The nucleotide sequences of the Lactobacillus helveticus lactose utilization genes were determined, and these genes were located and oriented relative to one another. The lacLM genes (encoding the β-galactosidase protein) were in a divergent orientation compared to lacR (regulatory gene) and lacS (lactose transporter). Downstream from lacM was an open reading frame (galE) encoding a UDP-galactose 4 epimerase, and the open reading frame had the same orientation as lacM. The lacR gene was separated from the downstream lacS gene by 2.0 kb of DNA containing several open reading frames that were derived from fragmentation of another permease gene (lacS′). Northern blot analysis revealed that lacL, lacM and galE made up an operon that was transcribed in the presence of lactose from an upstream lacL promoter. The inducible genes lacL and lacM were regulated at the transcriptional level by the LacR repressor. In the presence of glucose and galactose galE was transcribed from its promoter, suggesting that the corresponding enzyme can be expressed constitutively. Lactose transport was inducible by addition of lactose to the growth medium.

Fortina, M., Ricci, G., Mora, D., Guglielmetti, S., Manachini, P. (2003). Unusual Organization for Lactose and Galactose Gene Clusters in Lactobacillus helveticus. APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 69(6), 3238-3243 [10.1128/AEM.69.6.3238-3243.2003].

Unusual Organization for Lactose and Galactose Gene Clusters in Lactobacillus helveticus

Guglielmetti, S
Penultimo
;
2003

Abstract

The nucleotide sequences of the Lactobacillus helveticus lactose utilization genes were determined, and these genes were located and oriented relative to one another. The lacLM genes (encoding the β-galactosidase protein) were in a divergent orientation compared to lacR (regulatory gene) and lacS (lactose transporter). Downstream from lacM was an open reading frame (galE) encoding a UDP-galactose 4 epimerase, and the open reading frame had the same orientation as lacM. The lacR gene was separated from the downstream lacS gene by 2.0 kb of DNA containing several open reading frames that were derived from fragmentation of another permease gene (lacS′). Northern blot analysis revealed that lacL, lacM and galE made up an operon that was transcribed in the presence of lactose from an upstream lacL promoter. The inducible genes lacL and lacM were regulated at the transcriptional level by the LacR repressor. In the presence of glucose and galactose galE was transcribed from its promoter, suggesting that the corresponding enzyme can be expressed constitutively. Lactose transport was inducible by addition of lactose to the growth medium.
Articolo in rivista - Articolo scientifico
lactose operon; galactose operon; lactobacillus helveticus
English
2003
69
6
3238
3243
reserved
Fortina, M., Ricci, G., Mora, D., Guglielmetti, S., Manachini, P. (2003). Unusual Organization for Lactose and Galactose Gene Clusters in Lactobacillus helveticus. APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 69(6), 3238-3243 [10.1128/AEM.69.6.3238-3243.2003].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/458462
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