Characterization of a lactose-responsive promoter of ATP-binding cassette (ABC) transporter gene from Lactobacillus acidophilus 05–172

Abstract

A novel lactose-responsive promoter of the ATP binding cassette (ABC) transporter gene Lba1680 of Lactobacillus acidophilus strain 05–172 isolated from a traditionally fermented dairy product koumiss was characterized. In L. acidophilus 05–172, expression of Lba1680 was induced by lactose, with lactose-induced transcription of Lba1680 being 6.1-fold higher than that induced by glucose. This is in contrast to L. acidophilus NCFM, a strain isolated from human feces, in which expression of Lba1680 and Lba1679 is induced by glucose. Both gene expression and enzyme activity assays in Lactobacillus paracasei transformed with a vector containing the inducible Lba1680 promoter (PLba1680) of strain 05–172 and a heme-dependent catalase gene as reporter confirmed that PLba1680 is specifically induced by lactose. Its regulatory expression could not be repressed by glucose, and was independent of cAMP receptor protein. This lactose-responsive promoter might be used in the expression of functional genes in L. paracasei incorporated into a lactose-rich environment, such as dairy products.

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