and environmentally regulated genes in lactic acid bacteria

Kok

1996

Antonie van Leeuwenhoek

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Link to publication in University of Groningen/UMCG research database Citation for published version (APA): . Inducible gene expression and environmentally regulated genes in lactic acid bacteria. Antonie Van Leeuwenhoek: International Journal of General and Molecular Microbiology, 70(2-4), 129-145. https://doi.org/10.1007/BF00395930 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. SummaryRelatively recently, a number of genes and operons have been identified in lactic acid bacteria that are inducible and respond to environmental factors. Some of these genes/operons had been isolated and analysed because of their importance in the fermentation industry and, consequently, their transcription was studied and found to be regulatable. Examples are the lactose operon, the operon for nisin production, and genes in the proteolytic pathway ofLactococcus lactis, as well as xylose metabolism in Lactobacilluspentosus. Some other operons were specifically targetted with the aim to compare their mode of regulation with known regulatory mechanisms in other well-studied bacteria. These studies, dealing with the biosynthesis of histidine, tryptophan, and of the branched chain amino acids in L. lactis, have given new insights in gene regulation and in the occurrence of auxotrophy in these bacteria. Also, nucleotide sequence analyses of a number of lactococcal bacteriophages was recently initiated to, among other things, specifically learn more about regulation of the phage life cycle. Yet another approach in the analysis of regulated genes is the 'random' selection of genetic elements that respond to environmental stimuli and the first of such sequences from lactic acid bacteria have been identified and characterized. The potential of these regulatory elements in fundamental research and practical (industrial) applications will be discussed.

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Structure and Expression of the Lactococcus lactis Gene for Phospho- -galactosidase (lacG) in Escherichia coli and L. lactis

Cited by 40 publications

References 42 publications

Sequence analysis of the mobilizable lactococcal plasmid pGdh442 encoding glutamate dehydrogenase activity

Sequence analysis of the mobilizable lactococcal plasmid pGdh442 encoding glutamate dehydrogenase activity

Leuconostoc lactis beta-galactosidase is encoded by two overlapping genes

Inducible gene expression and environmentally regulated genes in lactic acid bacteria

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