scholarly journals Archaea Signal Recognition Particle Shows the Way

Archaea ◽  
2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Christian Zwieb ◽  
Shakhawat Bhuiyan
Keyword(s):  
Signal Sequence ◽  
Signal Recognition Particle ◽  
Signal Recognition ◽  
R Region ◽  
Exit Tunnel ◽  
And Function ◽  
Hydrolysis Of ◽  
Subordinate Role ◽  
Srp Rna

Archaea SRP is composed of an SRP RNA molecule and two bound proteins named SRP19 and SRP54. Regulated by the binding and hydrolysis of guanosine triphosphates, the RNA-bound SRP54 protein transiently associates not only with the hydrophobic signal sequence as it emerges from the ribosomal exit tunnel, but also interacts with the membrane-associated SRP receptor (FtsY). Comparative analyses of the archaea genomes and their SRP component sequences, combined with structural and biochemical data, support a prominent role of the SRP RNA in the assembly and function of the archaea SRP. The 5e motif, which in eukaryotes binds a 72 kilodalton protein, is preserved in most archaea SRP RNAs despite the lack of an archaea SRP72 homolog. The primary function of the 5e region may be to serve as a hinge, strategically positioned between the small and large SRP domain, allowing the elongated SRP to bind simultaneously to distant ribosomal sites. SRP19, required in eukaryotes for initiating SRP assembly, appears to play a subordinate role in the archaea SRP or may be defunct. The N-terminal A region and a novel C-terminal R region of the archaea SRP receptor (FtsY) are strikingly diverse or absent even among the members of a taxonomic subgroup.

scholarly journals Mechanisms of membrane protein biogenesis

2014 ◽  
Vol 70 (a1) ◽  
pp. C1161-C1161
Author(s):  
Irmgard Sinning
Keyword(s):  
Membrane Proteins ◽  
Signal Sequence ◽  
Signal Recognition Particle ◽  
Signal Recognition ◽  
Protein Biogenesis ◽  
Cargo Proteins ◽  
Target Membrane ◽  
Hydrophobic Nature ◽  
Correct Target ◽  
Srp Rna

More than 25% of the cellular proteome comprise membrane proteins that have to be inserted into the correct target membrane. Most membrane proteins are delivered to the membrane by the signal recognition particle (SRP) pathway which relies on the recognition of an N-terminal signal sequence. In contrast to this co-translational mechanism, which avoids problems due to the hydrophobic nature of the cargo proteins, tail-anchored (TA) membrane proteins utilize a post-translational mechanism for membrane insertion – the GET pathway (guided entry of tail-anchored membrane proteins). The SRP and GET pathways are both regulated by GTP and ATP binding proteins of the SIMIBI family. However, in the SRP pathway the SRP RNA plays a unique regulatory role. Recent insights into eukaryotic SRP will be discussed.

scholarly journals Anti-cooperative assembly of the SRP19 and SRP68/72 components of the signal recognition particle

2008 ◽  
Vol 415 (3) ◽  
pp. 429-437 ◽  
Author(s):  
Tuhin Subhra Maity ◽  
Howard M. Fried ◽  
Kevin M. Weeks
Keyword(s):  
Electrostatic Interactions ◽  
Signal Recognition Particle ◽  
Cooperative Binding ◽  
Signal Recognition ◽  
Parallel Orientation ◽  
Domain Interactions ◽  
Cooperative Assembly ◽  
Srp Rna ◽  
Antagonistic Interactions

The mammalian SRP (signal recognition particle) represents an important model for the assembly and role of inter-domain interactions in complex RNPs (ribonucleoproteins). In the present study we analysed the interdependent interactions between the SRP19, SRP68 and SRP72 proteins and the SRP RNA. SRP72 binds the SRP RNA largely via non-specific electrostatic interactions and enhances the affinity of SRP68 for the RNA. SRP19 and SRP68 both bind directly and specifically to the same two RNA helices, but on opposite faces and at opposite ends. SRP19 binds at the apices of helices 6 and 8, whereas the SRP68/72 heterodimer binds at the three-way junction involving RNA helices 5, 6 and 8. Even though both SRP19 and SRP68/72 stabilize a similar parallel orientation for RNA helices 6 and 8, these two proteins bind to the RNA with moderate anti-cooperativity. Long-range anti-cooperative binding by SRP19 and SRP68/72 appears to arise from stabilization of distinct conformations in the stiff intervening RNA scaffold. Assembly of large RNPs is generally thought to involve either co-operative or energetically neutral interactions among components. By contrast, our findings emphasize that antagonistic interactions can play significant roles in assembly of multi-subunit RNPs.

scholarly journals SRPassing Co-translational Targeting: The Role of the Signal Recognition Particle in Protein Targeting and mRNA Protection

2021 ◽  
Vol 22 (12) ◽  
pp. 6284
Author(s):  
Morgana K. Kellogg ◽  
Sarah C. Miller ◽  
Elena B. Tikhonova ◽  
Andrey L. Karamyshev
Keyword(s):  
Endoplasmic Reticulum ◽  
Noncoding Rna ◽  
Protein Targeting ◽  
Signal Recognition Particle ◽  
Structure And Function ◽  
Secretory Proteins ◽  
Signal Recognition ◽  
Domains Of Life ◽  
And Function

Signal recognition particle (SRP) is an RNA and protein complex that exists in all domains of life. It consists of one protein and one noncoding RNA in some bacteria. It is more complex in eukaryotes and consists of six proteins and one noncoding RNA in mammals. In the eukaryotic cytoplasm, SRP co-translationally targets proteins to the endoplasmic reticulum and prevents misfolding and aggregation of the secretory proteins in the cytoplasm. It was demonstrated recently that SRP also possesses an earlier unknown function, the protection of mRNAs of secretory proteins from degradation. In this review, we analyze the progress in studies of SRPs from different organisms, SRP biogenesis, its structure, and function in protein targeting and mRNA protection.

scholarly journals The Signal Recognition Particle (SRP) RNA Links Conformational Changes in the SRP to Protein Targeting

2007 ◽  
Vol 18 (7) ◽  
pp. 2728-2734 ◽  
Author(s):  
Niels Bradshaw ◽  
Peter Walter
Keyword(s):  
Conformational Changes ◽  
Protein Targeting ◽  
Signal Sequence ◽  
Signal Recognition Particle ◽  
Signal Recognition ◽  
Gtp Hydrolysis ◽  
E Coli ◽  
Srp Rna ◽  
Binding Subunit

The RNA component of the signal recognition particle (SRP) is universally required for cotranslational protein targeting. Biochemical studies have shown that SRP RNA participates in the central step of protein targeting by catalyzing the interaction of the SRP with the SRP receptor (SR). SRP RNA also accelerates GTP hydrolysis in the SRP·SR complex once formed. Using a reverse-genetic and biochemical analysis, we identified mutations in the E. coli SRP protein, Ffh, that abrogate the activity of the SRP RNA and cause corresponding targeting defects in vivo. The mutations in Ffh that disrupt SRP RNA activity map to regions that undergo dramatic conformational changes during the targeting reaction, suggesting that the activity of the SRP RNA is linked to the major conformational changes in the signal sequence-binding subunit of the SRP. In this way, the SRP RNA may coordinate the interaction of the SRP and the SR with ribosome recruitment and transfer to the translocon, explaining why the SRP RNA is an indispensable component of the protein targeting machinery.

scholarly journals Structure and function of signal recognition particle (SRP)

1990 ◽  
Vol 14 (2-3) ◽  
pp. 71-72 ◽  
Author(s):  
Karin R�misch ◽  
V�ronique Ribes ◽  
Stephen High ◽  
Henrich L�tcke ◽  
David Tollervey ◽  
...  
Keyword(s):  
Signal Recognition Particle ◽  
Structure And Function ◽  
Signal Recognition ◽  
And Function

SRP RNA Remodeling by SRP68 Explains Its Role in Protein Translocation

Science ◽  
2014 ◽  
Vol 344 (6179) ◽  
pp. 101-104 ◽  
Author(s):  
Jan Timo Grotwinkel ◽  
Klemens Wild ◽  
Bernd Segnitz ◽  
Irmgard Sinning
Keyword(s):  
Ribosomal Rna ◽  
Protein Targeting ◽  
Rna Binding ◽  
Protein Translocation ◽  
Signal Recognition Particle ◽  
Structural Basis ◽  
Signal Recognition ◽  
Rna Remodeling ◽  
Srp Rna ◽  
Arginine Rich Motif

The signal recognition particle (SRP) is central to membrane protein targeting; SRP RNA is essential for SRP assembly, elongation arrest, and activation of SRP guanosine triphosphatases. In eukaryotes, SRP function relies on the SRP68-SRP72 heterodimer. We present the crystal structures of the RNA-binding domain of SRP68 (SRP68-RBD) alone and in complex with SRP RNA and SRP19. SRP68-RBD is a tetratricopeptide-like module that binds to a RNA three-way junction, bends the RNA, and inserts an α-helical arginine-rich motif (ARM) into the major groove. The ARM opens the conserved 5f RNA loop, which in ribosome-bound SRP establishes a contact to ribosomal RNA. Our data provide the structural basis for eukaryote-specific, SRP68-driven RNA remodeling required for protein translocation.

scholarly journals Circularization restores signal recognition particle RNA functionality in Thermoproteus

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
André Plagens ◽  
Michael Daume ◽  
Julia Wiegel ◽  
Lennart Randau
Keyword(s):  
Genome Rearrangement ◽  
Signal Recognition Particle ◽  
Circular Rna ◽  
Signal Recognition ◽  
Rna Molecules ◽  
Trna Splicing ◽  
Ribonucleoprotein Complexes ◽  
Domains Of Life ◽  
Thermoproteus Tenax ◽  
Srp Rna

Signal recognition particles (SRPs) are universal ribonucleoprotein complexes found in all three domains of life that direct the cellular traffic and secretion of proteins. These complexes consist of SRP proteins and a single, highly structured SRP RNA. Canonical SRP RNA genes have not been identified for some Thermoproteus species even though they contain SRP19 and SRP54 proteins. Here, we show that genome rearrangement events in Thermoproteus tenax created a permuted SRP RNA gene. The 5'- and 3'-termini of this SRP RNA are located close to a functionally important loop present in all known SRP RNAs. RNA-Seq analyses revealed that these termini are ligated together to generate circular SRP RNA molecules that can bind to SRP19 and SRP54. The circularization site is processed by the tRNA splicing endonuclease. This moonlighting activity of the tRNA splicing machinery permits the permutation of the SRP RNA and creates highly stable and functional circular RNA molecules.

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