title: Noncoding RNAs binding to the nucleoid protein HU in Escherichia coli.
abstract: Some unidentified RNA molecules, together with the nucleoid protein HU, were suggested to be involved in the nucleoid structure of Escherichia coli. HU is a conserved protein known for its role in binding to DNA and maintaining negative supercoils in the latter. HU also binds to a few RNAs, but the full spectrum of its binding targets in the cell is not known. To understand any interaction of HU with RNA in the nucleoid structure, we immunoprecipitated potential HU-RNA complexes from cells and examined bound RNAs by hybridization to whole-genome tiling arrays. We identified associations between HU and 10 new intragenic and intergenic noncoding RNAs (ncRNAs), 2 of which are homologous to the annotated bacterial interspersed mosaic elements (BIMEs) and boxC DNA repeat elements. We confirmed direct binding of HU to BIME RNA in vitro. We also studied the nucleoid shape of HU and two of the ncRNA mutants (nc1 and nc5) by transmission electron microscopy and showed that both HU and the two ncRNAs play a role in nucleoid morphology. We propose that at least two of the ncRNA species complex with HU and help the formation or maintenance of the architecture of the E. coli chromosome. We also observed binding of HU with rRNA and tRNA segments, a few small RNAs, and a distinct small set of mRNAs, although the significance, if any, of these associations is not known.
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Mirjana
authors.initials: M
authors.lastname: Macvanin
authors.forename: Rotem
authors.initials: R
authors.lastname: Edgar
authors.forename: Feng
authors.initials: F
authors.lastname: Cui
authors.forename: Andrei
authors.initials: A
authors.lastname: Trostel
authors.forename: Victor
authors.initials: V
authors.lastname: Zhurkin
authors.forename: Sankar
authors.initials: S
authors.lastname: Adhya
mesh_terms: D001483:Base Sequence; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D056656:Lab-On-A-Chip Devices; D040081:Protein Array Analysis; D011485:Protein Binding; D059370:RNA Folding; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D022661:RNA, Untranslated / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D022661:RNA, Untranslated; C116822:hns protein, E coli