Syntheses and Activities of the Functional Structures of a Glycolipid Essential for Membrane Protein Integration

Fujikawa, Kohki; Suzuki, Shohachi; Nagase, Ryohei; Ikeda, Shiori; Mori, Shoko; Nomura, Kaoru; Nishiyama, Kenichi; Shimamoto, Keiko

doi:10.1021/acschembio.8b00654

Cited by 25 publications

(59 citation statements)

References 46 publications

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“…These results suggested that the Sec/SRP-independent integration was generally controlled by DAG and MPIase. Structure-activity relationship studies revealed that the anchoring of MPIase in the membrane by its lipid moiety is essential for the membrane protein integration ( 13 ). The E. coli cell membrane is composed of a wide variety of lipid molecules that dynamically interact with each other.…”

Section: Discussionmentioning

confidence: 99%

“…The number of repeating trisaccharide units ranges from 7 to 14 but most are 9–11. Polysac-P was obtained by pyrophosphatase digestion of natural MPIase ( 12 , 13 ). …”

Section: Introductionmentioning

confidence: 99%

“…The DAG anchor moiety contains fatty acids such as C16:0, C16:1, C18:0, and C18:1, which are typical E. coli membrane lipid components. From structure-activity relationship studies, we deduced that the sugar chain of membrane protein integrase (MPIase) binds to the membrane protein and inhibits protein aggregation, similar to a chaperone ( 13 ). By adding both DAG and MPIase into EPL liposomes, we successfully obtained reconstituted systems for Sec/SRP-dependent and -independent membrane integration.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, we recently synthesized a minimal unit of MPIase called mini-MPIase-3 ( Fig. 1 c ), which possesses only one trisaccharide unit and a pyrophospholipid moiety ( 13 ). The integration by mini-MPIase-3 reached almost comparable levels to that by natural MPIase, although a higher dose was required ( Fig.…”

Section: Introductionmentioning

confidence: 99%

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Alteration of Membrane Physicochemical Properties by Two Factors for Membrane Protein Integration

Nomura

Yamaguchi

Mori

et al. 2019

Biophysical Journal

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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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Section: Discussionmentioning

confidence: 99%

“…The number of repeating trisaccharide units ranges from 7 to 14 but most are 9–11. Polysac-P was obtained by pyrophosphatase digestion of natural MPIase ( 12 , 13 ). …”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Alteration of Membrane Physicochemical Properties by Two Factors for Membrane Protein Integration

Nomura

Yamaguchi

Mori

et al. 2019

Biophysical Journal

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“…Our rst target compound was the minimal unit of MPIase, a trisaccharyl pyrophospholipid termed mini MPIase 3 (1) ( Figure 3). 14…”

Section: Syntheses Of Mpiase Derivativesmentioning

confidence: 99%

Novel Glycolipid Involved in Membrane Protein Integration: Structure and Mode of Action

Fujikawa

Nomura

Nishiyama

et al. 2019

J. Synth. Org. Chem. Jpn.

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Identi cation of MPIase 2.1 Endogenous Membrane Components Regulating Membrane Protein Integration In the course of constructing an in vitro integration system, it became evident that arti cial (proteo) liposomes using E. coli phospholipids (EPL) could not reproduce membrane integration in a precise manner. For example, a Sec/SRP dependent protein can spontaneously integrate into membranes even without the assistance of translocons or YidC. 8b,9 We assumed that there are additional unknown factors that regulate the integration pathways. We searched for them in the inner membrane of E. coli and found that two endogenous membrane components are involved in integration. First, diacylglycerol (DAG) inhibits integration, 9,10 and second, an unknown factor that we eventually termed membrane protein integrase assists with the integration. 8a,11 DAG prevents indiscriminate spontaneous integration in biomembranes, which is important because biomembranes cannot function as barriers if anything with a hydrophobic moiety could embed into them. DAG is a minor component of the inner membrane of E. coli and consists of 2 3 wt% of E. coli membrane lipids. Spontaneous integration into EPL lipo

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Two‐step induction of cdsA promoters leads to upregulation of the glycolipid MPIase at cold temperature

2019

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Glycolipid MPIase, essential for membrane protein integration into the cytoplasmic membrane of Escherichia coli, is upregulated at cold temperatures. This upregulation is rapid and sustainable. CdsA, a CDP‐diacylglycerol synthase, is a rate‐limiting enzyme for MPIase biosynthesis. Upregulation of CdsA is responsible for the increase in the MPIase level at low temperature. Investigation of cdsA regulatory regions revealed at least two cold‐inducible promoters, a cold‐shock promoter that functions transiently and immediately in the cold, and one that is sustainable in the cold. The stability of the cdsA transcript was comparable with that of tufA, which is not cold‐inducible. Thus, cdsA is induced through two‐step cold‐induction to maintain MPIase at a high level rapidly and sustainably in the cold.

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Syntheses and Activities of the Functional Structures of a Glycolipid Essential for Membrane Protein Integration

Cited by 25 publications

References 46 publications

Alteration of Membrane Physicochemical Properties by Two Factors for Membrane Protein Integration

Alteration of Membrane Physicochemical Properties by Two Factors for Membrane Protein Integration

Novel Glycolipid Involved in Membrane Protein Integration: Structure and Mode of Action

Two‐step induction of cdsA promoters leads to upregulation of the glycolipid MPIase at cold temperature

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