The helix bundle: A reversible lipid binding motif

Narayanaswami, Vasanthy; Kiss, Robert S.; Weers, Paul M.M.

doi:10.1016/j.cbpa.2009.09.009

Cited by 56 publications

(63 citation statements)

References 143 publications

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“…A similar structure was also found in the other homologous proteins of apoLp-III, such as apolipoprotein A-I (apoA-I) and apolipoprotein E (apoE) of animals [45][46][47][48]. Both are characterized by segments of amphipathic α-helices, which is responsible for lipid binding [49].…”

Section: Similarity To Lipid Transfer Proteinmentioning

confidence: 89%

Possible function of VIPP1 in maintaining chloroplast membranes

Zhang

Sakamoto

2015

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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A protein designated as VIPP1 is found widely in organisms performing oxygenic photosynthesis, but its precise role in chloroplasts has remained somewhat mysterious. Based on its structural similarity, it presumably has evolved from bacterial Phage shock protein A (PspA) with a C-terminal extension of approximately 40 amino acids. Both VIPP1 and PspA are membrane-associated despite the lack of transmembrane helices. They form an extremely large homo-complex that consists of an oligomeric ring unit. Although PspA is known to respond to membrane stress and although it acts in maintaining proton motive force through membrane repair, the multiple function of VIPP1, such as vesicle budding from inner envelope to deliver lipids to thylakoids, maintenance of photosynthetic complexes in thylakoid membranes, biogenesis of Photosystem I, and protective role of inner envelope against osmotic stress, has been proposed. Whatever its precise function in chloroplasts, it is an important protein because depletion of VIPP1 in mutants severely affects photoautotrophic growth. Recent reports of the relevant literature describe that VIPP1 becomes highly mobile when chloroplasts receive hypotonic stress, and that VIPP1 is tightly bound to lipids, which implies a crucial role of VIPP1 in membrane repair through lipid transfer. This review presents a summary of our current knowledge related to VIPP1, particularly addressing the dynamic behavior of complexes against stress and its property of lipid binding. Those data altogether suggest that VIPP1 acts a priori in chloroplast membrane maintenance through its activity to transfer lipids rather than in thylakoid formation through vesicles. This article is part of a Special Issue titled: Chloroplast Biogenesis.

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Section: Similarity To Lipid Transfer Proteinmentioning

confidence: 89%

Possible function of VIPP1 in maintaining chloroplast membranes

Zhang

Sakamoto

2015

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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“…ADPH(172-425) Directly Binds Membranes-The four-helix bundle is a common lipid-binding motif among the exchangeable apolipoproteins (37). Our homology model highlights the amphipathic nature of the ADPH C terminus with charged residues at the surface of the protein and hydrophobic residues buried within the helical bundle.…”

Section: Adenoviral Expression Of Gfp-adph(1-220) In Mammarymentioning

confidence: 91%

The Adipophilin C Terminus Is a Self-folding Membrane-binding Domain That Is Important for Milk Lipid Secretion

Chong

Russell

Schaack

et al. 2011

Journal of Biological Chemistry

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Cytoplasmic lipid droplets (CLD) in mammary epithelial cells undergo secretion by a unique membrane envelopment process to produce milk lipids. Adipophilin (ADPH/Plin2), a member of the perilipin/PAT family of lipid droplet-associated proteins, is hypothesized to mediate CLD secretion through interactions with apical plasma membrane elements. We found that the secretion of CLD coated by truncated ADPH lacking the C-terminal region encoding a putative four-helix bundle structure was impaired relative to that of CLD coated by full-length ADPH. We used homology modeling and analyses of the solution and membrane binding properties of purified recombinant ADPH C terminus to understand how this region possibly mediates CLD secretion. Homology modeling supports the concept that the ADPH C terminus forms a four-helix bundle motif and suggests that this structure can form stable membrane bilayer interactions. Circular dichroism and protease mapping studies confirmed that the ADPH C terminus is an independently folding ␣-helical structure that is relatively resistant to urea denaturation. Liposome binding studies showed that the purified C terminus binds to phospholipid membranes through electrostatic dependent interactions, and cell culture studies documented that it localizes to the plasma membrane. Collectively, these data provide direct evidence that the ADPH C terminus forms a stable membrane binding helical structure that is important for CLD secretion. We speculate that interactions between the four-helix bundle of ADPH and membrane phospholipids may be an initial step in milk lipid secretion.Milk lipids are an essential source of neonatal calories and provide nutrients in the form of fatty acids and bioactive lipids that are required for growth and development (1). Milk lipids are delivered to the newborn as milk fat globules (MFG) 4 derived from triglyceride-rich cytoplasmic lipid droplets (CLD) (2). Adipophilin (ADPH/ADRP/Adfp/Plin2), a member of the perilipin/PAT (perilipin/adipophilin/TIP47) family of proteins (3), is an abundant MFG protein (4 -6) and a prominent CLDassociated protein of mammary epithelial cells (7,8). PAT proteins have been shown to promote the formation and accumulation of CLD in a variety of tissues (9, 10) and are also implicated in the trafficking and secretion of CLD (2, 9). The lactating mammary gland is an ideal system to study the recurrent cycles of CLD formation, accumulation, and secretion, and previous work from our laboratory has implicated ADPH in each of these processes (5,8,11).CLD are secreted during lactation by an apocrine process where the apical plasma membrane engulfs associated CLD, which are then released by a budding process to form MFG (2). Two key regulators of CLD secretion are the transmembrane protein butyrophilin (BTN) and the cytoplasmic homodimer, xanthine oxidoreductase (XOR). Mice deficient in either of these proteins display impaired CLD envelopment and secretion (12, 13). In addition to being an abundant protein on mammary epithelial CLD and secreted MFG ...

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“…6. The ApoLp-III is thought to bind lipid and increases the lipid-carrying capacity of lipophorin by covering the expanding hydrophobic surface resulting from diacylglycerol uptake [58,59]. Here, we suggest that the N-acetyl groups formed by lysine acetylation may influence the conformation or enhance the hydrophobicity of the ApoLp-III surface, thus contributing to the binding to lipid.…”

Section: Lysine Acetylation May Represent a Common Regulatory Mechanimentioning

confidence: 93%

Comprehensive profiling of lysine acetylation suggests the widespread function is regulated by protein acetylation in the silkworm, Bombyx mori

et al. 2015

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Lysine acetylation in proteins is a dynamic and reversible PTM and plays an important role in diverse cellular processes. In this study, using lysine-acetylation (Kac) peptide enrichment coupled with nano HPLC/MS/MS, we initially identified the acetylome in the silkworms. Overall, a total of 342 acetylated proteins with 667 Kac sites were identified in silkworm. Sequence motifs analysis around Kac sites revealed an enrichment of Y, F, and H in the +1 position, and F was also enriched in the +2 and -2 positions, indicating the presences of preferred amino acids around Kac sites in the silkworm. Functional analysis showed the acetylated proteins were primarily involved in some specific biological processes. Furthermore, lots of nutrient-storage proteins, such as apolipophorin, vitellogenin, storage proteins, and 30 K proteins, were highly acetylated, indicating lysine acetylation may represent a common regulatory mechanism of nutrient utilization in the silkworm. Interestingly, Ser2 proteins, the coating proteins of larval silk, were found to contain many Kac sites, suggesting lysine acetylation may be involved in the regulation of larval silk synthesis. This study is the first to identify the acetylome in a lepidoptera insect, and expands greatly the catalog of lysine acetylation substrates and sites in insects.

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The helix bundle: A reversible lipid binding motif

Cited by 56 publications

References 143 publications

Possible function of VIPP1 in maintaining chloroplast membranes

Possible function of VIPP1 in maintaining chloroplast membranes

The Adipophilin C Terminus Is a Self-folding Membrane-binding Domain That Is Important for Milk Lipid Secretion

Comprehensive profiling of lysine acetylation suggests the widespread function is regulated by protein acetylation in the silkworm, Bombyx mori

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