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Multiple sugar: phosphotransferase system permeases participate in catabolite modification of gene expression in Streptococcus mutans
Author(s) -
Zeng Lin,
Burne Robert A.
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06403.x
Subject(s) - biology , pep group translocation , catabolite repression , permease , streptococcus mutans , gene , phosphotransferase , sugar , microbiology and biotechnology , gene expression , biochemistry , genetics , transporter , bacteria , phosphoenolpyruvate carboxykinase , mutant
Summary Streptococcus mutans is particularly well adapted for high‐affinity, high‐capacity catabolism of multiple carbohydrate sources. S. mutans enzyme II (EII Lev ), a fructose/mannose permease encoded by the levDEFG genes, and fruA , which encodes a hydrolase that releases fructose from fructan polymers, are transcriptionally regulated by the LevQRST four‐component signal transduction system. Here, we demonstrate that: (i) levDEFGX are co‐transcribed and the levE/F intergenic region is required for optimal expression of levFGX ; (ii) D‐mannose is a potent inducer of the levD and fruA operons; (iii) CcpA regulates levD expression in a carbohydrate‐specific manner; (iv) deletion of the genes for the fructose/mannose‐EII enzymes of S. mutans ( manL , fruI and levD ) enhances levD expression; (v) repression of the LevQRST regulon by EII enzymes depends on the presence of their substrates and requires LevR, but not LevQST; and (vi) CcpA inhibits expression of the manL and fruI genes to indirectly control the LevQRST regulon. Further, the manL , ccpA , fruI/fruCD and levD gene products differentially exert control over the cellobiose and lactose operons. Collectively, the results reveal the existence of a global regulatory network in S. mutans that governs the utilization of non‐preferred carbohydrates in response to the availability and source of multiple preferred carbohydrates.