Faculty Opinions recommendation of Membrane binding of the bacterial signal recognition particle receptor involves two distinct binding sites.

Cotranslational protein targeting in bacteria is mediated by the signal recognition particle (SRP) and FtsY, the bacterial SRP receptor (SR). FtsY is homologous to the SRα subunit of eukaryotes, which is tethered to the membrane via its interaction with the membrane-integral SRβ subunit. Despite the lack of a membrane-anchoring subunit, 30% of FtsY in Escherichia coli are found stably associated with the cytoplasmic membrane. However, the mechanisms that are involved in this membrane association are only poorly understood. Our data indicate that membrane association of FtsY involves two distinct binding sites and that binding to both sites is stabilized by blocking its GTPase activity. Binding to the first site requires only the NG-domain of FtsY and confers protease protection to FtsY. Importantly, the SecY translocon provides the second binding site, to which FtsY binds to form a carbonate-resistant 400-kD FtsY–SecY translocon complex. This interaction is stabilized by the N-terminal A-domain of FtsY, which probably serves as a transient lipid anchor.

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Faculty Opinions recommendation of Structural basis for the function of the beta subunit of the eukaryotic signal recognition particle receptor.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1002677.191319 ◽

2003 ◽

Author(s):

Elena Conti

Keyword(s):

Signal Recognition Particle ◽

Beta Subunit ◽

Structural Basis ◽

Signal Recognition ◽

Signal Recognition Particle Receptor

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Structural analysis of the SRP Alu domain from Plasmodium falciparum reveals a non-canonical open conformation

Communications Biology ◽

10.1038/s42003-021-02132-y ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Komal Soni ◽

Georg Kempf ◽

Karen Manalastas-Cantos ◽

Astrid Hendricks ◽

Dirk Flemming ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Binding Sites ◽

Signal Recognition Particle ◽

Signal Recognition ◽

Closed Conformation ◽

Open Conformation ◽

Structural Database ◽

Alu Rna ◽

Species Specific ◽

Protozoan Species

AbstractThe eukaryotic signal recognition particle (SRP) contains an Alu domain, which docks into the factor binding site of translating ribosomes and confers translation retardation. The canonical Alu domain consists of the SRP9/14 protein heterodimer and a tRNA-like folded Alu RNA that adopts a strictly ‘closed’ conformation involving a loop-loop pseudoknot. Here, we study the structure of the Alu domain from Plasmodium falciparum (PfAlu), a divergent apicomplexan protozoan that causes human malaria. Using NMR, SAXS and cryo-EM analyses, we show that, in contrast to its prokaryotic and eukaryotic counterparts, the PfAlu domain adopts an ‘open’ Y-shaped conformation. We show that cytoplasmic P. falciparum ribosomes are non-discriminative and recognize both the open PfAlu and closed human Alu domains with nanomolar affinity. In contrast, human ribosomes do not provide high affinity binding sites for either of the Alu domains. Our analyses extend the structural database of Alu domains to the protozoan species and reveal species-specific differences in the recognition of SRP Alu domains by ribosomes.

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