Specific interaction of the RNA-binding domain of the bacillus subtilis transcriptional antiterminator GlcT with its RNA target, RAT.

Expression of the Bacillus subtilis ptsGHI operon is controlled by transcriptional antitermination mediated by the antiterminator protein GlcT. The antiterminator is inactivated in the absence of glucose, presumably by phosphorylation. A conditional terminator in the ptsG mRNA leader region has been identified. Mutations in this terminator resulted in constitutive expression of the operon. The terminator is overlapped by an inverted repeat (called ribonucleic-antiterminator, RAT) which is thought to form a stem-loop structure upon binding of the antiterminator protein GlcT. The N-terminal 60 amino acid residues of GlcT are able to bind to the RAT and prevent transcriptional termination in vivo. Sequence-specific interaction between the RNA-binding domain and the RAT was demonstrated by surface plasmon resonance analysis. Mutations affecting the RNA-binding domain were isolated and will be discussed with respect to their consequences for dimerization and RNA binding.