S15

Ribosomal protein leader A ribosomal protein leader is a mechanism used in cells to control the cellular concentration of a protein that forms a part of the ribosome, and to make sure that the concentration is neither too high nor too low. Ribosomal protein leaders are RNA ...

s perform an important regulatory function in

ribosome biogenesis Ribosome biogenesis is the process of making ribosomes. In prokaryotes, this process takes place in the cytoplasm with the transcription of many ribosome gene operons. In eukaryotes, it takes place both in the cytoplasm and in the nucleolus. ...

. They were used as an autoregulatory mechanism to control the concentration of

ribosomal protein A ribosomal protein (r-protein or rProtein) is any of the proteins that, in conjunction with rRNA, make up the ribosomal subunits involved in the cellular process of translation. ''E. coli'', other bacteria and Archaea have a 30S small subunit ...

s S15. The structure is located in the 5′ untranslated regions of

mRNAs In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of synthesizing a protein. mRNA is created during the p ...

encoding

ribosomal proteins A ribosomal protein (r-protein or rProtein) is any of the proteins that, in conjunction with rRNA, make up the ribosomal subunits involved in the cellular process of translation. ''E. coli'', other bacteria and Archaea have a 30S small subunit an ...

S15 (rpsO). Multiple distinct structural types of S15 ribosomal protein leaders are known in different organisms. The ''

E. coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escherichia'' that is commonly foun ...

'' ribosomal S15 leader is an RNA element that can form two alternative

structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

found in the ribosomal S15 protein. One of the two alternate structures is a series of three hairpins, the other includes a

pseudoknot __NOTOC__ A pseudoknot is a nucleic acid secondary structure containing at least two stem-loop structures in which half of one stem is intercalated between the two halves of another stem. The pseudoknot was first recognized in the turnip yellow ...

. This structure causes translational regulation of the S15

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

. Only the final two hairpins are conserved in other species. Another example for

Bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

was predicted in

Flavobacteria The class Flavobacteriia is composed of a single class of environmental bacteria. It contains the family Flavobacteriaceae, which is the largest family in the phylum Bacteroidota. This class is widely distributed in soil, fresh, and seawater habi ...

. The secondary structure of his putative ribosomal leader consists of a hairpin in most species. However, some species lack this hairpin. Such a lack of apparent secondary structure would be unusual for a ribosomal leader, which makes this candidate ribosomal leader a less certain prediction. Two examples in

Archaea Archaea ( ) is a Domain (biology), domain of organisms. Traditionally, Archaea only included its Prokaryote, prokaryotic members, but this has since been found to be paraphyletic, as eukaryotes are known to have evolved from archaea. Even thou ...

(one in

Halobacteria Haloarchaea (halophilic archaea, halophilic archaebacteria, halobacteria) are a class (biology), class of prokaryotic archaea under the phylum Euryarchaeota, found in water Saturated and unsaturated compounds, saturated or nearly saturated with ...

and one in

Methanomicrobia Methanomicrobia is a class of archaeans in the phylum Methanobacteriota. Phylogeny The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information ...

) were predicted. In this structure, similarities between the

rRNA Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal ...

binding site of the S15

and the S15

ribosomal protein leader A ribosomal protein leader is a mechanism used in cells to control the cellular concentration of a protein that forms a part of the ribosome, and to make sure that the concentration is neither too high nor too low. Ribosomal protein leaders are RNA ...

binding site were detected. This suggests that the ribosomal leaders in these organisms function by mimicking the S15 binding site in rRNA. S15 ribosomal protein leader

References

External links

* Ribosomal protein leader {{molecular-cell-biology-stub

See also

References

External links