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335  structures 696  species 2  interactions 855  sequences 18  architectures

Family: Ribonuclease (PF00545)

Summary: ribonuclease

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Ribonuclease Edit Wikipedia article

ribonuclease
Identifiers
Symbol Ribonuclease
Pfam PF00545
InterPro IPR000026
SCOP 1brn
SUPERFAMILY 1brn

Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within the EC 2.7 (for the phosphorolytic enzymes) and 3.1 (for the hydrolytic enzymes) classes of enzymes.

Function[edit]

All organisms studied contain many RNases of many different classes, showing that RNA degradation is a very ancient and important process. As well as cleaning of cellular RNA that is no longer required, RNases play key roles in the maturation of all RNA molecules, both messenger RNAs that carry genetic material for making proteins, and non-coding RNAs that function in varied cellular processes. In addition, active RNA degradation systems are a first defense against RNA viruses, and provide the underlying machinery for more advanced cellular immune strategies such as RNAi.

Some cells also secrete copious quantities of non-specific RNases such as A and T1. RNases are, therefore, extremely common, resulting in very short lifespans for any RNA that is not in a protected environment. It is worth noting that all intracellular RNAs are protected from RNase activity by a number of strategies including 5' end capping, 3' end polyadenylation, and folding within an RNA protein complex (ribonucleoprotein particle or RNP).

Another mechanism of protection is ribonuclease inhibitor (RI), which comprises a relatively large fraction of cellular protein (~0.1%) in some cell types, and which binds to certain ribonucleases with the highest affinity of any protein-protein interaction; the dissociation constant for the RI-RNase A complex is ~20 fM under physiological conditions. RI is used in most laboratories that study RNA to protect their samples against degradation from environmental RNases.

Similar to restriction enzymes, which cleave highly specific sequences of double-stranded DNA, a variety of endoribonucleases that recognize and cleave specific sequences of single-stranded RNA have been recently classified.

RNases play a critical role in many biological processes, including angiogenesis and self-incompatibility in flowering plants (angiosperms). Also, RNases in prokaryotic toxin-antitoxin systems are proposed to function as plasmid stability loci, and as stress-response elements when present on the chromosome.

Classification[edit]

Major types of endoribonucleases[edit]

Structure of RNase A
  • EC 3.1.27.5: RNase A is an RNase that is commonly used in research. RNase A (e.g., bovine pancreatic ribonuclease A: PDB 2AAS) is one of the hardiest enzymes in common laboratory usage; one method of isolating it is to boil a crude cellular extract until all enzymes other than RNase A are denatured. It is specific for single-stranded RNAs. It cleaves the 3'-end of unpaired C and U residues, ultimately forming a 3'-phosphorylated product via a 2',3'-cyclic monophosphate intermediate.[1]
  • EC 3.1.26.4: RNase H is a ribonuclease that cleaves the RNA in a DNA/RNA duplex to produce ssDNA. RNase H is a non-specific endonuclease and catalyzes the cleavage of RNA via a hydrolytic mechanism, aided by an enzyme-bound divalent metal ion. RNase H leaves a 5'-phosphorylated product.
  • EC number 3.1.??: RNase I cleaves 3'-end of ssRNA at all dinucleotide bonds leaving a 5'-hydroxyl, and 3'-phosphate, via a 2',3'-cyclic monophosphate intermediate.
  • EC 3.1.26.3: RNase III is a type of ribonuclease that cleaves rRNA (16s rRNA and 23s rRNA) from transcribed polycistronic RNA operon in prokaryotes. It also digests double strands RNA (dsRNS)-Dicer family of RNAse, cutting pre-miRNA (60–70bp long) at a specific site and transforming it in miRNA (22–30bp), that is actively involved in the regulation of transcription and mRNA life-time.
  • EC number 3.1.26.-??: RNase L is an interferon-induced nuclease that, upon activation, destroys all RNA within the cell
  • EC 3.1.26.5: RNase P is a type of ribonuclease that is unique in that it is a ribozyme – a ribonucleic acid that acts as a catalyst in the same way as an enzyme. Its function is to cleave off an extra, or precursor, sequence on tRNA molecules. RNase P is one of two known multiple turnover ribozymes in nature (the other being the ribosome). A form of RNase P that is a protein and does not contain RNA has recently been discovered.[2]
  • EC number 3.1.??: RNase PhyM is sequence specific for single-stranded RNAs. It cleaves 3'-end of unpaired A and U residues.
  • EC 3.1.27.3: RNase T1 is sequence specific for single-stranded RNAs. It cleaves the 9'-end nitrogen atom, which connects to a phosphate group, of unpaired G residues.
  • EC 3.1.27.1: RNase T2 is sequence specific for single-stranded RNAs. It cleaves 3'-end of all 4 residues, but preferentially 3'-end of As.
  • EC 3.1.27.4: RNase U2 is sequence specific for single-stranded RNAs. It cleaves 3'-end of unpaired A residues.
  • EC 3.1.27.8: RNase V1 is non-sequence specific for double-stranded RNAs. It cleaves base-paired nucleotide residues.

Major types of exoribonucleases[edit]

  • EC number 3.1.??: RNase R is a close homolog of RNase II, but it can, unlike RNase II, degrade RNA with secondary structures without help of accessory factors.
  • EC number 3.1.??: RNase T is the major contributor for the 3'-to-5' maturation of many stable RNAs.

RNase contamination during RNA extraction[edit]

The extraction of RNA in molecular biology experiments is greatly complicated by the presence of ubiquitious and hardy RNases that degrade RNA samples. Certain RNases can be extremely hardy and inactivating them is difficult compared to neutralizing DNases. In addition to the cellular RNases that are released there are several RNases that are present in the environment. RNases have evolved to have many extracellular functions in various organisms.[3][4][5] For example, RNase 7, a member of the RNase A superfamily is secreted by human skin and serves as a potent antipathogen defence.[6][7] In these secreted RNases, the enzymatic RNase activity may not even be necessary for it's new, exapted function. For example immune RNases act by destabilizing the cell membranes of bacteria.[8][9]

External links[edit]

References[edit]

  1. ^ Cuchillo, C. M.; Nogués, M. V.; Raines, R. T. (2011). "Bovine pancreatic ribonuclease: Fifty years of the first enzymatic reaction mechanism". Biochemistry 50: 7835–7841. doi:10.1021/bi201075b. PMC 3172371. PMID 21838247. 
  2. ^ J. Holzmann, P. Frank, E. Löffler, K. Bennett, C. Gerner & W. Rossmanith (2008). "RNase P without RNA: Identification and functional reconstitution of the human mitochondrial tRNA processing enzyme". Cell 135 (3): 462–474. doi:10.1016/j.cell.2008.09.013. PMID 18984158. 
  3. ^ Rossier, O.; Dao, J.; Cianciotto, N. P. (2009). "A type II secreted RNase of Legionella pneumophila facilitates optimal intracellular infection of Hartmannella vermiformis". Microbiology 155 (3): 882. doi:10.1099/mic.0.023218-0.  edit
  4. ^ Luhtala, N.; Parker, R. (2010). "T2 Family ribonucleases: Ancient enzymes with diverse roles". Trends in Biochemical Sciences 35 (5): 253. doi:10.1016/j.tibs.2010.02.002.  edit
  5. ^ Dyer, K. D.; Rosenberg, H. F. (2006). "The RNase a superfamily: Generation of diversity and innate host defense". Molecular Diversity 10 (4): 585. doi:10.1007/s11030-006-9028-2.  edit
  6. ^ Harder, J. (2002). "RNase 7, a Novel Innate Immune Defense Antimicrobial Protein of Healthy Human Skin". Journal of Biological Chemistry 277 (48): 46779. doi:10.1074/jbc.M207587200.  edit
  7. ^ Köten, B.; Simanski, M.; Gläser, R.; Podschun, R.; Schröder, J. M.; Harder, J. R. (2009). "RNase 7 Contributes to the Cutaneous Defense against Enterococcus faecium". PLoS ONE 4 (7): e6424. doi:10.1371/journal.pone.0006424.  edit
  8. ^ Huang, Y. -C.; Lin, Y. -M.; Chang, T. -W.; Wu, S. -J.; Lee, Y. -S.; Chang, M. D. -T.; Chen, C.; Wu, S. -H.; Liao, Y. -D. (2006). "The Flexible and Clustered Lysine Residues of Human Ribonuclease 7 Are Critical for Membrane Permeability and Antimicrobial Activity". Journal of Biological Chemistry 282 (7): 4626. doi:10.1074/jbc.M607321200.  edit
  9. ^ Rosenberg, H. F. (2008). "RNase a ribonucleases and host defense: An evolving story". Journal of Leukocyte Biology 83 (5): 1079. doi:10.1189/jlb.1107725.  edit
  • D'Alessio G and Riordan JF, eds. (1997) Ribonucleases: Structures and Functions, Academic Press.
  • Gerdes K, Christensen SK and Lobner-Olesen A (2005). "Prokaryotic toxin-antitoxin stress response loci". Nat. Rev. Microbiol. (3) 371–382.

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This enzyme hydrolyses RNA and oligoribonucleotides.

Literature references

  1. Buckle AM, Fersht AR; , Biochemistry 1994;33:1644-1653.: Subsite binding in an RNase: structure of a barnase- tetranucleotide complex at 1.76-A resolution. PUBMED:8110767 EPMC:8110767


External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR000026

Ribonuclease N1 (RNase N1) is a guanine-specific ribonuclease from fungi. RNase T1 and other bacteria RNases are related.

The enzyme hydrolyses the phosphodiester bonds in RNA and oligoribonucleotides [PUBMED:8110767], resulting in 3'-nucleoside monophosphates via 2',3'-cyclophosphate intermediates.

Gene Ontology

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Domain organisation

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  Seed
(80)
Full
(855)
Representative proteomes NCBI
(839)
Meta
(28)
RP15
(68)
RP35
(167)
RP55
(250)
RP75
(302)
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  Seed
(80)
Full
(855)
Representative proteomes NCBI
(839)
Meta
(28)
RP15
(68)
RP35
(167)
RP55
(250)
RP75
(302)
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External links

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Pfam alignments:

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Seed source: SCOP
Previous IDs: ribonuclease;
Type: Domain
Author: Bateman A
Number in seed: 80
Number in full: 855
Average length of the domain: 88.20 aa
Average identity of full alignment: 33 %
Average coverage of the sequence by the domain: 48.99 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 21.3 21.3
Trusted cut-off 21.7 21.3
Noise cut-off 20.3 20.9
Model length: 83
Family (HMM) version: 15
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Species distribution

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Interactions

There are 2 interactions for this family. More...

Ribonuclease Barstar

Structures

For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Ribonuclease domain has been found. There are 335 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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