Crystal structure and RNA binding of the Tex protein from Pseudomonas aeruginosa.
Tex is a highly conserved bacterial protein that likely functions in a variety of transcriptional processes. Here, we describe two crystal structures of the 86-kDa Tex protein from Pseudomonas aeruginosa at 2.3 and 2.5 A resolution, respectively. These structures reveal a relatively flat and elongated protein, with several potential nucleic acid binding motifs clustered at one end, including an S1 domain near the C-terminus that displays considerable structural flexibility. Tex binds nucleic acids, with a preference for single-stranded RNA, and the Tex S1 domain is required for this binding activity. Point mutants further demonstrate that the primary nucleic acid binding site corresponds to a surface of the S1 domain. Sequence alignment and modeling indicate that the eukaryotic Spt6 transcription factor adopts a similar core structure. Structural analysis further suggests that the RNA polymerase and nucleosome interacting regions of Spt6 flank opposite sides of the Tex-like scaffold. Therefore, the Tex structure may represent a conserved scaffold that binds single-stranded RNA to regulate transcription in both eukaryotic and prokaryotic organisms.
Johnson
Sean J
SJ
Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA.
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Devin
D
Robinson
Howard
H
Vallet-Gely
Isabelle
I
Dove
Simon L
SL
Hill
Christopher P
CP
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D018360:Crystallography, X-Ray / Q000379:methods; D024202:Electrophoretic Mobility Shift Assay; D008958:Models, Molecular; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D012329:RNA, Bacterial / Q000378:metabolism*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D012329:RNA, Bacterial