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Mendonca A, Thandapani P, Nagarajan P, Venkatesh S, Sundaresan S. Role of microRNAs in regulation of insulin secretion and insulin signaling involved in type 2 diabetes mellitus. J Biosci 2022. [DOI: 10.1007/s12038-022-00295-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Ruiz-Márvez E, Ramírez CA, Rodríguez ER, Flórez MM, Delgado G, Guzmán F, Gómez-Puertas P, Requena JM, Puerta CJ. Molecular Characterization of Tc964, A Novel Antigenic Protein from Trypanosoma cruzi. Int J Mol Sci 2020; 21:E2432. [PMID: 32244527 PMCID: PMC7177413 DOI: 10.3390/ijms21072432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/15/2020] [Accepted: 03/17/2020] [Indexed: 11/16/2022] Open
Abstract
The Tc964 protein was initially identified by its presence in the interactome associated with the LYT1 mRNAs, which code for a virulence factor of Trypanosoma cruzi. Tc964 is annotated in the T. cruzi genome as a hypothetical protein. According to phylogenetic analysis, the protein is conserved in the different genera of the Trypanosomatidae family; however, recognizable orthologues were not identified in other groups of organisms. Therefore, as a first step, an in-depth molecular characterization of the Tc946 protein was carried out. Based on structural predictions and molecular dynamics studies, the Tc964 protein would belong to a particular class of GTPases. Subcellular fractionation analysis indicated that Tc964 is a nucleocytoplasmic protein. Additionally, the protein was expressed as a recombinant protein in order to analyze its antigenicity with sera from Chagas disease (CD) patients. Tc964 was found to be antigenic, and B-cell epitopes were mapped by the use of synthetic peptides. In parallel, the Leishmania major homologue (Lm964) was also expressed as recombinant protein and used for a preliminary evaluation of antigen cross-reactivity in CD patients. Interestingly, Tc964 was recognized by sera from Chronic CD (CCD) patients at different stages of disease severity, but no reactivity against this protein was observed when sera from Colombian patients with cutaneous leishmaniasis were analyzed. Therefore, Tc964 would be adequate for CD diagnosis in areas where both infections (CD and leishmaniasis) coexist, even though additional assays using larger collections of sera are needed in order to confirm its usefulness for differential serodiagnosis.
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Affiliation(s)
- Elizabeth Ruiz-Márvez
- Grupo de Investigación en Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 # 40- 62, Bogotá, Colombia; (E.R.-M.); (C.A.R.); (E.R.R.)
| | - César Augusto Ramírez
- Grupo de Investigación en Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 # 40- 62, Bogotá, Colombia; (E.R.-M.); (C.A.R.); (E.R.R.)
| | - Eliana Rocío Rodríguez
- Grupo de Investigación en Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 # 40- 62, Bogotá, Colombia; (E.R.-M.); (C.A.R.); (E.R.R.)
| | - Magda Mellisa Flórez
- Grupo de Investigación en Inmunotoxicología, Departamento de Farmacia, Facultad de Ciencias, Universidad Nacional de Colombia, Carrera 30 # 45-01, Bogota; Colombia; (M.M.F.); (G.D.)
| | - Gabriela Delgado
- Grupo de Investigación en Inmunotoxicología, Departamento de Farmacia, Facultad de Ciencias, Universidad Nacional de Colombia, Carrera 30 # 45-01, Bogota; Colombia; (M.M.F.); (G.D.)
| | - Fanny Guzmán
- Núcleo de Biotecnología Curauma (NBC), Pontificia Universidad Católica de Valparaiso, Avenida Universidad 2373223, Curauma, Valparaiso-Chile;
| | - Paulino Gómez-Puertas
- Grupo de Modelado Molecular del Centro de Biología Molecular Severo Ochoa, Microbes in Health and Welfare Department, Universidad Autónoma de Madrid (CBMSO, CSIC-UAM), 28049 Madrid, Spain;
| | - José María Requena
- Grupo Regulación de la Expresión Génica en Leishmania del Centro de Biología Molecular Severo Ochoa, Molecular Biology Department, Universidad Autónoma de Madrid (CBMSO, CSIC-UAM), 28049 Madrid, Spain;
| | - Concepción J. Puerta
- Grupo de Investigación en Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 # 40- 62, Bogotá, Colombia; (E.R.-M.); (C.A.R.); (E.R.R.)
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Wild K, Becker MM, Kempf G, Sinning I. Structure, dynamics and interactions of large SRP variants. Biol Chem 2019; 401:63-80. [DOI: 10.1515/hsz-2019-0282] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/09/2019] [Indexed: 12/11/2022]
Abstract
Abstract
Co-translational protein targeting to membranes relies on the signal recognition particle (SRP) system consisting of a cytosolic ribonucleoprotein complex and its membrane-associated receptor. SRP recognizes N-terminal cleavable signals or signal anchor sequences, retards translation, and delivers ribosome-nascent chain complexes (RNCs) to vacant translocation channels in the target membrane. While our mechanistic understanding is well advanced for the small bacterial systems it lags behind for the large bacterial, archaeal and eukaryotic SRP variants including an Alu and an S domain. Here we describe recent advances on structural and functional insights in domain architecture, particle dynamics and interplay with RNCs and translocon and GTP-dependent regulation of co-translational protein targeting stimulated by SRP RNA.
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Affiliation(s)
- Klemens Wild
- Heidelberg University Biochemistry Center (BZH) , INF 328 , D-69120 Heidelberg , Germany
| | - Matthias M.M. Becker
- Heidelberg University Biochemistry Center (BZH) , INF 328 , D-69120 Heidelberg , Germany
| | - Georg Kempf
- Heidelberg University Biochemistry Center (BZH) , INF 328 , D-69120 Heidelberg , Germany
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH) , INF 328 , D-69120 Heidelberg , Germany
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Pohlschroder M, Pfeiffer F, Schulze S, Abdul Halim MF. Archaeal cell surface biogenesis. FEMS Microbiol Rev 2018; 42:694-717. [PMID: 29912330 PMCID: PMC6098224 DOI: 10.1093/femsre/fuy027] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/12/2018] [Indexed: 12/13/2022] Open
Abstract
Cell surfaces are critical for diverse functions across all domains of life, from cell-cell communication and nutrient uptake to cell stability and surface attachment. While certain aspects of the mechanisms supporting the biosynthesis of the archaeal cell surface are unique, likely due to important differences in cell surface compositions between domains, others are shared with bacteria or eukaryotes or both. Based on recent studies completed on a phylogenetically diverse array of archaea, from a wide variety of habitats, here we discuss advances in the characterization of mechanisms underpinning archaeal cell surface biogenesis. These include those facilitating co- and post-translational protein targeting to the cell surface, transport into and across the archaeal lipid membrane, and protein anchoring strategies. We also discuss, in some detail, the assembly of specific cell surface structures, such as the archaeal S-layer and the type IV pili. We will highlight the importance of post-translational protein modifications, such as lipid attachment and glycosylation, in the biosynthesis as well as the regulation of the functions of these cell surface structures and present the differences and similarities in the biogenesis of type IV pili across prokaryotic domains.
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Affiliation(s)
| | - Friedhelm Pfeiffer
- Computational Biology Group, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Stefan Schulze
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Abstract
All organisms must adapt to ever-changing environmental conditions and accordingly have evolved diverse signal transduction systems. In bacteria, the most abundant networks are built around the two-component signal transduction systems that include histidine kinases and receiver domains. In contrast, eukaryotic signal transduction is dominated by serine/threonine/tyrosine protein kinases. Both of these systems are also found in archaea, but they are not as common and diversified as their bacterial and eukaryotic counterparts, suggesting the possibility that archaea have evolved other, still uncharacterized signal transduction networks. Here we propose a role for KaiC family ATPases, known to be key components of the circadian clock in cyanobacteria, in archaeal signal transduction. The KaiC family is notably expanded in most archaeal genomes, and although most of these ATPases remain poorly characterized, members of the KaiC family have been shown to control archaellum assembly and have been found to be a stable component of the gas vesicle system in Halobacteria Computational analyses described here suggest that KaiC-like ATPases and their homologues with inactivated ATPase domains are involved in many other archaeal signal transduction pathways and comprise major hubs of complex regulatory networks. We predict numerous input and output domains that are linked to KaiC-like proteins, including putative homologues of eukaryotic DEATH domains that could function as adapters in archaeal signaling networks. We further address the relationships of the archaeal family of KaiC homologues to the bona fide KaiC of cyanobacteria and implications for the existence of a KaiC-based circadian clock apparatus in archaea.IMPORTANCE Little is currently known about signal transduction pathways in Archaea Recent studies indicate that KaiC-like ATPases, known as key components of the circadian clock apparatus in cyanobacteria, are involved in the regulation of archaellum assembly and, likely, type IV pili and the gas vesicle system in Archaea We performed comprehensive comparative genomic analyses of the KaiC family. A vast protein interaction network was revealed, with KaiC family proteins as hubs for numerous input and output components, many of which are shared with two-component signal transduction systems. Putative KaiC-based signal transduction systems are predicted to regulate the activities of membrane-associated complexes and individual proteins, such as signal recognition particle and membrane transporters, and also could be important for oxidative stress response regulation. KaiC-centered signal transduction networks are predicted to play major roles in archaeal physiology, and this work is expected to stimulate their experimental characterization.
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Gupta S, Roy M, Ghosh A. The Archaeal Signal Recognition Particle: Present Understanding and Future Perspective. Curr Microbiol 2016; 74:284-297. [DOI: 10.1007/s00284-016-1167-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 11/21/2016] [Indexed: 10/20/2022]
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Wild K, Bange G, Motiejunas D, Kribelbauer J, Hendricks A, Segnitz B, Wade RC, Sinning I. Structural Basis for Conserved Regulation and Adaptation of the Signal Recognition Particle Targeting Complex. J Mol Biol 2016; 428:2880-97. [PMID: 27241309 DOI: 10.1016/j.jmb.2016.05.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/13/2016] [Accepted: 05/18/2016] [Indexed: 12/25/2022]
Abstract
The signal recognition particle (SRP) is a ribonucleoprotein complex with a key role in targeting and insertion of membrane proteins. The two SRP GTPases, SRP54 (Ffh in bacteria) and FtsY (SRα in eukaryotes), form the core of the targeting complex (TC) regulating the SRP cycle. The architecture of the TC and its stimulation by RNA has been described for the bacterial SRP system while this information is lacking for other domains of life. Here, we present the crystal structures of the GTPase heterodimers of archaeal (Sulfolobus solfataricus), eukaryotic (Homo sapiens), and chloroplast (Arabidopsis thaliana) SRP systems. The comprehensive structural comparison combined with Brownian dynamics simulations of TC formation allows for the description of the general blueprint and of specific adaptations of the quasi-symmetric heterodimer. Our work defines conserved external nucleotide-binding sites for SRP GTPase activation by RNA. Structural analyses of the GDP-bound, post-hydrolysis states reveal a conserved, magnesium-sensitive switch within the I-box. Overall, we provide a general model for SRP cycle regulation by RNA.
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Affiliation(s)
- Klemens Wild
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Gert Bange
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Domantas Motiejunas
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg, Germany
| | - Judith Kribelbauer
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Astrid Hendricks
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Bernd Segnitz
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Rebecca C Wade
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg, Germany; Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, INF 282, 69120 Heidelberg, Germany
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany.
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Fernández-Boo S, Villalba A, Cao A. Variable protein profiles in extracellular products of the protistan parasite Perkinsus olseni among regions of the Spanish coast. J Invertebr Pathol 2015; 132:233-241. [DOI: 10.1016/j.jip.2015.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 11/02/2015] [Accepted: 11/06/2015] [Indexed: 10/22/2022]
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Pathways of colicin import: utilization of BtuB, OmpF porin and the TolC drug-export protein. Biochem Soc Trans 2012; 40:1463-8. [PMID: 23176499 DOI: 10.1042/bst20120211] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pathway I. Group A nuclease colicins parasitize and bind tightly (Kd ≤ 10−9 M) to the vitamin B12 receptor on which they diffuse laterally in the OM (outer membrane) and use their long (≥100 Å; 1 Å=0.1 nm) receptor-binding domain as a ‘fishing pole’ to locate the OmpF porin channel for translocation. Crystal structures of OmpF imply that a disordered N-terminal segment of the colicin T-domain initiates insertion. Pathway II. Colicin N does not possess a ‘fishing pole’ receptor-binding domain. Instead, it uses OmpF as the Omp (outer membrane protein) for reception and translocation, processes in which LPS (lipopolysaccharide) may also serve. Keio collection experiments defined the LPS core that is used. Pathway III. Colicin E1 utilizes the drug-export protein TolC for import. CD spectra and thermal-melting analysis predict: (i) N-terminal translocation (T) and central receptor (BtuB) -binding (R) domains are predominantly α-helical; and (ii) helical coiled-coil conformation of the R-domain is similar to that of colicins E3 and Ia. Recombinant colicin peptides spanning the N-terminal translocation domain defined TolC-binding site(s). The N-terminal 40-residue segment lacks the ordered secondary structure. Peptide 41–190 is helical (78%), co-elutes with TolC and occluded TolC channels. Driven by a trans-negative potential, peptides 82–140 and 141–190 occluded TolC channels. The use of TolC for colicin E1 import implies that the interaction of this colicin with the other Tol proteins does not occur in the periplasmic space, but rather through Tol domains in the cytoplasmic membrane, thus explaining colicin E1 cytotoxicity towards a strain in which a 234 residue periplasmic TolA segment is deleted.
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Braig D, Mircheva M, Sachelaru I, van der Sluis EO, Sturm L, Beckmann R, Koch HG. Signal sequence-independent SRP-SR complex formation at the membrane suggests an alternative targeting pathway within the SRP cycle. Mol Biol Cell 2011; 22:2309-23. [PMID: 21551068 PMCID: PMC3128533 DOI: 10.1091/mbc.e11-02-0152] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Our study reveals an alternative route in the SRP-dependent protein targeting pathway that includes a preassembled, membrane-bound SRP-SR complex. This alternative route is fully sufficient to maintain cell viability in the absence of a soluble SRP. Protein targeting by the signal recognition particle (SRP) and the bacterial SRP receptor FtsY requires a series of closely coordinated steps that monitor the presence of a substrate, the membrane, and a vacant translocon. Although the influence of substrate binding on FtsY-SRP complex formation is well documented, the contribution of the membrane is largely unknown. In the current study, we found that negatively charged phospholipids stimulate FtsY-SRP complex formation. Phospholipids act on a conserved positively charged amphipathic helix in FtsY and induce a conformational change that strongly enhances the FtsY-lipid interaction. This membrane-bound, signal sequence–independent FtsY-SRP complex is able to recruit RNCs to the membrane and to transfer them to the Sec translocon. Significantly, the same results were also observed with an artificial FtsY-SRP fusion protein, which was tethered to the membrane via a transmembrane domain. This indicates that substrate recognition by a soluble SRP is not essential for cotranslational targeting in Escherichia coli. Our findings reveal a remarkable flexibility of SRP-dependent protein targeting, as they indicate that substrate recognition can occur either in the cytosol via ribosome-bound SRP or at the membrane via a preassembled FtsY-SRP complex.
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Affiliation(s)
- David Braig
- Institut für Biochemie und Molekularbiologie, ZBMZ, 79104 Freiburg, Germany
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Lateral opening of a translocon upon entry of protein suggests the mechanism of insertion into membranes. Proc Natl Acad Sci U S A 2010; 107:17182-7. [PMID: 20855604 DOI: 10.1073/pnas.1012556107] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The structure of the protein-translocating channel SecYEβ from Pyrococcus furiosus at 3.1-Å resolution suggests a mechanism for chaperoning transmembrane regions of a protein substrate during its lateral delivery into the lipid bilayer. Cytoplasmic segments of SecY orient the C-terminal α-helical region of another molecule, suggesting a general binding mode and a promiscuous guiding surface capable of accommodating diverse nascent chains at the exit of the ribosomal tunnel. To accommodate this putative nascent chain mimic, the cytoplasmic vestibule widens, and a lateral exit portal is opened throughout its entire length for partition of transmembrane helical segments to the lipid bilayer. In this primed channel, the central plug still occludes the pore while the lateral gate is opened, enabling topological arbitration during early protein insertion. In vivo, a 15 amino acid truncation of the cytoplasmic C-terminal helix of SecY fails to rescue a secY-deficient strain, supporting the essential role of this helix as suggested from the structure.
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Bibi E. Early targeting events during membrane protein biogenesis in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:841-50. [PMID: 20682283 DOI: 10.1016/j.bbamem.2010.07.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2010] [Revised: 07/21/2010] [Accepted: 07/22/2010] [Indexed: 10/19/2022]
Abstract
All living cells have co-translational pathways for targeting membrane proteins. Co-translation pathways for secretory proteins also exist but mostly in eukaryotes. Unlike secretory proteins, the biosynthetic pathway of most membrane proteins is conserved through evolution and these proteins are usually synthesized by membrane-bound ribosomes. Translation on the membrane requires that both the ribosomes and the mRNAs be properly localized. Theoretically, this can be achieved by several means. (i) The current view is that the targeting of cytosolic mRNA-ribosome-nascent chain complexes (RNCs) to the membrane is initiated by information in the emerging hydrophobic nascent polypeptides. (ii) The alternative model suggests that ribosomes may be targeted to the membrane also constitutively, whereas the appropriate mRNAs may be carried on small ribosomal subunits or targeted by other cellular factors to the membrane-bound ribosomes. Importantly, the available experimental data do not rule out the possibility that cells may also utilize both pathways in parallel. In any case, it is well documented that a major player in the targeting pathway is the signal recognition particle (SRP) system composed of the SRP and its receptor (SR). Although the functional core of the SRP system is evolutionarily conserved, its composition and biological practice come with different flavors in various organisms. This review is dedicated mainly to the Escherichia (E.) coli SRP, where the biochemical and structural properties of components of the SRP system have been relatively characterized, yielding essential information about various aspects of the pathway. In addition, several cellular interactions of the SRP and its receptor have been described in E. coli, providing insights into their spatial function. Collectively, these in vitro studies have led to the current view of the targeting pathway [see (i) above]. Interestingly, however, in vivo studies of the role of the SRP and its receptor, with emphasis on the temporal progress of the pathway, elicited an alternative hypothesis [see (ii) above]. This article is part of a Special Issue entitled Protein translocation across or insertion into membranes.
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Affiliation(s)
- Eitan Bibi
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
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Archaea signal recognition particle shows the way. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2010; 2010:485051. [PMID: 20672053 PMCID: PMC2905702 DOI: 10.1155/2010/485051] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 05/14/2010] [Indexed: 01/24/2023]
Abstract
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.
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14
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Hartman H, Smith TF. GTPases and the origin of the ribosome. Biol Direct 2010; 5:36. [PMID: 20487556 PMCID: PMC2881122 DOI: 10.1186/1745-6150-5-36] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 05/20/2010] [Indexed: 11/17/2022] Open
Abstract
Background This paper is an attempt to trace the evolution of the ribosome through the evolution of the universal P-loop GTPases that are involved with the ribosome in translation and with the attachment of the ribosome to the membrane. The GTPases involved in translation in Bacteria/Archaea are the elongation factors EFTu/EF1, the initiation factors IF2/aeIF5b + aeIF2, and the elongation factors EFG/EF2. All of these GTPases also contain the OB fold also found in the non GTPase IF1 involved in initiation. The GTPase involved in the signal recognition particle in most Bacteria and Archaea is SRP54. Results 1) The Elongation Factors of the Archaea based on structural considerations of the domains have the following evolutionary path: EF1→ aeIF2 → EF2. The evolution of the aeIF5b was a later event; 2) the Elongation Factors of the Bacteria based on the topological considerations of the GTPase domain have a similar evolutionary path: EFTu→ IF→2→EFG. These evolutionary sequences reflect the evolution of the LSU followed by the SSU to form the ribosome; 3) the OB-fold IF1 is a mimic of an ancient tRNA minihelix. Conclusion The evolution of translational GTPases of both the Archaea and Bacteria point to the evolution of the ribosome. The elongation factors, EFTu/EF1, began as a Ras-like GTPase bringing the activated minihelix tRNA to the Large Subunit Unit. The initiation factors and elongation factor would then have evolved from the EFTu/EF1 as the small subunit was added to the evolving ribosome. The SRP has an SRP54 GTPase and a specific RNA fold in its RNA component similar to the PTC. We consider the SRP to be a remnant of an ancient form of an LSU bound to a membrane. Reviewers This article was reviewed by George Fox, Leonid Mirny and Chris Sander.
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Affiliation(s)
- Hyman Hartman
- BioMolecular Engineering Research Center, Boston University, 36 Cummington Street, Boston, MA 02215, USA
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15
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Calo D, Eichler J. Crossing the membrane in Archaea, the third domain of life. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:885-91. [PMID: 20347718 DOI: 10.1016/j.bbamem.2010.03.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 03/18/2010] [Accepted: 03/18/2010] [Indexed: 11/16/2022]
Abstract
Many of the recent advancements in the field of protein translocation, particularly from the structural perspective, have relied on Archaea. For instance, the solved structures of the translocon from the methanoarchaeon Methanocaldococcus jannaschii of the ribosomal large subunit from the haloarchaeon Haloarcula marismortui and of components of the SRP pathway from several archaeal species have provided novel insight into various aspects of the translocation event. Given the major contribution that Archaea have made to our understanding of how proteins enter and traverse membranes, it is surprising that relatively little is known of protein translocation in Archaea in comparison to the well-defined translocation pathways of Eukarya and Bacteria. What is known, however, points to archaeal translocation as comprising a mosaic of eukaryal and bacterial traits together with aspects of the process seemingly unique to this, the third domain of life. Here, current understanding of archaeal protein translocation is considered. This article is part of a Special Issue entitled Protein translocation across or insertion into membranes.
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Affiliation(s)
- Doron Calo
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheva 84105, Israel
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Yuan J, Zweers JC, van Dijl JM, Dalbey RE. Protein transport across and into cell membranes in bacteria and archaea. Cell Mol Life Sci 2010; 67:179-99. [PMID: 19823765 PMCID: PMC11115550 DOI: 10.1007/s00018-009-0160-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 09/13/2009] [Accepted: 09/21/2009] [Indexed: 12/21/2022]
Abstract
In the three domains of life, the Sec, YidC/Oxa1, and Tat translocases play important roles in protein translocation across membranes and membrane protein insertion. While extensive studies have been performed on the endoplasmic reticular and Escherichia coli systems, far fewer studies have been done on archaea, other Gram-negative bacteria, and Gram-positive bacteria. Interestingly, work carried out to date has shown that there are differences in the protein transport systems in terms of the number of translocase components and, in some cases, the translocation mechanisms and energy sources that drive translocation. In this review, we will describe the different systems employed to translocate and insert proteins across or into the cytoplasmic membrane of archaea and bacteria.
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Affiliation(s)
- Jijun Yuan
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210 USA
| | - Jessica C. Zweers
- Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, 30001, 9700 RB Groningen, The Netherlands
| | - Jan Maarten van Dijl
- Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, 30001, 9700 RB Groningen, The Netherlands
| | - Ross E. Dalbey
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210 USA
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Mircheva M, Boy D, Weiche B, Hucke F, Graumann P, Koch HG. Predominant membrane localization is an essential feature of the bacterial signal recognition particle receptor. BMC Biol 2009; 7:76. [PMID: 19912622 PMCID: PMC2780400 DOI: 10.1186/1741-7007-7-76] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 11/13/2009] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND The signal recognition particle (SRP) receptor plays a vital role in co-translational protein targeting, because it connects the soluble SRP-ribosome-nascent chain complex (SRP-RNCs) to the membrane bound Sec translocon. The eukaryotic SRP receptor (SR) is a heterodimeric protein complex, consisting of two unrelated GTPases. The SRbeta subunit is an integral membrane protein, which tethers the SRP-interacting SRalpha subunit permanently to the endoplasmic reticulum membrane. The prokaryotic SR lacks the SRbeta subunit and consists of only the SRalpha homologue FtsY. Strikingly, although FtsY requires membrane contact for functionality, cell fractionation studies have localized FtsY predominantly to the cytosolic fraction of Escherichia coli. So far, the exact function of the soluble SR in E. coli is unknown, but it has been suggested that, in contrast to eukaryotes, the prokaryotic SR might bind SRP-RNCs already in the cytosol and only then initiates membrane targeting. RESULTS In the current study we have determined the contribution of soluble FtsY to co-translational targeting in vitro and have re-analysed the localization of FtsY in vivo by fluorescence microscopy. Our data show that FtsY can bind to SRP-ribosome nascent chains (RNCs) in the absence of membranes. However, these soluble FtsY-SRP-RNC complexes are not efficiently targeted to the membrane. In contrast, we observed effective targeting of SRP-RNCs to membrane-bond FtsY. These data show that soluble FtsY does not contribute significantly to cotranslational targeting in E. coli. In agreement with this observation, our in vivo analyses of FtsY localization in bacterial cells by fluorescence microscopy revealed that the vast majority of FtsY was localized to the inner membrane and that soluble FtsY constituted only a negligible species in vivo. CONCLUSION The exact function of the SRP receptor (SR) in bacteria has so far been enigmatic. Our data show that the bacterial SR is almost exclusively membrane-bound in vivo, indicating that the presence of a soluble SR is probably an artefact of cell fractionation. Thus, co-translational targeting in bacteria does not involve the formation of a soluble SR-signal recognition particle (SRP)-ribosome nascent chain (RNC) intermediate but requires membrane contact of FtsY for efficient SRP-RNC recruitment.
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Affiliation(s)
- Miryana Mircheva
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany.
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18
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Marty NJ, Rajalingam D, Kight AD, Lewis NE, Fologea D, Kumar TKS, Henry RL, Goforth RL. The membrane-binding motif of the chloroplast signal recognition particle receptor (cpFtsY) regulates GTPase activity. J Biol Chem 2009; 284:14891-903. [PMID: 19293157 PMCID: PMC2685671 DOI: 10.1074/jbc.m900775200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 03/16/2009] [Indexed: 11/06/2022] Open
Abstract
The chloroplast signal recognition particle (cpSRP) and its receptor (cpFtsY) function in thylakoid biogenesis to target integral membrane proteins to thylakoids. Unlike cytosolic SRP receptors in eukaryotes, cpFtsY partitions between thylakoid membranes and the soluble stroma. Based on sequence alignments, a membrane-binding motif identified in Escherichia coli FtsY appears to be conserved in cpFtsY, yet whether the proposed motif is responsible for the membrane-binding function of cpFtsY has yet to be shown experimentally. Our studies show that a small N-terminal region in cpFtsY stabilizes a membrane interaction critical to cpFtsY function in cpSRP-dependent protein targeting. This membrane-binding motif is both necessary and sufficient to direct cpFtsY and fused passenger proteins to thylakoids. Our results demonstrate that the cpFtsY membrane-binding motif may be functionally replaced by the corresponding region from E. coli, confirming that the membrane-binding motif is conserved among organellar and prokaryotic homologs. Furthermore, the capacity of cpFtsY for lipid binding correlates with liposome-induced GTP hydrolysis stimulation. Mutations that debilitate the membrane-binding motif in cpFtsY result in higher rates of GTP hydrolysis, suggesting that negative regulation is provided by the intact membrane-binding region in the absence of a bilayer. Furthermore, NMR and CD structural studies of the N-terminal region and the analogous region in the E. coli SRP receptor revealed a conformational change in secondary structure that takes place upon lipid binding. These studies suggest that the cpFtsY membrane-binding motif plays a critical role in the intramolecular communication that regulates cpSRP receptor functions at the membrane.
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Affiliation(s)
- Naomi J Marty
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, USA
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Braig D, Bär C, Thumfart JO, Koch HG. Two cooperating helices constitute the lipid-binding domain of the bacterial SRP receptor. J Mol Biol 2009; 390:401-13. [PMID: 19414018 DOI: 10.1016/j.jmb.2009.04.061] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 04/02/2009] [Accepted: 04/28/2009] [Indexed: 11/19/2022]
Abstract
Protein targeting by the bacterial signal recognition particle requires the specific interaction of the signal recognition particle (SRP)-ribosome-nascent chain complex with FtsY, the bacterial SRP receptor. Although FtsY in Escherichia coli lacks a transmembrane domain, the membrane-bound FtsY displays many features of an integral membrane protein. Our data reveal that it is the cooperative action of two lipid-binding helices that allows this unusually strong membrane contact. Helix I comprises the first 14 amino acids of FtsY and the second is located at the interface between the A- and the N-domain of FtsY. We show by site-directed cross-linking and binding assays that both helices bind to negatively charged phospholipids, with a preference for phosphatidyl glycerol. Despite the strong lipid binding, helix I does not seem to be completely inserted into the lipid phase, but appears to be oriented parallel with the membrane surface. The two helices together with the connecting linker constitute an independently folded domain, which maintains its lipid binding even in the absence of the conserved NG-core of FtsY. In summary, our data reveal that the two consecutive lipid-binding helices of FtsY can provide a membrane contact that does not differ significantly in stability from that provided by a transmembrane domain. This explains why the bacterial SRP receptor does not require an integral beta-subunit for membrane binding.
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Affiliation(s)
- David Braig
- Institut für Biochemie und Molekularbiologie, ZBMZ, Albert-Ludwigs-Universität Freiburg, Germany
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