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Pinheiro L, Freitas M, Branco PS. Phosphate-Containing Glycolipids: A Review on Synthesis and Bioactivity. ChemMedChem 2024:e202400315. [PMID: 39031174 DOI: 10.1002/cmdc.202400315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 07/18/2024] [Accepted: 07/18/2024] [Indexed: 07/22/2024]
Abstract
Phosphate-containing glycolipids (PcGL) are scarcer than the better understood glycolipids. They are composed of arrangements of phosphate, carbohydrates and glycerol units and are always found associated with lipids. PcGL are often found associated with cell membranes, suggesting they play roles in cell membrane structure and intercellular interactions. This article aims to provide an up-to-date overview of the existing knowledge and research on PcGL, emphasizing their synthesis and wide range of biological activities. When it comes to the synthesis of PcGL compounds, the strategies for glycosylation mainly rely on the thioglycoside donor, the trichloroacetamidate donor and halide donor strategies, while phosphorylation is stapled and falls on either phosphite chemistry or phosphoryl chloride chemistry. Certain bacteria utilize PcGLs in their pathogenicity, triggering an inflammatory response within the host's defense mechanisms. The best-known examples of these structures are teichoic acids, lipopolysaccharide and the capsular polysaccharide found in bacteria, all of which are frequently implicated in bacterial infections. Given the degree of variability within PcGL structures, they were found to display a wide range of bioactivities. PcGL compounds were found to: (1) have anti-metastatic properties, (2) behave as agonists or antagonists of platelet aggregation, (3) be mostly pro-inflammatory, (4) display antifungal and antibiotic activity and (5) have neurogenic activity.
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Affiliation(s)
- Luís Pinheiro
- Department of Chemistry, NOVA School of Science and Technology, LAQV-REQUIMTE, Campus da Caparica, 2825-149, Caparica, Portugal
| | - Marisa Freitas
- Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, LAQV-REQUIMTE, Faculty of Pharmacy, University of Porto, 4050-313, Porto, Portugal
| | - Paula S Branco
- Department of Chemistry, NOVA School of Science and Technology, LAQV-REQUIMTE, Campus da Caparica, 2825-149, Caparica, Portugal
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2
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Mori S, Shionyu M, Shimamoto K, Nomura K. Bacterial Glycolipid Acting on Protein Transport Across Membranes. Chembiochem 2024; 25:e202300808. [PMID: 38400776 DOI: 10.1002/cbic.202300808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/11/2024] [Accepted: 02/22/2024] [Indexed: 02/26/2024]
Abstract
The process of protein transport across membranes involves a variety of factors and has been extensively investigated. Traditionally, proteinaceous translocons and chaperones have been recognized as crucial factors in this process. However, recent studies have highlighted the significant roles played by lipids and a glycolipid present in biological membranes in membrane protein transport. Membrane lipids can influence transport efficiency by altering the physicochemical properties of membranes. Notably, our studies have revealed that diacylglycerol (DAG) attenuates mobility in the membrane core region, leading to a dramatic suppression of membrane protein integration. Conversely, a glycolipid in Escherichia coli inner membranes, named membrane protein integrase (MPIase), enhances integration not only through the alteration of membrane properties but also via direct interactions with membrane proteins. This review explores the mechanisms of membrane protein integration mediated by membrane lipids, specifically DAG, and MPIase. Our results, along with the employed physicochemical analysis methods such as fluorescence measurements, nuclear magnetic resonance, surface plasmon resonance, and docking simulation, are presented to elucidate these mechanisms.
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Affiliation(s)
- Shoko Mori
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan
| | - Masafumi Shionyu
- Department of Frontier Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga, 526-0829, Japan
| | - Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan
- Department of Chemistry Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Kaoru Nomura
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan
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3
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Nomura K, Mori S, Shimamoto K. Roles of a Glycolipid MPIase in Sec-Independent Membrane Protein Insertion. MEMBRANES 2024; 14:48. [PMID: 38392675 PMCID: PMC10890265 DOI: 10.3390/membranes14020048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 02/24/2024]
Abstract
Membrane protein integrase (MPIase), an endogenous glycolipid in Escherichia coli (E. coli) membranes, is essential for membrane protein insertion in E. coli. We have examined Sec-independent membrane protein insertion mechanisms facilitated by MPIase using physicochemical analytical techniques, namely solid-state nuclear magnetic resonance, fluorescence measurements, and surface plasmon resonance. In this review, we outline the physicochemical characteristics of membranes that may affect membrane insertion of proteins. Subsequently, we introduce our results verifying the effects of membrane lipids on insertion and estimate the impact of MPIase. Although MPIase is a minor component of E. coli membranes, it regulates insertion by altering the physicochemical properties of the membrane. In addition, MPIase promotes insertion by interacting with substrate proteins. We propose comprehensive mechanisms for the membrane insertion of proteins involving MPIase, which provide a physicochemical basis for understanding the roles of glycolipids in protein translocation.
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Affiliation(s)
- Kaoru Nomura
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Shoko Mori
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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4
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Osawa T, Fujikawa K, Shimamoto K. Structures, functions, and syntheses of glycero-glycophospholipids. Front Chem 2024; 12:1353688. [PMID: 38389730 PMCID: PMC10881803 DOI: 10.3389/fchem.2024.1353688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 01/24/2024] [Indexed: 02/24/2024] Open
Abstract
Biological membranes consist of integral and peripheral protein-associated lipid bilayers. Although constituent lipids vary among cells, membrane lipids are mainly classified as phospholipids, glycolipids, and sterols. Phospholipids are further divided into glycerophospholipids and sphingophospholipids, whereas glycolipids are further classified as glyceroglycolipids and sphingoglycolipids. Both glycerophospholipids and glyceroglycolipids contain diacylglycerol as the common backbone, but their head groups differ. Most glycerolipids have polar head groups containing phosphate esters or sugar moieties. However, trace components termed glycero-glycophospholipids, each possessing both a phosphate ester and a sugar moiety, exist in membranes. Recently, the unique biological activities of glycero-glycophospholipids have attracted considerable attention. In this review, we describe the structure, distribution, function, biosynthesis, and chemical synthetic approaches of representative glycero-glycophospholipids-phosphatidylglucoside (PtdGlc) and enterobacterial common antigen (ECA). In addition, we introduce our recent studies on the rare glycero-glyco"pyrophospho"lipid, membrane protein integrase (MPIase), which is involved in protein translocation across biomembranes.
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Affiliation(s)
- Tsukiho Osawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
| | - Kohki Fujikawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
| | - Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan
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5
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den Uijl MJ, Driessen AJM. Phospholipid dependency of membrane protein insertion by the Sec translocon. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184232. [PMID: 37734458 DOI: 10.1016/j.bbamem.2023.184232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 09/08/2023] [Accepted: 09/14/2023] [Indexed: 09/23/2023]
Abstract
Membrane protein insertion into and translocation across the bacterial cytoplasmic membrane are essential processes facilitated by the Sec translocon. Membrane insertion occurs co-translationally whereby the ribosome nascent chain is targeted to the translocon via signal recognition particle and its receptor FtsY. The phospholipid dependence of membrane protein insertion has remained mostly unknown. Here we assessed in vitro the dependence of the SecA independent insertion of the mannitol permease MtlA into the membrane on the main phospholipid species present in Escherichia coli. We observed that insertion depends on the presence of phosphatidylglycerol and is due to the anionic nature of the polar headgroup, while insertion is stimulated by the zwitterionic phosphatidylethanolamine. We found an optimal insertion efficiency at about 30 mol% DOPG and 50 mol% DOPE which approaches the bulk membrane phospholipid composition of E. coli.
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Affiliation(s)
- Max J den Uijl
- University of Groningen, Groningen Biomolecular Sciences and Biotechnology, 9747 AG Groningen, the Netherlands
| | - Arnold J M Driessen
- University of Groningen, Groningen Biomolecular Sciences and Biotechnology, 9747 AG Groningen, the Netherlands.
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6
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Shimamoto K, Fujikawa K, Osawa T, Mori S, Nomura K, Nishiyama KI. Key contributions of a glycolipid to membrane protein integration. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2024; 100:387-413. [PMID: 39085064 DOI: 10.2183/pjab.100.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
Regulation of membrane protein integration involves molecular devices such as Sec-translocons or the insertase YidC. We have identified an integration-promoting factor in the inner membrane of Escherichia coli called membrane protein integrase (MPIase). Structural analysis revealed that, despite its enzyme-like name, MPIase is a glycolipid with a long glycan comprising N-acetyl amino sugars, a pyrophosphate linker, and a diacylglycerol (DAG) anchor. Additionally, we found that DAG, a minor membrane component, blocks spontaneous integration. In this review, we demonstrate how they contribute to Sec-independent membrane protein integration in bacteria using a comprehensive approach including synthetic chemistry and biophysical analyses. DAG blocks unfavorable spontaneous integrations by suppressing mobility in the membrane core, whereas MPIase compensates for this. Moreover, MPIase plays critical roles in capturing a substrate protein to prevent its aggregation, attracting it to the membrane surface, facilitating its insertion into the membrane, and delivering it to other factors. The combination of DAG and MPIase efficiently regulates the integration of membrane proteins.
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Affiliation(s)
- Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Soraku-gun, Kyoto, Japan
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Kohki Fujikawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Soraku-gun, Kyoto, Japan
| | - Tsukiho Osawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Soraku-gun, Kyoto, Japan
| | - Shoko Mori
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Soraku-gun, Kyoto, Japan
| | - Kaoru Nomura
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Soraku-gun, Kyoto, Japan
| | - Ken-Ichi Nishiyama
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan
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7
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Phosphatidylglycerol Is the Lipid Donor for Synthesis of Phospholipid-Linked Enterobacterial Common Antigen. J Bacteriol 2023; 205:e0040322. [PMID: 36622229 PMCID: PMC9879101 DOI: 10.1128/jb.00403-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The Gram-negative outer membrane (OM) is an asymmetric bilayer with phospholipids in its inner leaflet and mainly lipopolysaccharide (LPS) in its outer leaflet and is largely impermeable to many antibiotics. In Enterobacterales (e.g., Escherichia, Salmonella, Klebsiella, and Yersinia), the outer leaflet of the OM also contains phosphoglyceride-linked enterobacterial common antigen (ECAPG). This molecule consists of the conserved ECA carbohydrate linked to diacylglycerol-phosphate (DAG-P) through a phosphodiester bond. ECAPG contributes to the OM permeability barrier and modeling suggests that it may alter the packing of LPS molecules in the OM. Here, we investigate, in Escherichia coli K-12, the reaction synthesizing ECAPG from ECA precursor linked to an isoprenoid carrier to identify the lipid donor that provides the DAG-P moiety to ECAPG. Through overexpression of phospholipid biosynthesis genes, we observed alterations expected to increase levels of phosphatidylglycerol (PG) increased the synthesis of ECAPG, whereas alterations expected to decrease levels of PG decreased the synthesis of ECAPG. We discovered depletion of PG levels in strains that could synthesize ECAPG, but not other forms of ECA, causes additional growth defects, likely due to the buildup of ECA precursor on the isoprenoid carrier inhibiting peptidoglycan biosynthesis. Our results demonstrate ECAPG can be synthesized in the absence of the other major phospholipids (phosphatidylethanolamine and cardiolipin). Overall, these results conclusively demonstrate PG is the lipid donor for the synthesis of ECAPG and provide a key insight into the reaction producing ECAPG. In addition, these results provide an interesting parallel to lipoprotein acylation, which also uses PG as its DAG donor. IMPORTANCE The Gram-negative outer membrane is a permeability barrier preventing cellular entry of antibiotics. However, outer membrane biogenesis pathways are targets for small molecule development. Here, we investigate the synthesis of a form of enterobacterial common antigen (ECA), ECAPG, found in the outer membrane of Enterobacterales (e.g., Escherichia, Salmonella, and Klebsiella). ECAPG consists of the conserved ECA carbohydrate unit linked to diacylglycerol-phosphate-ECA is a phospholipid headgroup. The details of the reaction forming this molecule from polymerized ECA precursor are unknown. We determined the lipid donor providing the phospholipid moiety is phosphatidylglycerol. Understanding the synthesis of outer membrane constituents such as ECAPG provides the opportunity for development of molecules to increase outer membrane permeability, expanding the antibiotics available to treat Gram-negative infections.
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Kamemoto Y, Hikage R, Han Y, Sekiya Y, Sawasato K, Nishiyama KI. Coordinated upregulation of two CDP-diacylglycerol synthases, YnbB and CdsA, is essential for cell growth and membrane protein export in the cold. FEMS Microbiol Lett 2023; 370:fnad131. [PMID: 38070879 DOI: 10.1093/femsle/fnad131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 12/04/2023] [Accepted: 12/08/2023] [Indexed: 12/29/2023] Open
Abstract
YnbB is a paralogue of CdsA, a CDP-diacylglycerol synthase. While the cdsA gene is essential, the ynbB gene is dispensable. So far, no phenotype of ynbB knockout has been observed. We found that a ynbB knockout strain acquired cold-sensitivity on growth under CdsA-limited conditions. We found that MPIase, a glycolipid involved in protein export, is cold-upregulated to facilitate protein export in the cold, by increasing the mRNA levels of not only CdsA but also that of YnbB. Under non-permissive conditions, phospholipid biosynthesis proceeded normally, however, MPIase upregulation was inhibited with accumulation of precursors of membrane and secretory proteins such as M13 procoat and proOmpA, indicating that YnbB is dedicated to MPIase biosynthesis, complementing the CdsA function.
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Affiliation(s)
- Yuki Kamemoto
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Runa Hikage
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Youjung Han
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Yusei Sekiya
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Katsuhiro Sawasato
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Ken-Ichi Nishiyama
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
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9
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Nishikawa H, Sawasato K, Mori S, Fujikawa K, Nomura K, Shimamoto K, Nishiyama KI. Interaction between glycolipid MPIase and proteinaceous factors during protein integration into the cytoplasmic membrane of E. coli. Front Mol Biosci 2022; 9:986602. [PMID: 36060260 PMCID: PMC9437254 DOI: 10.3389/fmolb.2022.986602] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 07/22/2022] [Indexed: 11/13/2022] Open
Abstract
Protein integration into biomembranes is an essential biological phenomenon common to all organisms. While various factors involved in protein integration, such as SRP, SecYEG and YidC, are proteinaceous, we identified a glycolipid named MPIase (Membrane Protein Integrase), which is present in the cytoplasmic membrane of E. coli. In vitro experiments using inverted membrane vesicles prepared from MPIase-depleted strains, and liposomes containing MPIase showed that MPIase is required for insertion of a subset of membrane proteins, which has been thought to be SecYEG-independent and YidC-dependent. Also, SecYEG-dependent substrate membrane proteins require MPIase in addition. Furthermore, MPIase is also essential for insertion of proteins with multiple negative charges, which requires both YidC and the proton motive force (PMF). MPIase directly interacts with SecYEG and YidC on the membrane. MPIase not only cooperates with these factors but also has a molecular chaperone-like function specific to the substrate membrane proteins through direct interaction with the glycan chain. Thus, MPIase catalyzes membrane insertion by accepting nascent membrane proteins on the membrane through its chaperone-like function, i.e., direct interaction with the substrate proteins, and then MPIase functionally interacts with SecYEG and YidC for substrate delivery, and acts with PMF to facilitate and complete membrane insertion when necessary. In this review, we will outline the mechanisms underlying membrane insertion catalyzed by MPIase, which cooperates with proteinaceous factors and PMF.
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Affiliation(s)
- Hanako Nishikawa
- Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Katsuhiro Sawasato
- Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Shoko Mori
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
| | - Kohki Fujikawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
| | - Kaoru Nomura
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
| | - Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
| | - Ken-Ichi Nishiyama
- Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan
- *Correspondence: Ken-Ichi Nishiyama,
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10
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Role of a bacterial glycolipid in Sec-independent membrane protein insertion. Sci Rep 2022; 12:12231. [PMID: 35851412 PMCID: PMC9293918 DOI: 10.1038/s41598-022-16304-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 07/07/2022] [Indexed: 11/08/2022] Open
Abstract
Non-proteinaceous components in membranes regulate membrane protein insertion cooperatively with proteinaceous translocons. An endogenous glycolipid in the Escherichia coli membrane called membrane protein integrase (MPIase) is one such component. Here, we focused on the Sec translocon-independent pathway and examined the mechanisms of MPIase-facilitated protein insertion using physicochemical techniques. We determined the membrane insertion efficiency of a small hydrophobic protein using solid-state nuclear magnetic resonance, which showed good agreement with that determined by the insertion assay using an in vitro translation system. The observed insertion efficiency was strongly correlated with membrane physicochemical properties measured using fluorescence techniques. Diacylglycerol, a trace component of E. coli membrane, reduced the acyl chain mobility in the core region and inhibited the insertion, whereas MPIase restored them. We observed the electrostatic intermolecular interactions between MPIase and the side chain of basic amino acids in the protein, suggesting that the negatively charged pyrophosphate of MPIase attracts the positively charged residues of a protein near the membrane surface, which triggers the insertion. Thus, this study demonstrated the ingenious approach of MPIase to support membrane insertion of proteins by using its unique molecular structure in various ways.
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11
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Shimane Y, Kuruma Y. Rapid and Facile Preparation of Giant Vesicles by the Droplet Transfer Method for Artificial Cell Construction. Front Bioeng Biotechnol 2022; 10:873854. [PMID: 35464723 PMCID: PMC9021372 DOI: 10.3389/fbioe.2022.873854] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/03/2022] [Indexed: 11/22/2022] Open
Abstract
Giant vesicles have been widely used for the bottom-up construction of artificial (or synthetic) cells and the physicochemical analysis of lipid membranes. Although methods for the formation of giant vesicles and the encapsulation of molecules within them have been established, a standardized protocol has not been shared among researchers including non-experts. Here we proposed a rapid and facile protocol that allows the formation of giant vesicles within 30 min. The quality of the giant vesicles encapsulating a cell-free protein expression system was comparable to that of the ones formed using a conventional method, in terms of the synthesis of both soluble and membrane proteins. We also performed protein synthesis in artificial cells using a lyophilized cell-free mixture and showed an equivalent level of protein synthesis. Our method could become a standard method for giant vesicle formation suited for artificial cell research.
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Affiliation(s)
- Yasuhiro Shimane
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
- Research Institute of Industrial Technology, Toyo University, Saitama, Japan
| | - Yutetsu Kuruma
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
- PRESTO, Japan Science and Technology Agency (JST), Saitama, Japan
- Graduate School of Nanobioscience, Yokohama City University, Yokohama, Japan
- *Correspondence: Yutetsu Kuruma,
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12
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Mori S, Nomura K, Fujikawa K, Osawa T, Shionyu M, Yoda T, Shirai T, Tsuda S, Yoshizawa-Kumagaye K, Masuda S, Nishio H, Yoshiya T, Suzuki S, Muramoto M, Nishiyama KI, Shimamoto K. Intermolecular Interactions between a Membrane Protein and a Glycolipid Essential for Membrane Protein Integration. ACS Chem Biol 2022; 17:609-618. [PMID: 35239308 DOI: 10.1021/acschembio.1c00882] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Inducing newly synthesized proteins to appropriate locations is an indispensable biological function in every organism. Integration of proteins into biomembranes in Escherichia coli is mediated by proteinaceous factors, such as Sec translocons and an insertase YidC. Additionally, a glycolipid named MPIase (membrane protein integrase), composed of a long sugar chain and pyrophospholipid, was proven essential for membrane protein integration. We reported that a synthesized minimal unit of MPIase possessing only one trisaccharide, mini-MPIase-3, involves an essential structure for the integration activity. Here, to elucidate integration mechanisms using MPIase, we analyzed intermolecular interactions of MPIase or its synthetic analogs with a model substrate, the Pf3 coat protein, using physicochemical methods. Surface plasmon resonance (SPR) analyses revealed the importance of a pyrophosphate for affinity to the Pf3 coat protein. Compared with mini-MPIase-3, natural MPIase showed faster association and dissociation due to its long sugar chain despite the slight difference in affinity. To focus on more detailed MPIase substructures, we performed docking simulations and saturation transfer difference-nuclear magnetic resonance. These experiments yielded that the 6-O-acetyl group on glucosamine and the phosphate of MPIase play important roles leading to interactions with the Pf3 coat protein. The high affinity of MPIase to the hydrophobic region and the basic amino acid residues of the protein was suggested by docking simulations and proven experimentally by SPR using protein mutants devoid of target regions. These results demonstrated the direct interactions of MPIase with a substrate protein and revealed detailed mechanisms of membrane protein integration.
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Affiliation(s)
- Shoko Mori
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Kaoru Nomura
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Kohki Fujikawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Tsukiho Osawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Masafumi Shionyu
- Department of Frontier Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga 526-0829, Japan
| | - Takao Yoda
- Department of Frontier Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga 526-0829, Japan
| | - Tsuyoshi Shirai
- Department of Frontier Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga 526-0829, Japan
| | - Shugo Tsuda
- Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Kumiko Yoshizawa-Kumagaye
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Shun Masuda
- Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Hideki Nishio
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Taku Yoshiya
- Peptide Institute, Inc., 7-2-9 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Sonomi Suzuki
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan
| | - Maki Muramoto
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan
| | - Ken-ichi Nishiyama
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan
| | - Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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13
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Inhibition of SRP-dependent protein secretion by the bacterial alarmone (p)ppGpp. Nat Commun 2022; 13:1069. [PMID: 35217658 PMCID: PMC8881573 DOI: 10.1038/s41467-022-28675-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 02/07/2022] [Indexed: 11/08/2022] Open
Abstract
The stringent response enables bacteria to respond to nutrient limitation and other stress conditions through production of the nucleotide-based second messengers ppGpp and pppGpp, collectively known as (p)ppGpp. Here, we report that (p)ppGpp inhibits the signal recognition particle (SRP)-dependent protein targeting pathway, which is essential for membrane protein biogenesis and protein secretion. More specifically, (p)ppGpp binds to the SRP GTPases Ffh and FtsY, and inhibits the formation of the SRP receptor-targeting complex, which is central for the coordinated binding of the translating ribosome to the SecYEG translocon. Cryo-EM analysis of SRP bound to translating ribosomes suggests that (p)ppGpp may induce a distinct conformational stabilization of the NG domain of Ffh and FtsY in Bacillus subtilis but not in E. coli. Bacterial responses to nutrient limitation and other stress conditions are often modulated by the nucleotide-based second messenger (p)ppGpp. Here, the authors show that (p)ppGpp inhibits the SRP membrane-protein insertion and secretion pathway by binding to GTPases Ffh and FtsY.
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14
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Fujikawa K, Mori S, Nishiyama KI, Shimamoto K. A bacterial glycolipid essential for membrane protein integration. Adv Carbohydr Chem Biochem 2022; 81:95-129. [DOI: 10.1016/bs.accb.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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15
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Endo Y, Shimizu Y, Nishikawa H, Sawasato K, Nishiyama KI. Interplay between MPIase, YidC, and PMF during Sec-independent insertion of membrane proteins. Life Sci Alliance 2021; 5:5/1/e202101162. [PMID: 34642230 PMCID: PMC8548208 DOI: 10.26508/lsa.202101162] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 11/24/2022] Open
Abstract
Charges in the N-terminal region and the synthesis level of membrane proteins with N-out topology determine YidC and PMF dependencies with the interplay between glycolipid MPIase, YidC, and PMF. Integral membrane proteins with the N-out topology are inserted into membranes usually in YidC- and PMF-dependent manners. The molecular basis of the various dependencies on insertion factors is not fully understood. A model protein, Pf3-Lep, is inserted independently of both YidC and PMF, whereas the V15D mutant requires both YidC and PMF in vivo. We analyzed the mechanisms that determine the insertion factor dependency in vitro. Glycolipid MPIase was required for insertion of both proteins because MPIase depletion caused a significant defect in insertion. On the other hand, YidC depletion and PMF dissipation had no effects on Pf3-Lep insertion, whereas V15D insertion was reduced. We reconstituted (proteo)liposomes containing MPIase, YidC, and/or F0F1-ATPase. MPIase was essential for insertion of both proteins. YidC and PMF stimulated Pf3-Lep insertion as the synthesis level increased. V15D insertion was stimulated by both YidC and PMF irrespective of the synthesis level. These results indicate that charges in the N-terminal region and the synthesis level are the determinants of YidC and PMF dependencies with the interplay between MPIase, YidC, and PMF.
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Affiliation(s)
- Yuta Endo
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan
| | - Yuko Shimizu
- Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Hanako Nishikawa
- Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Katsuhiro Sawasato
- Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Ken-Ichi Nishiyama
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan .,Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan
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16
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Sekiya Y, Sawasato K, Nishiyama KI. Expression of Cds4/5 of Arabidopsis chloroplasts in E. coli reveals the membrane topology of the C-terminal region of CDP-diacylglycerol synthases. Genes Cells 2021; 26:727-738. [PMID: 34166546 DOI: 10.1111/gtc.12880] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 06/21/2021] [Accepted: 06/21/2021] [Indexed: 11/30/2022]
Abstract
CDP-diacylglycerol synthases (Cds) are conserved from bacteria to eukaryotes. Bacterial CdsA is involved not only in phospholipid biosynthesis but also in biosynthesis of glycolipid MPIase, an essential glycolipid that catalyzes membrane protein integration. We found that both Cds4 and Cds5 of Arabidopsis chloroplasts complement cdsA knockout by supporting both phospholipid and MPIase biosyntheses. Comparison of the sequences of CdsA and Cds4/5 suggests a difference in membrane topology at the C-termini, since the region assigned as the last transmembrane region of CdsA, which follows the conserved cytoplasmic domain, is missing in Cds4/5. Deletion of the C-terminal region abolished the function, indicating the importance of the region. Both 6 × His tag attachment to CdsA and substitution of the C-terminal 6 residues with 6 × His did not affect the function. These 6 × His tags were sensitive to protease added from the cytosolic side in vitro, indicating that this region is not a transmembrane one but forms a membrane-embedded reentrant loop. Thus, the C-terminal region of Cds homologues forms a reentrant loop, of which structure is important for the Cds function.
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Affiliation(s)
- Yusei Sekiya
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Katsuhiro Sawasato
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Ken-Ichi Nishiyama
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Japan
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17
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Nishikawa H, Kanno K, Endo Y, Nishiyama KI. Ring assembly of c subunits of F 0 F 1 -ATP synthase in Propionigenium modestum requires YidC and UncI following MPIase-dependent membrane insertion. FEBS Lett 2021; 595:647-654. [PMID: 33423295 DOI: 10.1002/1873-3468.14036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/20/2020] [Accepted: 12/31/2020] [Indexed: 01/25/2023]
Abstract
The c subunits of F0 F1 -ATP synthase (F0 c) assemble into a ring structure, following membrane insertion that is dependent on both glycolipid MPIase and protein YidC. We analyzed the insertion and assembly processes of Propionigenium modestum F0 c (Pm-F0 c), of which the ring structure is resistant to SDS. Ring assembly of Pm-F0 c requires P. modestum UncI (Pm-UncI). Ring assembly of in vitro synthesized Pm-F0 c was observed when both YidC and Pm-UncI were reconstituted into liposomes of Escherichia coli phospholipids. Under the physiological conditions where spontaneous insertion had been blocked by diacylglycerol, MPIase was necessary for Pm-F0 c insertion allowing the subsequent YidC/Pm-UncI-dependent ring assembly. Thus, we have succeeded in the complete reconstitution of membrane insertion and subsequent ring assembly of Pm-F0 c.
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Affiliation(s)
- Hanako Nishikawa
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan
| | - Kotoka Kanno
- Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Yuta Endo
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan
| | - Ken-Ichi Nishiyama
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan.,Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan
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18
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Steinberg R, Origi A, Natriashvili A, Sarmah P, Licheva M, Walker PM, Kraft C, High S, Luirink J, Shi WQ, Helmstädter M, Ulbrich MH, Koch HG. Posttranslational insertion of small membrane proteins by the bacterial signal recognition particle. PLoS Biol 2020; 18:e3000874. [PMID: 32997663 PMCID: PMC7549839 DOI: 10.1371/journal.pbio.3000874] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 10/12/2020] [Accepted: 09/02/2020] [Indexed: 01/05/2023] Open
Abstract
Small membrane proteins represent a largely unexplored yet abundant class of proteins in pro- and eukaryotes. They essentially consist of a single transmembrane domain and are associated with stress response mechanisms in bacteria. How these proteins are inserted into the bacterial membrane is unknown. Our study revealed that in Escherichia coli, the 27-amino-acid-long model protein YohP is recognized by the signal recognition particle (SRP), as indicated by in vivo and in vitro site-directed cross-linking. Cross-links to SRP were also observed for a second small membrane protein, the 33-amino-acid-long YkgR. However, in contrast to the canonical cotranslational recognition by SRP, SRP was found to bind to YohP posttranslationally. In vitro protein transport assays in the presence of a SecY inhibitor and proteoliposome studies demonstrated that SRP and its receptor FtsY are essential for the posttranslational membrane insertion of YohP by either the SecYEG translocon or by the YidC insertase. Furthermore, our data showed that the yohP mRNA localized preferentially and translation-independently to the bacterial membrane in vivo. In summary, our data revealed that YohP engages an unique SRP-dependent posttranslational insertion pathway that is likely preceded by an mRNA targeting step. This further highlights the enormous plasticity of bacterial protein transport machineries. Small membrane proteins represent a largely unexplored yet abundant class of proteins, but how they are inserted into the bacterial membrane is unknown. This study identifies a novel posttranslational protein transport pathway that relies on the signal recognition particle and the SecYEG translocon/YidC insertase.
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Affiliation(s)
- Ruth Steinberg
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Andrea Origi
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Ana Natriashvili
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Pinku Sarmah
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Mariya Licheva
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Princess M. Walker
- Department of Chemistry, Ball State University, Muncie, Indiana, United States of America
| | - Claudine Kraft
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Stephen High
- School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Joen Luirink
- Molecular Microbiology, AIMMS, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Wei. Q. Shi
- Department of Chemistry, Ball State University, Muncie, Indiana, United States of America
| | - Martin Helmstädter
- Internal Medicine IV, Department of Medicine, Medical Center − University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Maximilian H. Ulbrich
- Internal Medicine IV, Department of Medicine, Medical Center − University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Hans-Georg Koch
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
- * E-mail:
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19
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Nishikawa H, Sasaki M, Nishiyama KI. In vitro Assay for Bacterial Membrane Protein Integration into Proteoliposomes. Bio Protoc 2020; 10:e3626. [PMID: 33659299 DOI: 10.21769/bioprotoc.3626] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/25/2020] [Accepted: 03/26/2020] [Indexed: 11/02/2022] Open
Abstract
It is important to experimentally determine how membrane proteins are integrated into biomembranes to unveil the roles of the integration factors, and to understand the functions and structures of membrane proteins. We have developed a reconstitution system for membrane protein integration in E. coli using purified factors, in which the integration reaction in vivo is highly reproducible. This system enabled not only analysis of membrane-embedded factors including glycolipid MPIase, but also elucidation of the detailed mechanisms underlying membrane protein integration. Using the system, the integration of membrane proteins can be evaluated in vitro through a protease-protection assay. We report here how to prepare (proteo)liposomes and to determine the activities of membrane protein integration.
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Affiliation(s)
- Hanako Nishikawa
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan
| | - Masaru Sasaki
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan
| | - Ken-Ichi Nishiyama
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan.,Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Japan
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20
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Kamemoto Y, Funaba N, Kawakami M, Sawasato K, Kanno K, Suzuki S, Nishikawa H, Sato R, Nishiyama KI. Biosynthesis of glycolipid MPIase (membrane protein integrase) is independent of the genes for ECA (enterobacterial common antigen). J GEN APPL MICROBIOL 2020; 66:169-174. [DOI: 10.2323/jgam.2019.05.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Yuki Kamemoto
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University
| | - Nanaka Funaba
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University
| | - Mayu Kawakami
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University
| | | | - Kotoka Kanno
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University
| | - Sonomi Suzuki
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University
| | - Hanako Nishikawa
- The United Graduate School of Agricultural Sciences, Iwate University
| | - Ryo Sato
- The United Graduate School of Agricultural Sciences, Iwate University
| | - Ken-ichi Nishiyama
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University
- The United Graduate School of Agricultural Sciences, Iwate University
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21
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Fujikawa K, Nomura K, Nishiyama KI, Shimamoto K. Novel Glycolipid Involved in Membrane Protein Integration: Structure and Mode of Action. J SYN ORG CHEM JPN 2019. [DOI: 10.5059/yukigoseikyokaishi.77.1096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Kohki Fujikawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences
| | - Kaoru Nomura
- Bioorganic Research Institute, Suntory Foundation for Life Sciences
| | - Ken-ichi Nishiyama
- Department of Biological Chemistry, Faculty of Agriculture, Iwate University
| | - Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences
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22
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Sasaki M, Nishikawa H, Suzuki S, Moser M, Huber M, Sawasato K, Matsubayashi HT, Kumazaki K, Tsukazaki T, Kuruma Y, Nureki O, Ueda T, Nishiyama KI. The bacterial protein YidC accelerates MPIase-dependent integration of membrane proteins. J Biol Chem 2019; 294:18898-18908. [PMID: 31662434 DOI: 10.1074/jbc.ra119.011248] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/25/2019] [Indexed: 01/06/2023] Open
Abstract
Bacterial membrane proteins are integrated into membranes through the concerted activities of a series of integration factors, including membrane protein integrase (MPIase). However, how MPIase activity is complemented by other integration factors during membrane protein integration is incompletely understood. Here, using inverted inner-membrane vesicle and reconstituted (proteo)liposome preparations from Escherichia coli cells, along with membrane protein integration assays and the PURE system to produce membrane proteins, we found that anti-MPIase IgG inhibits the integration of both the Sec-independent substrate 3L-Pf3 coat and the Sec-dependent substrate MtlA into E. coli membrane vesicles. MPIase-depleted membrane vesicles lacked both 3L-Pf3 coat and MtlA integration, indicating that MPIase is involved in the integration of both proteins. We developed a reconstitution system in which disordered spontaneous integration was precluded, which revealed that SecYEG, YidC, or both, are not sufficient for Sec-dependent and -independent integration. Although YidC had no effect on MPIase-dependent integration of Sec-independent substrates in the conventional assay system, YidC significantly accelerated the integration when the substrate amounts were increased in our PURE system-based assay. Similar acceleration by YidC was observed for MtlA integration. YidC mutants with amino acid substitutions in the hydrophilic cavity inside the membrane were defective in the acceleration of the Sec-independent integration. Of note, MPIase was up-regulated upon YidC depletion. These results indicate that YidC accelerates the MPIase-dependent integration of membrane proteins, suggesting that MPIase and YidC function sequentially and cooperatively during the catalytic cycle of membrane protein integration.
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Affiliation(s)
- Masaru Sasaki
- United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Hanako Nishikawa
- United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Sonomi Suzuki
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Michael Moser
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Maria Huber
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Katsuhiro Sawasato
- United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Hideaki T Matsubayashi
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Kaoru Kumazaki
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | | | - Yutetsu Kuruma
- Earth-Life Science Institute, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8550, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Takuya Ueda
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Ken-Ichi Nishiyama
- United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan; Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan; Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan.
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23
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Sawasato K, Sekiya Y, Nishiyama K. Two‐step induction ofcdsApromoters leads to upregulation of the glycolipidMPIase at cold temperature. FEBS Lett 2019; 593:1711-1723. [DOI: 10.1002/1873-3468.13460] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 05/16/2019] [Accepted: 05/21/2019] [Indexed: 11/07/2022]
Affiliation(s)
- Katsuhiro Sawasato
- The United Graduate School of Agricultural Sciences Iwate University Morioka Japan
| | - Yusei Sekiya
- Department of Biological Chemistry and Food Science Faculty of Agriculture Iwate University Morioka Japan
| | - Ken‐ichi Nishiyama
- The United Graduate School of Agricultural Sciences Iwate University Morioka Japan
- Department of Biological Chemistry and Food Science Faculty of Agriculture Iwate University Morioka Japan
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24
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Nomura K, Yamaguchi T, Mori S, Fujikawa K, Nishiyama KI, Shimanouchi T, Tanimoto Y, Morigaki K, Shimamoto K. Alteration of Membrane Physicochemical Properties by Two Factors for Membrane Protein Integration. Biophys J 2019; 117:99-110. [PMID: 31164197 PMCID: PMC6626835 DOI: 10.1016/j.bpj.2019.05.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 05/08/2019] [Accepted: 05/14/2019] [Indexed: 12/01/2022] Open
Abstract
After a nascent chain of a membrane protein emerges from the ribosomal tunnel, the protein is integrated into the cell membrane. This process is controlled by a series of proteinaceous molecular devices, such as signal recognition particles and Sec translocons. In addition to these proteins, we discovered two endogenous components regulating membrane protein integration in the inner membrane of Escherichia coli. The integration is blocked by diacylglycerol (DAG), whereas the blocking is relieved by a glycolipid named membrane protein integrase (MPIase). Here, we investigated the influence of these integration-blocking and integration-promoting factors on the physicochemical properties of membrane lipids via solid-state NMR and fluorescence measurements. These factors did not have destructive effects on membrane morphology because the membrane maintained its lamellar structure and did not fuse in the presence of DAG and/or MPIase at their effective concentrations. We next focused on membrane flexibility. DAG did not affect the mobility of the membrane surface, whereas the sugar chain in MPIase was highly mobile and enhanced the flexibility of membrane lipid headgroups. Comparison with a synthetic MPIase analog revealed the effects of the long sugar chain on membrane properties. The acyl chain order inside the membrane was increased by DAG, whereas the increase was cancelled by the addition of MPIase. MPIase also loosened the membrane lipid packing. Focusing on the transbilayer movement, MPIase reduced the rapid flip-flop motion of DAG. On the other hand, MPIase could not compensate for the diminished lateral diffusion by DAG. These results suggest that by manipulating the membrane lipids dynamics, DAG inhibits the protein from contacting the inner membrane, whereas the flexible long sugar chain of MPIase increases the opportunity for interaction between the membrane and the protein, leading to membrane integration of the newly formed protein.
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Affiliation(s)
- Kaoru Nomura
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan.
| | - Toshiyuki Yamaguchi
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
| | - Shoko Mori
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
| | - Kohki Fujikawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan
| | - Ken-Ichi Nishiyama
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan
| | | | - Yasushi Tanimoto
- Graduate School of Agricultural Science, Kobe University, Kobe, Japan
| | | | - Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan.
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25
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Sawasato K, Suzuki S, Nishiyama KI. Increased expression of the bacterial glycolipid MPIase is required for efficient protein translocation across membranes in cold conditions. J Biol Chem 2019; 294:8403-8411. [PMID: 30936205 DOI: 10.1074/jbc.ra119.008457] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 03/21/2019] [Indexed: 12/21/2022] Open
Abstract
Protein integration into and translocation across biological membranes are vital events for organismal survival and are fundamentally conserved among many organisms. Membrane protein integrase (MPIase) is a glycolipid that drives membrane protein integration into the cytoplasmic membrane in Escherichia coli MPIase also stimulates protein translocation across the membrane, but how its expression is regulated is incompletely understood. In this study, we found that the expression level of MPIase significantly increases in the cold (<25 °C), whereas that of the SecYEG translocon does not. Using previously created gene-knockout E. coli strains, we also found that either the cdsA or ynbB gene, both encoding rate-limiting enzymes for MPIase biosynthesis, is responsible for the increase in the MPIase expression. Furthermore, using pulse-chase experiments and protein integration assays, we demonstrated that the increase in MPIase levels is important for efficient protein translocation, but not for protein integration. We conclude that MPIase expression is required to stimulate protein translocation in cold conditions and is controlled by cdsA and ynbB gene expression.
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Affiliation(s)
- Katsuhiro Sawasato
- United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Sonomi Suzuki
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Ken-Ichi Nishiyama
- United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan; Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan.
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26
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Sato R, Sawasato K, Nishiyama KI. YnbB is a CdsA paralogue dedicated to biosynthesis of glycolipid MPIase involved in membrane protein integration. Biochem Biophys Res Commun 2019; 510:636-642. [DOI: 10.1016/j.bbrc.2019.01.145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 01/31/2019] [Indexed: 10/27/2022]
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Sawasato K, Sato R, Nishikawa H, Iimura N, Kamemoto Y, Fujikawa K, Yamaguchi T, Kuruma Y, Tamura Y, Endo T, Ueda T, Shimamoto K, Nishiyama KI. CdsA is involved in biosynthesis of glycolipid MPIase essential for membrane protein integration in vivo. Sci Rep 2019; 9:1372. [PMID: 30718729 PMCID: PMC6362211 DOI: 10.1038/s41598-018-37809-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 12/07/2018] [Indexed: 11/17/2022] Open
Abstract
MPIase is a glycolipid that is involved in membrane protein integration. Despite evaluation of its functions in vitro, the lack of information on MPIase biosynthesis hampered verification of its involvement in vivo. In this study, we found that depletion of CdsA, a CDP-diacylglycerol synthase, caused not only a defect in phospholipid biosynthesis but also MPIase depletion with accumulation of the precursors of both membrane protein M13 coat protein and secretory protein OmpA. Yeast Tam41p, a mitochondrial CDP-diacylglycerol synthase, suppressed the defect in phospholipid biosynthesis, but restored neither MPIase biosynthesis, precursor processing, nor cell growth, indicating that MPIase is essential for membrane protein integration and therefore for cell growth. Consistently, we observed a severe defect in protein integration into MPIase-depleted membrane vesicles in vitro. Thus, the function of MPIase as a factor involved in protein integration was proven in vivo as well as in vitro. Moreover, Cds1p, a eukaryotic CdsA homologue, showed a potential for MPIase biosynthesis. From these results, we speculate the presence of a eukaryotic MPIase homologue.
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Affiliation(s)
- Katsuhiro Sawasato
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate, 020-8550, Japan
| | - Ryo Sato
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate, 020-8550, Japan
| | - Hanako Nishikawa
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate, 020-8550, Japan
| | - Naoki Iimura
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Iwate, 020-8550, Japan
| | - Yuki Kamemoto
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Iwate, 020-8550, Japan
| | - Kohki Fujikawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Kyoto, 619-0284, Japan
| | - Toshiyuki Yamaguchi
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Kyoto, 619-0284, Japan
| | - Yutetsu Kuruma
- Earth-Life Science Institute, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8550, Japan
| | - Yasushi Tamura
- Faculty of Science, Yamagata University, Yamagata, Yamagata, 990-8560, Japan
| | - Toshiya Endo
- Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto, 603-8555, Japan
| | - Takuya Ueda
- Department of Computational Biology and Medical Sciences Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, 277-8562, Japan
| | - Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Kyoto, 619-0284, Japan
| | - Ken-Ichi Nishiyama
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate, 020-8550, Japan. .,Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Iwate, 020-8550, Japan. .,Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Iwate, 020-8550, Japan.
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Fujikawa K, Suzuki S, Nagase R, Ikeda S, Mori S, Nomura K, Nishiyama KI, Shimamoto K. Syntheses and Activities of the Functional Structures of a Glycolipid Essential for Membrane Protein Integration. ACS Chem Biol 2018; 13:2719-2727. [PMID: 30064209 DOI: 10.1021/acschembio.8b00654] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
MPIase is the first known glycolipid that is essential for membrane protein integration in the inner membrane of E. coli. Since the amount of natural MPIase available for analysis is limited and it contains structural heterogeneity, precisely designed synthetic derivatives are promising tools for further elucidation of its membrane protein integration mechanism. Thus, we synthesized the minimal unit of MPIase, a trisaccharyl pyrophospholipid termed mini-MPIase-3, and its derivatives. Integration assays revealed that the chemically synthesized trisaccharyl pyrophospholipid possesses significant activity, indicating that it includes the essential structure for membrane integration. Structure-activity relationship studies demonstrated that the number of trisaccharide units and the 6- O-acetyl group on N-acetylglucosamine contribute to efficient integration. Furthermore, anchoring in the membrane by a lipid moiety was essential for the integration. However, the addition of phosphorylated glycans devoid of the lipid moiety in the assay solution modulated the integration activity of MPIase embedded in liposomes, suggesting an interaction between phosphorylated glycans and substrate proteins in aqueous solutions. The prevention of protein aggregation required the 6- O-acetyl group on N-acetylglucosamine, a phosphate group at the reducing end of the glycan, and a long glycan chain. Taken together, we verified the mechanism of the initial step of the translocon-independent pathway in which a membrane protein is captured by a glycan of MPIase, which maintains its structure to be competent for integration, and then MPIase integrates it into the membrane by hydrophobic interactions with membrane lipids.
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Affiliation(s)
- Kohki Fujikawa
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Sonomi Suzuki
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan
| | - Ryohei Nagase
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Shiori Ikeda
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan
| | - Shoko Mori
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Kaoru Nomura
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Ken-ichi Nishiyama
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan
| | - Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
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Lu M, Zhao X, Xing H, Xun Z, Yang T, Cai C, Wang D, Ding P. Liposome-chaperoned cell-free synthesis for the design of proteoliposomes: Implications for therapeutic delivery. Acta Biomater 2018; 76:1-20. [PMID: 29625253 DOI: 10.1016/j.actbio.2018.03.043] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 03/20/2018] [Accepted: 03/27/2018] [Indexed: 12/12/2022]
Abstract
Cell-free (CF) protein synthesis has emerged as a powerful technique platform for efficient protein production in vitro. Liposomes have been widely studied as therapeutic carriers due to their biocompatibility, biodegradability, low toxicity, flexible surface manipulation, easy preparation, and higher cargo encapsulation capability. However, rapid immune clearance, insufficient targeting capacity, and poor cytoplasmic delivery efficiency substantially restrict their clinical application. The incorporation of functional membrane proteins (MPs) or peptides allows the transfer of biological properties to liposomes and imparts them with improved circulation, increased targeting, and efficient intracellular delivery. Liposome-chaperoned CF synthesis enables production of proteoliposomes in one-step reaction, which not only substantially simplifies the production procedure but also keeps protein functionality intact. Building off these observations, proteoliposomes with integrated MPs represent an excellent candidate for therapeutic delivery. In this review, we describe recent advances in CF synthesis with emphasis on detailing key factors for improving CF expression efficiency. Furthermore, we provide insights into strategies for rational design of proteoliposomal nanodelivery systems via CF synthesis. STATEMENT OF SIGNIFICANCE Liposome-chaperoned CF synthesis has emerged as a powerful approach for the design of recombinant proteoliposomes in one-step reaction. The incorporation of bioactive MPs or peptides into liposomes via CF synthesis can facilitate the development of proteoliposomal nanodelivery systems with improved circulation, increased targeting, and enhanced cellular delivery capacity. Moreover, by adapting lessons learned from natural delivery vehicles, novel bio-inspired proteoliposomes with enhanced delivery properties could be produced in CF systems. In this review, we first give an overview of CF synthesis with focus on enhancing protein expression in liposome-chaperoned CF systems. Furthermore, we intend to provide insight into harnessing CF-synthesized proteoliposomes for efficient therapeutic delivery.
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Nakamura S, Suzuki S, Saito H, Nishiyama KI. Cholesterol blocks spontaneous insertion of membrane proteins into liposomes of phosphatidylcholine. J Biochem 2017; 163:313-319. [DOI: 10.1093/jb/mvx083] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 10/20/2017] [Indexed: 02/01/2023] Open
Affiliation(s)
- Shota Nakamura
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, 020-8550 Iwate, Japan
| | - Sonomi Suzuki
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, 020-8550 Iwate, Japan
| | - Hiroaki Saito
- RIKEN Quantitative Biology Center, Suita, 565-0874 Osaka, Japan
| | - Ken-ichi Nishiyama
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, 020-8550 Iwate, Japan
- Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, 020-8550 Iwate, Japan
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Nishikawa H, Sasaki M, Nishiyama KI. Membrane insertion of F 0 c subunit of F 0F 1 ATPase depends on glycolipozyme MPIase and is stimulated by YidC. Biochem Biophys Res Commun 2017; 487:477-482. [PMID: 28431927 DOI: 10.1016/j.bbrc.2017.04.095] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 04/07/2017] [Indexed: 01/04/2023]
Abstract
The F0 c subunit of F0F1 ATPase (F0-c) possesses two membrane-spanning stretches with N- and C-termini exposed to the periplasmic (extracellular) side of the cytoplasmic membrane of E. coli. Although F0-c insertion has been extensively analyzed in vitro by means of protease protection assaying, it is unclear whether such assays allow elucidation of the insertion process faithfully, since the membrane-protected fragment, an index of membrane insertion, is a full-length polypeptide of F0-c, which is the same as the protease-resistant conformation without membrane insertion. We found that the protease-resistant conformation could be discriminated from membrane-insertion by including octyl glucoside on protease digestion. By means of this system, we found that F0-c insertion depends on MPIase, a glycolipozyme involved in membrane insertion, and is stimulated by YidC. In addition, we found that acidic phospholipids PG and CL transform F0-c into a protease-resistant form, while MPIase prevents the acquisition of such a protease-resistant conformation.
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Affiliation(s)
- Hanako Nishikawa
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Masaru Sasaki
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Ken-Ichi Nishiyama
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka, Japan; Department of Biological Chemistry and Food Science, Faculty of Agriculture, Iwate University, Morioka, Japan.
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Shimamoto K. Elucidation of Excitatory Neurotransmission and Membrane Protein Integration Mechanisms. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2016. [DOI: 10.1246/bcsj.20150336] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Keiko Shimamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences
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33
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Abstract
The large-scale production of recombinant G protein-coupled receptors (GPCRs) is one of the major bottlenecks that hamper functional and structural studies of this important class of integral membrane proteins. Heterologous overexpression of GPCRs often results in low yields of active protein, usually due to a combination of several factors, such as low expression levels, protein insolubility, host cell toxicity, and the need to use harsh and often denaturing detergents (e.g., SDS, LDAO, OG, and DDM, among others) to extract the recombinant receptor from the host cell membrane. Many of these problematic issues are inherently linked to cell-based expression systems and can therefore be circumvented by the use of cell-free systems. In this unit, we provide a range of protocols for the production of GPCRs in a cell-free expression system. Using this system, we typically obtain GPCR expression levels of ∼1 mg per ml of reaction mixture in the continuous-exchange configuration. Although the protocols in this unit have been optimized for the cell-free expression of GPCRs, they should provide a good starting point for the production of other classes of membrane proteins, such as ion channels, aquaporins, carrier proteins, membrane-bound enzymes, and even large molecular complexes.
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Affiliation(s)
- Kenneth Segers
- VIB Center for the Biology of Disease, Flanders Institute for Biotechnology (VIB), Leuven, Belgium.,Structural Biology Group, Biologics Research Europe, Janssen Research & Development, Beerse, Belgium
| | - Stefan Masure
- Structural Biology Group, Biologics Research Europe, Janssen Research & Development, Beerse, Belgium
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Soga H, Fujii S, Yomo T, Kato Y, Watanabe H, Matsuura T. In vitro membrane protein synthesis inside cell-sized vesicles reveals the dependence of membrane protein integration on vesicle volume. ACS Synth Biol 2014; 3:372-9. [PMID: 24328098 DOI: 10.1021/sb400094c] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Giant unilamellar vesicles (GUVs) are vesicles>1 μm in diameter that provide an environment in which the effect of a confined reaction volume on intravesicular reactions can be investigated. By synthesizing EmrE, a multidrug transporter from Escherichia coli, as a model membrane protein using a reconstituted in vitro transcription-translation system inside GUVs, we investigated the effect of a confined volume on the synthesis and membrane integration of EmrE. Flow cytometry was used to analyze multiple properties of the vesicles and to quantify EmrE synthesis inside GUVs composed of only 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. We found that EmrE was synthesized and integrated into the GUV membrane in its active form. We also found that the ratio of membrane-integrated EmrE to total synthesized EmrE increased with decreasing vesicle volume; this finding is explained by the effect of an increased surface-area-to-volume ratio in smaller vesicles. In vitro membrane synthesis inside GUVs is a useful approach to study quantitatively the properties of membrane proteins and their interaction with the membrane under cell-mimicking environments.
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Affiliation(s)
- Haruka Soga
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita, Osaka, Japan
| | - Satoshi Fujii
- Exploratory
Research for Advanced Technology, Japan Science and Technology Agency, 1-5 Yamadaoka, Suita, Osaka, Japan
| | - Tetsuya Yomo
- Exploratory
Research for Advanced Technology, Japan Science and Technology Agency, 1-5 Yamadaoka, Suita, Osaka, Japan
- Department
of Bioinformatic Engineering, Graduate School of Information Science
and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, Japan
| | - Yasuhiko Kato
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita, Osaka, Japan
| | - Hajime Watanabe
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita, Osaka, Japan
| | - Tomoaki Matsuura
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita, Osaka, Japan
- Exploratory
Research for Advanced Technology, Japan Science and Technology Agency, 1-5 Yamadaoka, Suita, Osaka, Japan
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35
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Matsubayashi H, Kuruma Y, Ueda T. In Vitro Synthesis of theE. coliSec Translocon from DNA. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201403929] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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36
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Matsubayashi H, Kuruma Y, Ueda T. In Vitro Synthesis of theE. coliSec Translocon from DNA. Angew Chem Int Ed Engl 2014; 53:7535-8. [DOI: 10.1002/anie.201403929] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Indexed: 11/11/2022]
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37
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Aboulwafa M, Saier MH. Lipid dependencies, biogenesis and cytoplasmic micellar forms of integral membrane sugar transport proteins of the bacterial phosphotransferase system. MICROBIOLOGY-SGM 2013; 159:2213-2224. [PMID: 23985145 DOI: 10.1099/mic.0.070953-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Permeases of the prokaryotic phosphoenolpyruvate-sugar phosphotransferase system (PTS) catalyse sugar transport coupled to sugar phosphorylation. The lipid composition of a membrane determines the activities of these enzyme/transporters as well as the degree of coupling of phosphorylation to transport. We have investigated mechanisms of PTS permease biogenesis and identified cytoplasmic (soluble) forms of these integral membrane proteins. We found that the catalytic activities of the soluble forms differ from those of the membrane-embedded forms. Transport via the latter is much more sensitive to lipid composition than to phosphorylation, and some of these enzymes are much more sensitive to the lipid environment than others. While the membrane-embedded PTS permeases are always dimeric, the cytoplasmic forms are micellar, either monomeric or dimeric. Scattered published evidence suggests that other integral membrane proteins also exist in cytoplasmic micellar forms. The possible functions of cytoplasmic PTS permeases in biogenesis, intracellular sugar phosphorylation and permease storage are discussed.
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Affiliation(s)
- Mohammad Aboulwafa
- Department of Microbiology and Immunology, Faculty of Pharmacy, Ain Shams University, Abbasia, Cairo, Egypt.,Department of Molecular Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA
| | - Milton H Saier
- Department of Molecular Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA
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MPIase is a glycolipozyme essential for membrane protein integration. Nat Commun 2013; 3:1260. [PMID: 23232390 PMCID: PMC3535364 DOI: 10.1038/ncomms2267] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 11/07/2012] [Indexed: 11/16/2022] Open
Abstract
Protein integration into biological membranes is a vital cellular event for all organisms. We previously reported an integration factor in the inner membrane of Escherichia coli, named MPIase (membrane protein integrase). Here we show that in contrast to previously identified integration factors that are proteins, MPIase is a glycolipid composed of diacylglycerol and a glycan chain of three acetylated aminosugars linked through pyrophosphate. Hydrolytic removal of the lipid moiety gives a soluble product with higher integration activity than that of the original MPIase. This soluble form of MPIase directly interacts with a newborn membrane protein, maintaining its integration-competent structure and allowing its post-translational integration. MPIase actively drives protein integration following chaperoning membrane proteins. We further demonstrate with anti-MPIase antibodies that MPIase is likely involved in integration in vivo. Collectively, our results suggest that MPIase, essential for membrane protein integration, is to our knowledge the first glycolipid with an enzyme-like activity. Proteins are integrated into cellular membranes either co-translationally through Sec/SRP or post-translationally by chaperones. These authors show that an integration-dedicated chaperone in E. coli, MPIase, is a glycolipid and facilitates protein insertion into the inner membrane of the bacterium.
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Glycolipozyme MPIase is essential for topology inversion of SecG during preprotein translocation. Proc Natl Acad Sci U S A 2013; 110:9734-9. [PMID: 23716687 DOI: 10.1073/pnas.1303160110] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Presecretory proteins are translocated across biological membranes through protein-conducting channels such as Sec61 (eukaryotes) and SecYEG (bacteria). SecA, a translocation ATPase, pushes preproteins out with dynamic structural changes through SecYEG. SecG, a subunit of the SecYEG channel possessing two transmembrane stretches (TMs), undergoes topology inversion coupled with SecA-dependent translocation. Recently, we characterized membrane protein integrase (MPIase), a glycolipozyme involved in not only protein integration into membranes but also preprotein translocation. We report here that SecG inversion occurs only when MPIase associates with SecYEG. We also found that MPIase modulates the dimer orientation of SecYEG. Cysteine-scanning mutagenesis mapped SecG TM 2 to a relatively hydrophilic environment. The dimer formation of SecG, crosslinked at TM 2, was not observed on SecG inversion, indicating that SecYEG undergoes a dynamic structural change during preprotein translocation.
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40
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Long AR, O'Brien CC, Alder NN. The cell-free integration of a polytopic mitochondrial membrane protein into liposomes occurs cotranslationally and in a lipid-dependent manner. PLoS One 2012; 7:e46332. [PMID: 23050015 PMCID: PMC3457961 DOI: 10.1371/journal.pone.0046332] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 08/31/2012] [Indexed: 01/19/2023] Open
Abstract
The ADP/ATP Carrier (AAC) is the most abundant transporter of the mitochondrial inner membrane. The central role that this transporter plays in cellular energy production highlights the importance of understanding its structure, function, and the basis of its pathologies. As a means of preparing proteoliposomes for the study of membrane proteins, several groups have explored the use of cell-free translation systems to facilitate membrane protein integration directly into preformed unilamellar vesicles without the use of surfactants. Using AAC as a model, we report for the first time the detergent-free reconstitution of a mitochondrial inner membrane protein into liposomes using a wheat germ-based in vitro translation system. Using a host of independent approaches, we demonstrate the efficient integration of AAC into vesicles with an inner membrane-mimetic lipid composition and, more importantly, that the integrated AAC is functionally active in transport. By adding liposomes at different stages of the translation reaction, we show that this direct integration is obligatorily cotranslational, and by synthesizing stable ribosome-bound nascent chain intermediates, we show that the nascent AAC polypeptide interacts with lipid vesicles while ribosome-bound. Finally, we show that the presence of the phospholipid cardiolipin in the liposomes specifically enhances AAC translation rate as well as the efficiency of vesicle association and integration. In light of these results, the possible mechanisms of liposome-assisted membrane protein integration during cell-free translation are discussed with respect to the mode of integration and the role of specific lipids.
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Affiliation(s)
- Ashley R. Long
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Catherine C. O'Brien
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Nathan N. Alder
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, United States of America
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41
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Roos C, Kai L, Proverbio D, Ghoshdastider U, Filipek S, Dötsch V, Bernhard F. Co-translational association of cell-free expressed membrane proteins with supplied lipid bilayers. Mol Membr Biol 2012; 30:75-89. [PMID: 22716775 DOI: 10.3109/09687688.2012.693212] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Routine strategies for the cell-free production of membrane proteins in the presence of detergent micelles and for their efficient co-translational solubilization have been developed. Alternatively, the expression in the presence of rationally designed lipid bilayers becomes interesting in particular for biochemical studies. The synthesized membrane proteins would be directed into a more native-like environment and cell-free expression of transporters, channels or other membrane proteins in the presence of supplied artificial membranes could allow their subsequent functional analysis without any exposure to detergents. In addition, lipid-dependent effects on activity and stability of membrane proteins could systematically be studied. However, in contrast to the generally efficient detergent solubilization, the successful stabilization of membrane proteins with artificial membranes appears to be more difficult. A number of strategies have therefore been explored in order to optimize the co-translational association of membrane proteins with different forms of supplied lipid bilayers including liposomes, bicelles, microsomes or nanodiscs. In this review, we have compiled the current state-of-the-art of this technology and we summarize parameters which have been indicated as important for the co-translational association of cell-free synthesized membrane proteins with supplied membranes.
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Affiliation(s)
- Christian Roos
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe-University of Frankfurt/Main, Germany
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42
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Welte T, Kudva R, Kuhn P, Sturm L, Braig D, Müller M, Warscheid B, Drepper F, Koch HG. Promiscuous targeting of polytopic membrane proteins to SecYEG or YidC by the Escherichia coli signal recognition particle. Mol Biol Cell 2011; 23:464-79. [PMID: 22160593 PMCID: PMC3268725 DOI: 10.1091/mbc.e11-07-0590] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The YidC insertase also integrates multispanning membrane proteins that had been considered to be exclusively SecYEG dependent. Only membrane proteins that require SecA can be inserted only via SecYEG. Targeting to YidC is SRP dependent, and the C-terminus of YidC cross-links to SRP, FtsY, and ribosomal subunits. Protein insertion into the bacterial inner membrane is facilitated by SecYEG or YidC. Although SecYEG most likely constitutes the major integration site, small membrane proteins have been shown to integrate via YidC. We show that YidC can also integrate multispanning membrane proteins such as mannitol permease or TatC, which had been considered to be exclusively integrated by SecYEG. Only SecA-dependent multispanning membrane proteins strictly require SecYEG for integration, which suggests that SecA can only interact with the SecYEG translocon, but not with the YidC insertase. Targeting of multispanning membrane proteins to YidC is mediated by signal recognition particle (SRP), and we show by site-directed cross-linking that the C-terminus of YidC is in contact with SRP, the SRP receptor, and ribosomal proteins. These findings indicate that SRP recognizes membrane proteins independent of the downstream integration site and that many membrane proteins can probably use either SecYEG or YidC for integration. Because protein synthesis is much slower than protein transport, the use of YidC as an additional integration site for multispanning membrane proteins may prevent a situation in which the majority of SecYEG complexes are occupied by translating ribosomes during cotranslational insertion, impeding the translocation of secretory proteins.
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Affiliation(s)
- Thomas Welte
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany
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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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Junge F, Haberstock S, Roos C, Stefer S, Proverbio D, Dötsch V, Bernhard F. Advances in cell-free protein synthesis for the functional and structural analysis of membrane proteins. N Biotechnol 2011; 28:262-71. [DOI: 10.1016/j.nbt.2010.07.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 06/28/2010] [Accepted: 07/04/2010] [Indexed: 11/25/2022]
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M13 Procoat Protein Insertion into YidC and SecYEG Proteoliposomes and Liposomes. J Mol Biol 2011; 406:362-70. [DOI: 10.1016/j.jmb.2010.12.036] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2010] [Revised: 12/22/2010] [Accepted: 12/23/2010] [Indexed: 11/21/2022]
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Berrier C, Guilvout I, Bayan N, Park KH, Mesneau A, Chami M, Pugsley AP, Ghazi A. Coupled cell-free synthesis and lipid vesicle insertion of a functional oligomeric channel MscL. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:41-6. [DOI: 10.1016/j.bbamem.2010.09.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 09/22/2010] [Accepted: 09/23/2010] [Indexed: 10/19/2022]
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Price CE, Kocer A, Kol S, van der Berg JP, Driessen AJ. In vitro synthesis and oligomerization of the mechanosensitive channel of large conductance, MscL, into a functional ion channel. FEBS Lett 2010; 585:249-54. [DOI: 10.1016/j.febslet.2010.11.057] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 11/22/2010] [Indexed: 11/15/2022]
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A novel complete reconstitution system for membrane integration of the simplest membrane protein. Biochem Biophys Res Commun 2010; 394:733-6. [DOI: 10.1016/j.bbrc.2010.03.061] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 03/10/2010] [Indexed: 11/22/2022]
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Nishiyama KI, Tokuda H. Development of a functional in vitro integration system for an integral membrane protein, SecG. Biochem Biophys Res Commun 2009; 390:920-4. [PMID: 19853580 DOI: 10.1016/j.bbrc.2009.10.078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Accepted: 10/15/2009] [Indexed: 10/20/2022]
Abstract
A functional in vitro integration system for an integral membrane protein, SecG, comprising an efficient translation system supplemented with inverted membrane vesicles (IMV) was developed. When SecG was synthesized in the presence of IMV prepared from a DeltasecG strain (DeltaSecG IMV), the synthesized SecG was recovered with the IMV. A population of SecG was resistant to urea extraction, indicating that the synthesized SecG was integrated into DeltaSecG IMV. Addition of signal recognition particle and its receptor (SRP) and SecA caused an increase in the amount of the urea-resistant form of SecG. When IMV into which SecG had been integrated were subjected to the translocation assay, the translocation activity was found to be significantly stimulated compared with for DeltaSecG IMV. Moreover, when SRP and SecA had been supplemented, the translocation activity nearly recovered to the level in IMV prepared from the wild type strain. These results indicate that the in vitro synthesized SecG could be functionally integrated into DeltaSecG IMV with the help of SRP and SecA. We also present evidence that the membrane targeting and integration of SecG is stimulated by externally added SecA and SecG itself.
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Affiliation(s)
- Ken-ichi Nishiyama
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.
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Boy D, Koch HG. Visualization of distinct entities of the SecYEG translocon during translocation and integration of bacterial proteins. Mol Biol Cell 2009; 20:1804-15. [PMID: 19158385 DOI: 10.1091/mbc.e08-08-0886] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The universally conserved SecYEG/Sec61 translocon constitutes the major protein-conducting channel in the cytoplasmic membrane of bacteria and the endoplasmic reticulum membrane of eukaryotes. It is engaged in both translocating secretory proteins across the membrane as well as in integrating membrane proteins into the lipid phase of the membrane. In the current study we have detected distinct SecYEG translocon complexes in native Escherichia coli membranes. Blue-Native-PAGE revealed the presence of a 200-kDa SecYEG complex in resting membranes. When the SecA-dependent secretory protein pOmpA was trapped inside the SecYEG channel, a smaller SecY-containing complex of approximately 140-kDa was observed, which probably corresponds to a monomeric SecYEG-substrate complex. Trapping the SRP-dependent polytopic membrane protein mannitol permease in the SecYEG translocon, resulted in two complexes of 250 and 600 kDa, each containing both SecY and the translocon-associated membrane protein YidC. The appearance of both complexes was correlated with the number of transmembrane domains that were exposed during targeting of mannitol permease to the membrane. These results suggest that the assembly or the stability of the bacterial SecYEG translocon is influenced by the substrate that needs to be transported.
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Affiliation(s)
- Diana Boy
- Institut für Biochemie und Molekularbiologie, ZBMZ, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany
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