title: The sequence of sites recognised by a member of the RNase E/G family can control the maximal rate of cleavage, while a 5'-monophosphorylated end appears to function cooperatively in mediating RNA binding.
abstract: Members of the RNase E/G family are multimeric, 5'-end-sensing, single-strand-specific endoribonucleases that are found in chloroplasts as well as bacteria, and have central roles in RNA processing and degradation. A well-studied member of this family is Escherichia coli RNase G. Recently, we have shown that the interaction of this enzyme with a 5'-monophosphorylated end can enhance substrate binding in vitro and the decay of mRNA in vivo. We show here that a single-stranded site despite not being sufficient for rapid cleavage makes a substantial contribution to the binding of RNase G. Moreover, we find that the sequence of a site bound by RNase G can moderate the maximal rate by at least an order of magnitude. This supports a model for the RNase E/G family in which a single-stranded segment(s) can cooperate in the binding of enzyme that subsequently cleaves preferentially at another site. We also provide evidence that in order to promote cleavage a 5'-monophosphorylated end needs to be linked physically to a single-stranded site, indicating that it functions cooperatively. Our results are discussed in terms of recent X-ray crystal structures and models for the initiation of bacterial mRNA degradation.
authors: Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors: Stefanie Simone
authors: SS
authors: Jourdan
authors: Louise
authors: L
authors: Kime
authors: Kenneth John
authors: KJ
authors: McDowall
mesh_terms: D001483:Base Sequence; D004722:Endoribonucleases / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D009711:Nucleotides / Q000737:chemistry / Q000378:metabolism; D020871:RNA Stability; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D009711:Nucleotides; D012329:RNA, Bacterial; D012333:RNA, Messenger; D004722:Endoribonucleases; C081905:rng protein, E coli; C022537:ribonuclease E