Protein "amyloid-like" networks at the phospholipid membrane formed by 4-hydroxy-2-nonenal-modified mitochondrial creatine kinase.

4-Hydroxy-2-nonenal (4-HNE) is a reactive aldehyde and a lipid peroxidation product formed in biological tissues under physiological and pathological conditions. Its concentration increases with oxidative stress and induces deleterious modifications of proteins and membranes. Mitochondrial and cytosolic isoforms of creatine kinase were previously shown to be affected by 4-HNE.

Acyl chain composition determines cardiolipin clustering induced by mitochondrial creatine kinase binding to monolayers.

It has been recently shown that mitochondrial creatine kinase (mtCK) organizes mitochondrial model membrane by modulating the state and fluidity of lipids and by promoting the formation of protein-cardiolipin clusters. This report shows, using Brewster angle microscopy, that such clustering is largely dependent on the acyl chain composition of phospholipids. Indeed, mtCK-cardiolipin domains were observed not only with unsaturated cardiolipins, but also with the cardiolipin precursor phosphatidylglycerol.

Male Phyllotreta striolata (F.) produce an aggregation pheromone: identification of male-specific compounds and interaction with host plant volatiles.

The chrysomelid beetle Phyllotreta striolata is an important pest of Brassicaceae in Southeast Asia and North America. Here, we identified the aggregation pheromone of a population of P. striolata from Taiwan, and host plant volatiles that interact with the pheromone.

Mitochondrial creatine kinase interaction with cardiolipin-containing biomimetic membranes is a two-step process involving adsorption and insertion.

Mitochondrial creatine kinase (mtCK) binding to the mitochondrial inner membrane largely determines its biological functions in cellular energy homeostasis, mitochondrial physiology, and dynamics. The membrane binding mechanism is, however, not completely understood. Recent data suggest that a hydrophobic component is involved in mtCK binding to cardiolipin at the outer face of the inner mitochondrial membrane, in addition to the well known electrostatically driven process.

Mitochondrial creatine kinase interaction with heterogeneous monolayers: Effect on lipid lateral organization.

Our study highlights the tight relationship between protein binding to monolayers and the phase-state of the phospholipids. Interaction of mitochondrial creatine kinase with phospholipidic membranes was analysed using a two-phase monolayer system containing anionic phospholipids under chain mismatch conditions. Monolayers were made up of mixtures of DMPC/DPPG or DPPC/DMPG containing 40% negatively charged phospholipids which is approximately the negative charge content of the mitochondrial inner membrane.

Mitochondrial creatine kinase binding to phospholipid monolayers induces cardiolipin segregation.

It is well established that the octameric mitochondrial form of creatine kinase (mtCK) binds to the outer face of the inner mitochondrial membrane mainly via electrostatic interactions with cardiolipin (CL). However, little is known about the consequences of these interactions on membrane and protein levels. Brewster angle microscopy investigations provide, for the first time to our knowledge, images indicating that mtCK binding induced cluster formation on CL monolayers.

Morphology modifications in negatively charged lipid monolayers upon mitochondrial creatine kinase binding.

Mitochondrial creatine kinase (mtCK) may participate to membrane organization at the mitochondrial level by modulating lipid state and fluidity. The effect of the protein on lipid phase behaviour of different acyl chain length phosphatidylglycerol monolayers was analyzed from pressure-area isotherms and from the compressional modulus variation with respect to the surface pressure. Monolayer morphology was visualized by Brewster angle microscopy.

Structure elucidation of a pungent compound in black cardamom: Amomum tsao-ko Crevost et Lemarié (Zingiberaceae).

Natural plant extracts containing taste modifier compounds will gain more commercial interest in the future. Black cardamom, Amomum tsao-ko Crevost et Lemarié, used as a spice in Asia, produces a nice refreshing effect in the mouth. Therefore, an ethyl acetate extract was prepared, and constituents were separated by liquid chromatography.

Mitochondrial creatine kinase adsorption to biomimetic membranes: a Langmuir monolayer study.

Interaction of mitochondrial creatine kinase (mtCK) with either synthetic or natural zwitterionic or acidic phospholipids was monitored by surface pressure measurements. Injection of mtCK beneath a monolayer at very low surface pressure results in a large increase in the apparent area per lipid molecule reflecting the intrinsic surface activity of the protein. This effect is particularly pronounced with anionic phospholipid-containing films.

Despite its high similarity with monomeric arginine kinase, muscle creatine kinase is only enzymatically active as a dimer.

Although having highly similar primary to tertiary structures, the different guanidino kinases exhibit distinct quaternary structures: monomer, dimer or octamer. However, no evidence for communication between subunits has yet been provided, and reasons for these different levels of quaternary complexity that can be observed from invertebrate to mammalian guanidino kinases remain elusive. Muscle creatine kinase is a dimer and disruption of the interface between subunits has been shown to give rise to destabilized monomers with slight residual activity; this low activity could, however, be due to a fraction of protein molecules present as dimer.

Interfacial behavior of cytoplasmic and mitochondrial creatine kinase oligomeric states.

Adsorption to the air/water interface of isoenzymes of creatine kinase was investigated using surface pressure-area isotherms and Brewster angle microscopy (BAM) observations. Octameric mitochondrial creatine kinase (mtCK) exhibits a significant affinity for the air/water interface. Whatever the mode of formation of the interfacial film, i.

Local dynamics measured by hydrogen/deuterium exchange and mass spectrometry of creatine kinase digested by two proteases.

Hydrogen/deuterium exchange coupled to mass spectrometry has been used to investigate the structure and dynamics of native dimeric cytosolic muscle creatine kinase. The protein was incubated in D2O for various time. After H/D exchange and rapid quenching of the reaction, the partially deuterated protein was cleaved in parallel by two different proteases (pepsin or type XIII protease from Aspergillus saitoi) to increase the sequence coverage and spatial resolution of deuterium incorporation.

Denaturant sensitive regions in creatine kinase identified by hydrogen/deuterium exchange.

The GdmHCl-induced unfolding of creatine kinase (CK) has been studied by hydrogen/deuterium (H/D) exchange combined with mass spectrometry. MM-CK unfolded for various periods in different denaturant concentrations was pulsed-labeled with deuterium to identify different conformational intermediate states. For all denaturation times or GdmHCl concentrations, we observed variable proportions of only two species.

Conformational dynamics of the GdmHCl-induced molten globule state of creatine kinase monitored by hydrogen exchange and mass spectrometry.

Our understanding of the mechanism of protein folding can be improved by the characterization of folding intermediate states. Intrinsic tryptophan fluorescence measurements of equilibrium GdmHCl-induced unfolding of MM-CK allow for the construction of a "phase diagram", which shows the presence of five different conformational states, including three partially folded intermediates. However, only three states are detected by using pulsed-labeled H-D exchange analyzed by electrospray ionization mass spectrometry.

C-terminal lysines determine phospholipid interaction of sarcomeric mitochondrial creatine kinase.

High affinity interaction between octameric mitochondrial creatine kinase (MtCK) and the phospholipid cardiolipin in the inner mitochondrial membrane plays an important role in metabolite channeling between MtCK and inner membrane adenylate translocator, which itself is tightly bound to cardiolipin. Three C-terminal basic residues revealed as putative cardiolipin anchors in the x-ray structures of MtCK and corresponding to lysines in human sarcomeric MtCK (sMtCK) were exchanged by in vitro mutagenesis (K369A/E, K379Q/A/E, K380Q/A/E) to yield double and triple mutants. sMtCK proteins were bacterially expressed, purified to homogeneity, and verified for structural integrity by enzymatic activity, gel filtration chromatography, and CD spectroscopy.

Hydrogen/deuterium exchange studies of native rabbit MM-CK dynamics.

Creatine kinase (CK) isoenzymes catalyse the reversible transfer of a phosphoryl group from ATP onto creatine. This reaction plays a very important role in the regulation of intracellular ATP concentrations in excitable tissues. CK isoenzymes are highly resistant to proteases in native conditions.

Changes in MM-CK conformational mobility upon formation of the ADP-Mg(2+)-NO(3)(-)-creatine transition state analogue complex as detected by hydrogen/deuterium exchange.

In the presence of ADP, Mg(2+), creatine, and the planar nitrate ion, creatine kinase isoenzymes undergo significant structural changes accompanying the formation of a very stable transition state analogue complex (TSAC). We have compared, by using hydrogen/deuterium exchange followed by proteolysis of the labeled enzyme and mass spectrometric analysis of the peptic peptides, the backbone dynamics fluctuations of the free enzyme and those of the TSAC. In most peptides, exchange is not affected by ligand binding, except that observed in seven areas located in or at the entrance to the active site, where some protection is detected.

Mg-nucleotides induced dissociation of liposome-bound creatine kinase: reversible changes in its secondary structure and in the fluidity of the bilayer.

MgADP binding to mitochondrial creatine kinase (mtCK) adsorbed on liposomes was induced by the photorelease of caged ADP. The nucleotide binding produced two types of structural changes. One was related to the well-established release of mtCK from the liposomes.

Role of C-terminal sequences in the folding of muscle creatine kinase.

Proteinase K selectively nicks the native homodimeric muscle creatine kinase (MM-CK) into two 37.1 kDa N-terminal (K1) and two 5.8 kDa C-terminal (K2) fragments that remain firmly associated in a native-like, although inactive, heterotetrameric structure.