Nucleotide sequence of a crustacean 18S ribosomal RNA gene and secondary structure of eukaryotic small subunit ribosoraal RNAs

Abstract

The primary structure of the gene for 18 S rRNA of the crustacean Artemia salina was determined. The sequence has been aligned with 13 other small ribosomal subunit RNA sequences of eukaryotic, archaebacterial, eubacterial, chloroplastic and plant mitochondrial origin. Secondary structure models for these RNAs were derived on the basis of previously proposed models and additional comparative evidence found in the alignment. Although there is a general similarity in the secondary structure models for eukaryotes and prokaryotes, the evidence seems to indicate a different topology in a central area of the structures.

Primary and secondary structure of the 18 S ribosomal RNA of the insect species Tenebrio molitor

“…An apparent exception to the numbering rules is made for helices 43 and 44, which are separated by an internal rather than by a multibranched loop. The reason is that in the partial secondary structure model for this E21 area This extra sequence can be folded into a hairpin was proposed by Nelles and co-workers [2]. structure bearing the number E43-1, which is abRecently, other authors [3,7,10,1 l] advocated sent in the remaining known 18 S rRNAs.…”

“…Secondary structure model for T. molitor 18 S rRNA Fig.3 shows the secondary structure model derived for the 18 S rRNA of T. molitor. Helices are numbered according to the principle set forth previously [2], i.e. in order of their occurrence when the sequence is scanned from the 5 '-to 3 '-terminus.…”

“…Renumbering of the helices with respect to previous 'models [ 1,2] was necessary because the availability of an increasing number of sequences allows additional secondary structure elements to be discerned. The two helices forming the pseudoknot structure…”

“…The partial length as well as in secondary structure. Whereas model proposed in [2] was taken as a starting point prokaryotic srRNAs comprise a single helix in this and additional helices were constructed. Most euarea, namely the protein S&binding helix [5] karyotic srRNAs can be folded into a structure fig.3, E21-1, E21~2 and E21-6 can be proven by compensating substitutions.…”

“…The Metazoa are represented in this collection by eight different species, of which there are six vertebrates and only two invertebrates, viz. Arfemia sulina (phylum Arthropoda, class Crustacea) [2] and Caenorhabditis elegans (phylum Nemathelminthes, class Nematoda) [3]. Here, we report the primary structure of the srRNA from another Arthropod, Tenebrio molitor (class Insecta).…”