Rhizobiales-2 RNA motif

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Rhizobiales-2 RNA
Rhizobiales-2-RNA.svg
Consensus secondary structure of Rhizobiales-2 RNAs
Identifiers
SymbolRhizobiales-2
Rfam RF01723
Other data
RNA typesRNA
Domain(s) Hyphomicrobiales
PDB structures PDBe

The Rhizobiales-2 RNA motif is a set of RNAs found in certain bacteria that are presumed to be homologous because they conserve a common primary and secondary structure (see diagram). [1] The motif was discovered using bioinformatics, and is found only within bacteria that belong to the order Hyphomicrobiales (formerly Rhizobiales), in turn a kind of alphaproteobacteria. Because Rhizobiales-2 RNAs are not consistently located in proximity to genes of a consistent class or function, these RNAs are presumed to function as non-coding RNAs.

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SucA RNA motif

The sucA RNA motif is a conserved RNA structure found in bacteria of the order Burkholderiales. RNAs within this motif are always found in the presumed 5' UTR of sucA genes. sucA encodes a subunit of an enzyme that participates in the citric acid cycle by synthesizing succinyl-CoA from 2-oxoglutarate. A part of the conserved structure overlaps predicted Shine-Dalgarno sequences of the downstream sucA genes. Because of the RNA motif's consistent gene association and a possible mechanism for sequestering the ribosome binding site, it was proposed that the sucA RNA motif corresponds to a cis-regulatory element. Its relatively complex secondary structure could indicate that it is a riboswitch. However, the function of this RNA motif remains unknown.

Chlorobi-1 RNA motif

The Chlorobi-1 RNA motif is a conserved RNA secondary structure identified by bioinformatics. It is predicted to be used only by Chlorobi, a phylum of bacteria. The motif consists of two stem-loops that are followed by an apparent rho-independent transcription terminator. The motif is presumed to function as an independently transcribed non-coding RNA.

Chlorobi-RRM RNA motif

The Chlorobi-RRM RNA motif is a conserved RNA structure identified by bioinformatics. It is found within bacteria in the phylum Chlorobi, and is exclusively detected in the presumed 5' untranslated regions of genes that encode putative RNA-binding proteins. Since many RNA-binding proteins regulate their own expression in a feedback mechanism by binding or acting up their 5' UTR, it was proposed that the Chlorobi-RRM is a component in an analogous feedback mechanism. Structurally, the motif consists of two stem-loops, the second of which might function as a rho-independent transcription terminator.

Downstream-peptide motif

The Downstream-peptide motif refers to a conserved RNA structure identified by bioinformatics in the cyanobacterial genera Synechococcus and Prochlorococcus and one phage that infects such bacteria. It was also detected in marine samples of DNA from uncultivated bacteria, which are presumably other species of cyanobacteria.

Glutamine riboswitch Glutamine-binding RNA structure

The glutamine riboswitch is a conserved RNA structure that was predicted by bioinformatics. It is present in a variety of lineages of cyanobacteria, as well as some phages that infect cyanobacteria. It is also found in DNA extracted from uncultivated bacteria living in the ocean that are presumably species of cyanobacteria.

Flavo-1 RNA motif

The Flavo-1 RNA motif is a conserved RNA structure that was identified by bioinformatics. The vast majority of Flavo-1 RNAs are found in Flavobacteria, but some were detected in the phylum Bacteroidetes, which contains Flavobacteria, or the phylum Spirochaetes, which is evolutionarily related to Bacteroidetes. It was presumed that Flavo-1 RNAs function as non-coding RNAs.

Flg-Rhizobiales RNA motif

The flg-Rhizobiales RNA motif is an RNA structure that is conserved in certain bacteria. All known flg-Rhizobiales RNAs are located in the presumptive 5' untranslated regions of operons that contain genes whose functions relate to the creation of flagellar basal bodies. The flg-Rhizobiales RNAs are restricted to the Hyphomicrobiales, an order of alphaproteobacteria, although only some Rhizobiales bacterial are predicted to use flg-Rhizobiales RNAs. The exact function of these RNAs is unknown, although it is hypothesized that they have a cis-regulatory function in controlling expression of the downstream operons.

GyrA RNA motif

The gyrA RNA motif is a conserved RNA structure identified by bioinformatics. The RNAs are present in multiple species of bacteria within the order Pseudomonadales. This order contains the genus Pseudomonas, which includes the opportunistic human pathogen Pseudomonas aeruginosa and Pseudomonas syringae, a plant pathogen.

Methylobacterium-1 RNA motif

The Methylobacterium-1 RNA motif is a conserved RNA structure discovered using bioinformatics. Almost all known examples of this RNA are found in DNA extracted from marine bacteria. However, one instance is predicted in Methylobacterium sp. 4-46, a species of alphaproteobacteria. The motif is presumed to function as a non-coding RNA.

mraW RNA motif

The mraW RNA motif is a conserved, structured RNA found in certain bacteria. Specifically, it is predicted in many, though not all, species of actinobacteria, and especially within the genus Mycobacterium. Structurally, the motif consists of a hairpin with a highly conserved terminal loop sequence. mraW RNAs are consistently in the presumed 5' untranslated regions of mraW genes. These mraW genes likely form operons with immediately downstream ftsI genes, and multiple types of mur genes. These genes are associated with peptidoglycan synthesis, and it was hypothesized that the mraW RNA motif might regulate these genes.

MsiK RNA motif

The msiK RNA motif describes a conserved RNA structure discovered using bioinformatics. The RNA is always found in the presumed 5' untranslated regions of genes annotated as msiK, and is therefore hypothesized to be an RNA-based cis-regulatory element that regulates these genes.

The nuoG RNA motif is a conserved RNA structure detected by bioinformatics. It is located in the presumed 5' untranslated regions of nuoG genes. This gene and the downstream genes probably comprise an operon that encodes various subunits of ubiquinone reductase enzyme.

Pfl RNA motif

The pfl RNA motif refers to a conserved RNA structure present in some bacteria and originally discovered using bioinformatics. pfl RNAs are consistently present in genomic locations that likely correspond to the 5' untranslated regions of protein-coding genes. This arrangement in bacteria is commonly associated with cis-regulatory elements. Moreover, they are in presumed 5' UTRs of multiple non-homologous genes, suggesting that they function only in these locations. Additional evidence of cis-regulatory function came from the observation that predicted rho-independent transcription terminators overlap pfl RNAs. This overlap suggests that the alternate secondary structures of pfl RNA and the transcription terminator stem-loops compete with each other, and this is a common mechanism for cis gene control in bacteria.

potC RNA motif

The potC RNA motif is a conserved RNA structure discovered using bioinformatics. The RNA is detected only in genome sequences derived from DNA that was extracted from uncultivated marine bacteria. Thus, this RNA is present in environmental samples, but not yet found in any cultivated organism. potC RNAs are located in the presumed 5' untranslated regions of genes predicted to encode either membrane transport proteins or peroxiredoxins. Therefore, it was hypothesized that potC RNAs are cis-regulatory elements, but their detailed function is unknown.

RadC RNA motif

The radC RNA motif is a conserved RNA structure identified by bioinformatics. The radC RNA motif is found in certain bacteria where it is consistent located in the presumed 5' untranslated regions of genes whose encoded proteins bind DNA are interact with other proteins that bind DNA. These proteins include integrases, methyltransferases that might methylate DNA, proteins that inhibit restriction enzymes and radC genes. Although radC genes were thought to encode DNA repair proteins, this conclusion was based on mutation data that was later shown to affect a different gene. However, it is still possible that radC genes play some DNA-related role. No radC RNAs have been detected in any purified phage whose sequence was available as of 2010, although integrases are often used by phages.

rne-II RNA motif

The rne-II RNA motif is a conserved RNA structure identified using bioinformatics. It is detected only in species classified within the family Pseudomonadaceae, a group of gammaproteobacteria. rne-II RNAs are consistently located in the presumed 5' untranslated regions of genes that encode Ribonuclease E. The RNase E 5' UTR element is a previously identified RNA structure that is also found in the 5' UTRs of RNase E genes. However, the latter motif is found only in enterobacteria, and the two motifs have apparently unrelated structure. In view of their differences, it was hypothesized that rne-II RNAs fulfill the same functional role as RNase E 5' UTR elements, which is to regulate the levels of RNase E proteins by acting as a substrate for RNase E. Thus, when concentrations of RNase E are high, they will degrade their own messenger RNA.

SucA-II RNA motif

The sucA-II RNA motif is a conserved RNA structure identified by bioinformatics. It is consistently found in the presumed 5' untranslated regions of sucA genes, which encode Oxoglutarate dehydrogenase enzymes that participate in the citric acid cycle. Given this arrangement, sucA-II RNAs might regulate the downstream sucA gene. This genetic arrangement is similar to the previously reported sucA RNA motif. However, sucA-II RNAs are found only in bacteria classified within the genus Pseudomonas, whereas the previously reported motif is found only in betaproteobacteria.

Termite-flg RNA motif

The Termite-flg RNA motif is a conserved RNA structure identified by bioinformatics. Genomic sequences corresponding to Termite-flg RNAs have been identified only in uncultivated bacteria present in the termite hindgut. As of 2010 it has not been identified in the DNA of any cultivated species, and is thus an example of RNAs present in environmental samples.

YjdF RNA motif

The yjdF RNA motif is a conserved RNA structure identified using bioinformatics. Most yjdF RNAs are located in bacteria classified within the phylum Firmicutes. A yjdF RNA is found in the presumed 5' untranslated region of the yjdF gene in Bacillus subtilis, and almost all yjdF RNAs are found in the 5' UTRs of homologs of this gene. The function of the yjdF gene is unknown, but the protein that it is predicted to encode is classified by the Pfam Database as DUF2992.

Zeta-<i>pan</i> RNA motif

The Zeta-pan RNA motif is a conserved RNA structure that was discovered by bioinformatics. Zeta-pan motif RNAs are found in Zetaproteobacteria.

References

  1. Weinberg Z, Wang JX, Bogue J, et al. (March 2010). "Comparative genomics reveals 104 candidate structured RNAs from bacteria, archaea and their metagenomes". Genome Biol. 11 (3): R31. doi:10.1186/gb-2010-11-3-r31. PMC   2864571 . PMID   20230605.