scholarly journals Nanodiscs-based proteomics identify Caj1 as an Hsp40 with affinity for phosphatidic acid lipids

2021 ◽  
Author(s):  
Xiao Xiao Zhang ◽  
John William Young ◽  
Leonard J Foster ◽  
Franck Duong
Keyword(s):  
Phosphatidic Acid ◽  
Protein Quality ◽  
Lipid Binding ◽  
Water Soluble ◽  
Rab Gtpases ◽  
Small Water ◽  
Transient Nature ◽  
C Terminus ◽  
Lipid Binding Proteins ◽  
Lipid Specificity

Many soluble proteins interact with membranes to perform important biological functions, including signal transduction, regulation, transport, trafficking and biogenesis. Despite their importance, these protein-membrane interactions are difficult to characterize due to their often-transient nature as well as phospholipids' poor solubility in aqueous solution. Here, we employ nanodiscs - small, water-soluble patches of lipid bilayer encircled with amphipathic scaffold proteins - along with quantitative proteomics to identify lipid-binding proteins in S. cerevisiae. Using nanodiscs reconstituted with yeast total lipid extracts or only phosphatidylethanolamine (PE-nanodiscs), we capture several known membrane-interacting proteins, including the Rab GTPases Sec4 and Ypt1, which play key roles in vesicle trafficking. Utilizing PE-nanodiscs enriched with phosphatidic acid (PEPA-nanodiscs), we specifically capture a member of the Hsp40/J-protein family, Caj1, whose function has recently been linked to membrane protein quality control. We show that Caj1 interaction with liposomes containing PA is modulated by pH and PE lipids, and depends on two patches of positively charged residues near the C-terminus of the protein. The protein Caj1 is the first example of an Hsp40/J-domain protein with affinity for membranes and phosphatidic acid lipid specificity. These findings highlight the utility of the nanodisc system to identify and characterize protein-lipid interactions that may not be evident using other methods.

scholarly journals Synthesis of Highly Water-Soluble Adamantyl Phosphoinositide Derivatives

2015 ◽  
Vol 68 (4) ◽  
pp. 543 ◽  
Author(s):  
Mark Gregory ◽  
Meng-Xin Yin ◽  
Malcolm J. McConville ◽  
Eleanor Williams ◽  
Alex N. Bullock ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Binding Proteins ◽  
Cell Signalling ◽  
Lipid Binding ◽  
Water Soluble ◽  
Side Chains ◽  
Phosphatidylinositol Phosphate ◽  
Phosphatidylinositol Phosphates ◽  
Lipid Binding Proteins ◽  
Natural Lipid

Phosphatidylinositol phosphates are key regulators of cell signalling pathways and membrane trafficking in eukaryotic cells, and there is a need for new chemical probes to further understand how they interact with lipid-binding proteins. Here, the synthesis of phosphatidylinositol phosphate analogues containing adamantyl carboxylic ester groups, in place of the natural lipid side chains, is described. These derivatives are considerably more soluble in water than analogues containing other lipid side chains and do not form large aggregates such as liposomes or micelles. These adamantyl analogues bind to known phosphoinositide-binding proteins with similar affinities to native ligands and will facilitate future studies on the substrate specificities of these proteins involving cocrystallisation studies with proteins.

scholarly journals Identification and characterization of the lipid-binding property of GrlR, a locus of enterocyte effacement regulator

2009 ◽  
Vol 420 (2) ◽  
pp. 191-201 ◽  
Author(s):  
Chacko Jobichen ◽  
Aaron Z. Fernandis ◽  
Adrian Velazquez-Campoy ◽  
Ka Yin Leung ◽  
Yu-Keung Mok ◽  
...  
Keyword(s):  
Lipid Binding ◽  
Titration Calorimetry ◽  
Binding Property ◽  
C Terminus ◽  
Lipid Species ◽  
Unknown Lipid ◽  
Enterocyte Effacement ◽  
Highly Hydrophobic ◽  
Α Helix ◽  
Lipid Binding Proteins

Lipocalins are a broad family of proteins identified initially in eukaryotes and more recently in Gram-negative bacteria. The functions of lipocalin or lipid-binding proteins are often elusive and very diverse. Recently, we have determined the structure of GrlR (global regulator of LEE repressor), which plays a key role in the regulation of LEE (locus of enterocyte effacement) proteins. GrlR adopts a lipocalin-like fold that is composed of an eight-stranded β-barrel followed by an α-helix at the C-terminus. GrlR has a highly hydrophobic cavity region and could be a potential transporter of lipophilic molecules. To verify this hypothesis, we carried out structure-based analysis of GrlR, determined the structure of the lipid–GrlR complex and measured the binding of lipid to recombinant GrlR by ITC (isothermal titration calorimetry). In addition, we identified phosphatidylglycerol and phosphatidylethanolamine as the endogenously bound lipid species of GrlR using electrospray-ionization MS. Furthermore, we have shown that the lipid-binding property of GrlR is similar to that of its closest lipocalin structural homologue, β-lactoglobulin. Our studies demonstrate the hitherto unknown lipid-binding property of GrlR.

The role of dynamics in modulating ligand exchange in intracellular lipid binding proteins

2014 ◽  
Vol 1844 (7) ◽  
pp. 1268-1278 ◽  
Author(s):  
Laura Ragona ◽  
Katiuscia Pagano ◽  
Simona Tomaselli ◽  
Filippo Favretto ◽  
Alberto Ceccon ◽  
...  
Keyword(s):  
Ligand Exchange ◽  
Binding Proteins ◽  
Lipid Binding ◽  
Intracellular Lipid ◽  
Lipid Binding Proteins

scholarly journals INTRACELLULAR LIPID-BINDING PROTEINS AND THEIR GENES

1997 ◽  
Vol 17 (1) ◽  
pp. 277-303 ◽  
Author(s):  
David A. Bernlohr ◽  
Melanie A. Simpson ◽  
Ann Vogel Hertzel ◽  
Leonard J. Banaszak
Keyword(s):  
Binding Proteins ◽  
Lipid Binding ◽  
Intracellular Lipid ◽  
Lipid Binding Proteins

HYDROLYSIS OF LECITHIN BY PLANT PLASTID ENZYMES

1955 ◽  
Vol 33 (1) ◽  
pp. 575-589 ◽  
Author(s):  
Morris Kates
Keyword(s):  
Phosphatidic Acid ◽  
Inorganic Phosphate ◽  
Organic Phosphate ◽  
Water Soluble ◽  
Lag Phase ◽  
Carrot Root ◽  
First Order ◽  
Spinach Chloroplasts ◽  
Egg Lecithin ◽  
Hydrolysis Of

Enzymatic liberation of choline from egg lecithin by plastid fractions from sugar beet, spinach, and cabbage leaves and from carrot root was a rapid, first order reaction (up to 70% hydrolysis), and was not preceded by a lag phase. None of the choline-containing products of lecithin degradation (lysolecithin, glycerylphosphorylcholine, or phosphorylcholine) lost choline on incubation with spinach chloroplasts. Inorganic phosphate liberation from lecithin by the plastids was preceded by a lag phase and was much slower than choline liberation. Spinach chloroplasts catalyzed the liberation of inorganic phosphate from L-α-phosphatidic acid and from L-α-glycerophosphate. The water-soluble organic phosphate liberated from lecithin by spinach chloroplasts was identified chromatographically as phosphorylcholine. The ether-soluble organic phosphate produced during the hydrolysis of egg lecithin by carrot plastids was isolated and identified as L-α-phosphatidic acid. These observations suggest that the enzymatic hydrolysis of lecithin by plant plastids involves the following reactions: (1) lecithin → L-α-phosphatidic acid + choline; (2) L-α-phosphatidic acid → inorganic phosphate + diglyceride and/or (3) L-α-phosphatidic acid → glycerophosphate + fatty acids and (4) glycerophosphate → inorganic phosphate + glycerol; and (5) lecithin → phosphorylcholine + diglyceride. The L-α-structure for egg lecithin was confirmed.

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