R. Marasco et al., A physical and functional analysis of the newly-identified bglGPT operon of Lactobacillus plantarum, FEMS MICROB, 186(2), 2000, pp. 269-273
A newly-identified bbl/GPT operon of Lactobacillus plantarum was isolated a
nd expressed in Escherichia coli. The sequence analysis of the cloned DNA f
ragment showed three open reading frames encoding (i) a 237-amino acid prot
ein (BglG), (ii) a 577-amino acid protein (BglP) and (iii) a 486-amino acid
protein (BglT). BglG, BglP and BglT were shown to be homologous to the Bgl
G family of transcriptional antiterminators, to permeases of the phosphoeno
lpyruvate-dependent phosphotransferase system and to beta-glucosidases, res
pectively. Complementation of E. coli mutant strains showed that BglP and B
glT are a permease and a beta-glucosidase active on the beta-glucosides, 5-
bromo-4-chloro-3-indolyl-beta-D-glucopyranoside and p-nitrophenyl-beta-D-gl
ucoside, respectively. BglG was also shown to promote expression of a bglG-
lacZ gene fusion in an E, coli bglG(-) background. A ribonucleic antitermin
ator sequence, the antiterminator-responsive cis-element and a 'catabolite
responsive element', were found downstream of the transcriptional start poi
nt. Transcription of the operon was repressed 10-fold in L. plantarum cells
grown on glucose as compared to ribose. (C) 2000 Federation of European Mi
crobiological Societies. Published by Elsevier Science B.V. All rights rese
rved.