The N-terminus is unstructured, but not dynamically disordered, in the complex between HK022 Nun protein and lambda-phage BoxB RNA hairpin.
The Nun protein of lambdoid phage HK022 excludes lambda-phage superinfection by blocking expression of genes downstream from the lambda nut sequences. Heteronuclear NMR studies have been performed on a Nun peptide comprising residues 1-49 bound to the nutR BoxB RNA. The pattern of (13)C chemical shifts indicates that the arginine-rich motif of Nun forms an induced alpha-helix, consisting of residues 23-43, when bound to BoxB RNA, consistent with the structure of a shorter (residues 22-44) Nun peptide/BoxB RNA complex [Faber, C., Schärpf, M., Becker, T., Sticht, H. and Rösch (2001) J. Biol. Chem. 276, 32064-32070]. The N-terminal extension, residues 1-22, does not show chemical shifts or nuclear Overhauser effects characteristic of stable secondary structure. Nonetheless, (15)N relaxation measurements indicate that this region is not completely disordered, as expected for a random coil peptide. Restriction of conformation flexibility in the N-terminal extension of Nun may be important for binding to other target molecules involved in transcription termination.
Stuart
Ashley C
AC
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
Gottesman
Max E
ME
Palmer
Arthur G
AG
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011487:Protein Conformation; D016337:RNA, Catalytic / Q000737:chemistry* / Q000378:metabolism*; D012367:RNA, Viral / Q000737:chemistry* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism*
C073501:Nun protein, Enterobacteria phage HK022; D016337:RNA, Catalytic; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D014764:Viral Proteins; C418481:hairpin ribozyme