Keeping signals straight in transcription regulation: specificity determinants for the interaction of a family of conserved bacterial RNA-protein couples.
Regulatory systems often evolve by duplication of ancestral systems and subsequent specialization of the components of the novel signal transduction systems. In the Gram-positive soil bacterium Bacillus subtilis, four homologous antitermination systems control the expression of genes involved in the metabolism of glucose, sucrose and beta-glucosides. Each of these systems is made up of a sensory sugar permease that does also act as phosphotransferase, an antitermination protein, and a RNA switch that is composed of two mutually exclusive structures, a RNA antiterminator (RAT) and a transcriptional terminator. We have studied the contributions of sugar specificity of the permeases, carbon catabolite repression, and protein-RAT recognition for the straightness of the signalling chains. We found that the beta-glucoside permease BglP does also have a minor activity in glucose transport. However, this activity is irrelevant under physiological conditions since carbon catabolite repression in the presence of glucose prevents the synthesis of the beta-glucoside permease. Reporter gene studies, in vitro RNA-protein interaction analyzes and northern blot transcript analyzes revealed that the interactions between the antiterminator proteins and their RNA targets are the major factor contributing to regulatory specificity. Both structural features in the RATs and individual bases are important specificity determinants. Our study revealed that the specificity of protein-RNA interactions, substrate specificity of the permeases as well as the general mechanism of carbon catabolite repression together allow to keep the signalling chains straight and to avoid excessive cross-talk between the systems.
Schilling
Oliver
O
Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University, Göttingen Germany.
Herzberg
Christina
C
Hertrich
Tina
T
Vörsmann
Hanna
H
Jessen
Dirk
D
Hübner
Sebastian
S
Titgemeyer
Fritz
F
Stülke
Jörg
J
D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D020029:Base Pairing; D001665:Binding Sites; D001692:Biological Transport; D002244:Carbon / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D009690:Nucleic Acid Conformation; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D012329:RNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D015398:Signal Transduction; D013379:Substrate Specificity; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
D001426:Bacterial Proteins; C115000:GlcT protein, Bacillus subtilis; C098955:LicT protein, Bacteria; D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; C076894:SacY protein, Bacillus subtilis; D014157:Transcription Factors; C064872:antiterminator proteins, Bacteria; D002244:Carbon; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C031629:phosphoenolpyruvate-glucose phosphotransferase; D005947:Glucose