Control of expression of the arginine deiminase operon of Streptococcus gordonii by CcpA and Flp

Abstract

In Streptococcus gordonii DL1, inactivation of the ccpA gene and a gene encoding an Fnr-like protein (Flp) demonstrated that CcpA was essential for carbohydrate catabolite repression and that Flp was required for optimal expression and anaerobic induction of the arginine deiminase system.

FIG. 1.

Alignment of the deduced amino acid sequences of Flp and representative members of the Crp/Fnr family. The identical residues are indicated with boldface characters and gray-shaded boxes; the conserved residues Arg-212 and Glu-213 (potentially involved in protein-DNA interactions) are indicated by asterisks. This alignment was performed with ClustalW alignment and MacVector software.

FIG. 2.

Nucleotide sequence and relevant features of the 5′ region of arcA. The start codon of arcA and the stop codon of flp are indicated with solid arrows. The promoter that directs the transcription of arcA (7) is indicated with boldface characters. The two inverted repeats with the potential to function as terminators, SL1 (positions −192 to −175) and SL2 (positions −166 to −149), are between the flp and arcA genes and are indicated by boldface characters and dotted arrows. TIS, transcription initiation site.