scholarly journals The Role of Membranes and Lipid-Protein Interactions in the Mg-Branch of Tetrapyrrole Biosynthesis

2021 ◽  
Vol 12 ◽  
Author(s):  
Katalin Solymosi ◽  
Beata Mysliwa-Kurdziel
Keyword(s):  
Protein Interactions ◽  
Photophysical Properties ◽  
Spectroscopic Properties ◽  
Prolamellar Body ◽  
Tetrapyrrole Biosynthesis ◽  
Whole Plant ◽  
Lipid Protein Interactions ◽  
Envelope Membranes

Chlorophyll (Chl) is essential for photosynthesis and needs to be produced throughout the whole plant life, especially under changing light intensity and stress conditions which may result in the destruction and elimination of these pigments. All steps of the Mg-branch of tetrapyrrole biosynthesis leading to Chl formation are carried out by enzymes associated with plastid membranes. Still the significance of these protein-membrane and protein-lipid interactions in Chl synthesis and chloroplast differentiation are not very well-understood. In this review, we provide an overview on Chl biosynthesis in angiosperms with emphasis on its association with membranes and lipids. Moreover, the last steps of the pathway including the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), the biosynthesis of the isoprenoid phytyl moiety and the esterification of Chlide are also summarized. The unique biochemical and photophysical properties of the light-dependent NADPH:protochlorophyllide oxidoreductase (LPOR) enzyme catalyzing Pchlide photoreduction and located to peculiar tubuloreticular prolamellar body (PLB) membranes of light-deprived tissues of angiosperms and to envelope membranes, as well as to thylakoids (especially grana margins) are also reviewed. Data about the factors influencing tubuloreticular membrane formation within cells, the spectroscopic properties and the in vitro reconstitution of the native LPOR enzyme complexes are also critically discussed.

Visualizing signalling by phosphoinositide 3-kinase pathway lipids

2004 ◽  
Vol 32 (2) ◽  
pp. 336-337 ◽  
Author(s):  
G.D. Prestwich
Keyword(s):  
Enzyme Activity ◽  
Protein Interactions ◽  
Phosphoinositide Metabolism ◽  
University Of Utah ◽  
Phosphodiester Hydrolysis ◽  
Phosphoinositide 3 Kinase ◽  
Lipid Protein Interactions ◽  
The University ◽  
Hydroxy Groups

Cells signal through lipids produced by phospholipid and phosphoinositide metabolism that involves three enzymic processes: (i) ester and phosphodiester hydrolysis by phospholipases; (ii) monophosphate hydrolysis by phosphatases; and (iii) phosphorylation of hydroxy groups by kinases. Unregulated enzyme activity correlates with specific pathologies, which are specific targets for therapeutic intervention. Three categories of reagents developed at the University of Utah and at Echelon Biosciences permit monitoring of in vitro enzyme activity and spatiotemporal changes in intracellular lipid concentrations, and identification of lipid–protein interactions.

Divalent cation and lipid-protein interactions of biomembranes

1993 ◽  
Vol 13 (3) ◽  
pp. 143-157 ◽  
Author(s):  
F. Y. Yang ◽  
Y. G. Huang ◽  
Y. P. Tu
Keyword(s):  
Adenylate Cyclase ◽  
Atpase Activity ◽  
Enzymatic Activity ◽  
Divalent Cation ◽  
Protein Interactions ◽  
Physical State ◽  
Divalent Cations ◽  
Activity Change ◽  
Lipid Protein Interactions

Divalent cations play an important role in the functions of biomembranes. This review deals with three topics: (1) Mg2+-mediated change in physical state of phospholipid induces conformation and activity change of reconstituted mitochondrial H+-ATPase, (2) a proper transmembrane Ca2+ gradient is essential for the higher enzymatic activity of adenylate cyclase, and (3) role of transmembrane Ca2+ gradient in the modulation of reconstituted sarcoplasmic reticulm Ca2+-ATPase activity.

scholarly journals A Novel Interaction of Ecdysoneless (ECD) Protein with R2TP Complex Component RUVBL1 Is Required for the Functional Role of ECD in Cell Cycle Progression

2015 ◽  
Vol 36 (6) ◽  
pp. 886-899 ◽  
Author(s):  
Riyaz A. Mir ◽  
Aditya Bele ◽  
Sameer Mirza ◽  
Shashank Srivastava ◽  
Appolinaire A. Olou ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Protein Interactions ◽  
Cell Cycle Progression ◽  
Germ Line ◽  
Regulatory Function ◽  
Cycle Progression ◽  
Cycle Arrest

Ecdysoneless (ECD) is an evolutionarily conserved protein whose germ line deletion is embryonic lethal. Deletion ofEcdin cells causes cell cycle arrest, which is rescued by exogenousECD, demonstrating a requirement ofECDfor normal mammalian cell cycle progression. However, the exact mechanism by which ECD regulates cell cycle is unknown. Here, we demonstrate that ECD protein levels and subcellular localization are invariant during cell cycle progression, suggesting a potential role of posttranslational modifications or protein-protein interactions. Since phosphorylated ECD was recently shown to interact with the PIH1D1 adaptor component of the R2TP cochaperone complex, we examined the requirement of ECD phosphorylation in cell cycle progression. Notably, phosphorylation-deficient ECD mutants that failed to bind to PIH1D1in vitrofully retained the ability to interact with the R2TP complex and yet exhibited a reduced ability to rescueEcd-deficient cells from cell cycle arrest. Biochemical analyses demonstrated an additional phosphorylation-independent interaction of ECD with the RUVBL1 component of the R2TP complex, and this interaction is essential for ECD's cell cycle progression function. These studies demonstrate that interaction of ECD with RUVBL1, and its CK2-mediated phosphorylation, independent of its interaction with PIH1D1, are important for its cell cycle regulatory function.

scholarly journals A proline-rich sequence unique to MEK1 and MEK2 is required for raf binding and regulates MEK function.

1995 ◽  
Vol 15 (10) ◽  
pp. 5214-5225 ◽  
Author(s):  
A D Catling ◽  
H J Schaeffer ◽  
C W Reuter ◽  
G R Reddy ◽  
M J Weber
Keyword(s):  
Protein Interactions ◽  
Critical Role ◽  
Phosphorylation Site ◽  
Specific Protein ◽  
Protein Protein Interactions ◽  
Serum Stimulation ◽  
And Function

Mammalian MEK1 and MEK2 contain a proline-rich (PR) sequence that is absent both from the yeast homologs Ste7 and Byr1 and from a recently cloned activator of the JNK/stress-activated protein kinases, SEK1/MKK4. Since this PR sequence occurs in MEKs that are regulated by Raf family enzymes but is missing from MEKs and SEKs activated independently of Raf, we sought to investigate the role of this sequence in MEK1 and MEK2 regulation and function. Deletion of the PR sequence from MEK1 blocked the ability of MEK1 to associate with members of the Raf family and markedly attenuated activation of the protein in vivo following growth factor stimulation. In addition, this sequence was necessary for efficient activation of MEK1 in vitro by B-Raf but dispensable for activation by a novel MEK1 activator which we have previously detected in fractionated fibroblast extracts. Furthermore, we found that a phosphorylation site within the PR sequence of MEK1 was required for sustained MEK1 activity in response to serum stimulation of quiescent fibroblasts. Consistent with this observation, we observed that MEK2, which lacks a phosphorylation site at the corresponding position, was activated only transiently following serum stimulation. Finally, we found that deletion of the PR sequence from a constitutively activated MEK1 mutant rendered the protein nontransforming in Rat1 fibroblasts. These observations indicate a critical role for the PR sequence in directing specific protein-protein interactions important for the activation, inactivation, and downstream functioning of the MEKs.

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