title: Modulating TRAP-mediated transcription termination by AT during transcription of the leader region of the Bacillus subtilis trp operon.
abstract: An 11-subunit protein called trp RNA binding Attenuation Protein (TRAP) controls attenuation of the tryptophan biosynthetic (trpEDCFBA) operon in Bacillus subtilis. Tryptophan-activated TRAP binds to 11 (G/U)AG repeats in the 5' leader region of trp mRNAs, and downregulates expression of the operon by promoting transcription termination prior to the structural genes. Anti-TRAP (AT) is an antagonist that binds to tryptophan-activated TRAP and prevents TRAP from binding to RNA, thereby upregulating expression of the trp genes. AT forms trimers, and multiple trimers bind to a TRAP 11mer. It is not known how many trimers must bind to TRAP in order to interfere with RNA binding. Studies of isolated TRAP and AT showed that AT can prevent TRAP from binding to the trp leader RNA but cannot dissociate a pre-formed TRAP-RNA complex. Here, we show that AT can prevent TRAP-mediated termination of transcription by inducing dissociation of TRAP from the nascent RNA when it has bound to fewer than all 11 (G/U)AG repeats. The 5'-most region of the TRAP binding site in the nascent transcript is most susceptible to dissociation from TRAP. We also show that one AT trimer bound to TRAP 11mer reduces the affinity of TRAP for RNA and eliminates TRAP-mediated transcription termination in vitro.
authors.affiliation: Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
authors.forename: Shraddha
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA gollnick@buffalo.edu.
authors.forename: Paul
authors.initials: P
authors.lastname: Gollnick
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D015964:Gene Expression Regulation, Bacterial; D008958:Models, Molecular; D009876:Operon; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D016601:RNA-Binding Proteins / Q000737:chemistry*; D012091:Repetitive Sequences, Nucleic Acid; D014157:Transcription Factors / Q000737:chemistry*; D061806:Transcription Termination, Genetic
chemical_list: D001426:Bacterial Proteins; C079092:MtrB protein, Bacteria; D021122:Protein Subunits; D012329:RNA, Bacterial; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C435924:yczA protein, Bacillus subtilis