Change search
ReferencesLink to record
Permanent link

Direct link
Secondary structure of two regions in expansion segments ES3 and ES6 with the potential of forming a tertiary interaction in eukaryotic 40S ribosomal subunits
Södertörn University, School of Chemistry, Biology, Geography and Environmental Science. Stockholm University.
Södertörn University, School of Chemistry, Biology, Geography and Environmental Science.
2004 (English)In: RNA: A publication of the RNA Society, ISSN 1355-8382, E-ISSN 1469-9001, Vol. 10, no 3, 403-411 p.Article in journal (Refereed) Published
Abstract [en]

The 18S rRNA of the small eukaryotic ribosomal subunit contains several expansion segments. Electron microscopy data indicate that two of the largest expansion segments are juxtaposed in intact 40S subunits, and data from phylogenetic sequence comparisons indicate that these two expansion segments contain complementary sequences that could form a direct tertiary interaction on the ribosome. We have investigated the secondary structure of the two expansion segments in the region around the putative tertiary interaction. Ribosomes from yeast, wheat, and mouse-three organisms representing separate eukaryotic kingdoms-were isolated, and the structure of ES3 and part of the ES6 region were analyzed using the single-strand-specific chemical reagents CMCT and DMS and the double-strand-specific ribonuclease V1. The modification patterns were analyzed by primer extension and gel electrophoresis on an ABI 377 automated DNA sequencer. The investigated sequences were relatively exposed to chemical and enzymatic modification. This is in line with their indicated location on the surface at the solvent side of the subunit. The complementary ES3 and ES6 sequences were clearly inaccessible to single-strand modification, but available for cleavage by double-strand-specific RNase V1. The results are compatible with a direct helical interaction between bases in ES3 and ES6. Almost identical results were obtained with ribosomes from the three organisms investigated.

Place, publisher, year, edition, pages
2004. Vol. 10, no 3, 403-411 p.
National Category
Biochemistry and Molecular Biology
URN: urn:nbn:se:sh:diva-17624DOI: 10.1261/rna.5135204ISI: 000189115400008PubMedID: 14970386ScopusID: 2-s2.0-10744227895OAI: diva2:577107
Available from: 2012-12-14 Created: 2012-12-14 Last updated: 2017-02-13Bibliographically approved
In thesis
1. Ribosome and ribosomal RNA Structure: An experimental and computational analysis of expansion segments in eukaryotic ribosomal RNA
Open this publication in new window or tab >>Ribosome and ribosomal RNA Structure: An experimental and computational analysis of expansion segments in eukaryotic ribosomal RNA
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Ribosomes are large ribonucleoprotein complexes which incorporate amino acids into peptide chains during translational process in all types of living cells. The eukaryotic ribosome is larger compared to its prokaryotic counterpart. The size differences are due to a larger protein part and that the rRNA contains eukaryote specific expansion segments (ES). Cryo-EM reconstruction has visualized many ES on the ribosomal surface which have given clues about function and structural features. However, the secondary structures of most ES are unknown or ill defined. In this thesis, the secondary and also to a certain extent the tertiary structures of several ES are determined by using computational methods and biochemical experimental techniques. The juxtaposition of ES6 close to ES3 in the Cryo-EM image of the yeast ribosome suggested that ES3 and ES6 might interact. A computational analysis of more than 2900 sequences shows that a complementary helical region of seven to nine contiguous base pairs can form between ES3 and ES6 in almost all analyzed sequences. Biochemical in situ experiments support the proposed interaction. Secondary structure models are presented for ES3 and ES6 in 18S rRNA and ES39 in 28S rRNA, where homologous structural elements could be modeled in the experimentally analyzed ribosomes from fungi, plants and mammals. The structure models were further supported by computational methods where the ES6 structure and the ES39 structure could be formed in more than 6000 and 900 sequences respectively. A tertiary structure model of ES3 and ES6 including the helical interaction is presented. An in vitro transcribed and folded ES6 sequence differed from that observed in situ, suggesting that chaperones, ribosomal proteins, and/or the tertiary rRNA interaction could be involved in the in vivo folding of ES6. An analysis of the similarities between ES39 structures suggests that it might be under selective constraint to preserve its secondary structure.

Place, publisher, year, edition, pages
Stockholm: Wenner-Gren Institute for Experimental Biology, Stockholm university, 2008. 72 p.
eukaryotes, expansion segment, ribosomes, rRNA, secondary structure, structure of rRNA.
National Category
Cell and Molecular Biology
urn:nbn:se:sh:diva-32043 (URN)978-91-7155-603-5 (ISBN)
Public defence
2008-05-23, William-Olssonsalen, Geovetenskapens hus, Svante Arrhenius väg 8 A, Stockholm, 13:00 (English)
Available from: 2017-02-13 Created: 2017-02-13 Last updated: 2017-02-13Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMedScopus

Search in DiVA

By author/editor
Alkemar, GunnarNygård, Odd
By organisation
School of Chemistry, Biology, Geography and Environmental Science
In the same journal
RNA: A publication of the RNA Society
Biochemistry and Molecular Biology

Search outside of DiVA

GoogleGoogle Scholar

Altmetric score

Total: 82 hits
ReferencesLink to record
Permanent link

Direct link