Conformational Changes in ι- and κ-Carrageenans Induced by Complex Formation with Bovine β-Casein

2007 ◽  
Vol 8 (2) ◽  
pp. 368-375 ◽  
Author(s):  
Tatiana V. Burova ◽  
Natalia V. Grinberg ◽  
Valerij Ya. Grinberg ◽  
Anatoly I. Usov ◽  
Vladimir B. Tolstoguzov ◽  
...  
Keyword(s):  
Complex Formation ◽  
Conformational Changes

scholarly journals Conformational Change of Syntaxin-3b in Regulating SNARE Complex Assembly in the Ribbon Synapses

2021 ◽  
Author(s):  
Claire Gething ◽  
Joshua Ferrar ◽  
Bishal Misra ◽  
Giovanni Howells ◽  
Ucheor B. Choi
Keyword(s):  
Plasma Membrane ◽  
Complex Formation ◽  
Synaptic Vesicle ◽  
Conformational Change ◽  
Single Molecule ◽  
Conformational Changes ◽  
Snare Complex ◽  
Complex Assembly ◽  
Ribbon Synapses ◽  
Snare Complex Formation

AbstractNeurotransmitter release of synaptic vesicles relies on the assembly of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex, consisting of syntaxin and SNAP-25 on the plasma membrane and synaptobrevin on the synaptic vesicle. The formation of the SNARE complex progressively zippers towards the membranes, which drives membrane fusion between the plasma membrane and the synaptic vesicle. However, the underlying molecular mechanism of SNARE complex regulation is unclear. In this study, we investigate the syntaxin-3b isoform found in the retinal ribbon synapses using single-molecule fluorescence resonance energy transfer (smFRET) to monitor the conformational changes of syntaxin-3b that modulate the SNARE complex formation. We found that syntaxin-3b is predominantly in a self-inhibiting closed conformation, inefficiently forming the ternary SNARE complex. Conversely, a phosphomimetic mutation (T14E) at the N-terminal region of syntaxin-3b promoted the open conformation, similar to the constitutively open form of syntaxin LE mutant. When syntaxin-3b is bound to Munc18-1, SNARE complex formation is almost completely blocked. Surprisingly, the T14E mutation of syntaxin-3b partially abolishes Munc18-1 regulation, acting as a conformational switch to trigger SNARE complex assembly. Thus, we suggest a model where the conformational change of syntaxin-3b induced by phosphorylation initiates the release of neurotransmitters in the ribbon synapses.

scholarly journals Ureidothiophene inhibits interaction of bacterial RNA polymerase with –10 promotor element

2020 ◽  
Vol 48 (14) ◽  
pp. 7914-7923
Author(s):  
John Harbottle ◽  
Nikolay Zenkin
Keyword(s):  
Complex Formation ◽  
Rna Polymerase ◽  
Conformational Changes ◽  
Early Stage ◽  
Chemical Compounds ◽  
Initiation Factor ◽  
Promoter Element ◽  
Bacterial Transcription ◽  
Bacterial Rna ◽  
Novel Target

Abstract Bacterial RNA polymerase is a potent target for antibiotics, which utilize a plethora of different modes of action, some of which are still not fully understood. Ureidothiophene (Urd) was found in a screen of a library of chemical compounds for ability to inhibit bacterial transcription. The mechanism of Urd action is not known. Here, we show that Urd inhibits transcription at the early stage of closed complex formation by blocking interaction of RNA polymerase with the promoter –10 element, while not affecting interactions with –35 element or steps of transcription after promoter closed complex formation. We show that mutation in the region 1.2 of initiation factor σ decreases sensitivity to Urd. The results suggest that Urd may directly target σ region 1.2, which allosterically controls the recognition of –10 element by σ region 2. Alternatively, Urd may block conformational changes of the holoenzyme required for engagement with –10 promoter element, although by a mechanism distinct from that of antibiotic fidaxomycin (lipiarmycin). The results suggest a new mode of transcription inhibition involving the regulatory domain of σ subunit, and potentially pinpoint a novel target for development of new antibacterials.

Circulating IgG-LD complex, dissociable by addition of NAD+.

1982 ◽  
Vol 28 (1) ◽  
pp. 236-239 ◽  
Author(s):  
F Gorus ◽  
W Aelbrecht ◽  
B Van Camp
Keyword(s):  
Lactate Dehydrogenase ◽  
Autoimmune Disease ◽  
Complex Formation ◽  
Affinity Chromatography ◽  
Conformational Changes ◽  
Active Site ◽  
Nicotinamide Adenine Dinucleotide ◽  
Binding Sites ◽  
Gel Filtration ◽  
Binding Studies

Abstract Macromolecular LD (lactate dehydrogenase, EC 1.1.1.27) was present in the serum of a patient suffering from idiopathic fibrosis of the lung and presenting signs of autoimmune disease. By using gel filtration and affinity chromatography techniques, the vast majority of the patient's serum LD activity was shown to consist of LD-IgG complexes, which dissociated in the presence of added nicotinamide adenine dinucleotide (NAD+). Binding studies with tritiated NAD+ indicated that complex formation was not ascribable to a lack of circulating cofactor. The most likely explanation for the complex formation was the existence of LD binding sites on IgG molecules. The disruption of the complex by NAD+ might be explained by a competition between IgG molecules and NAD+ for the LD active site or by conformational changes induced in the LD molecules on binding of NAD+.

Conformational changes in cytochrome c and cytochrome oxidase upon complex formation: a resonance Raman study

Biochemistry ◽  
1990 ◽  
Vol 29 (6) ◽  
pp. 1661-1668 ◽  
Author(s):  
Peter Hildebrandt ◽  
Thomas Heimburg ◽  
Derek Marsh ◽  
Gary L. Powell
Keyword(s):  
Cytochrome C ◽  
Complex Formation ◽  
Cytochrome Oxidase ◽  
Conformational Changes ◽  
Resonance Raman ◽  
Raman Study

Conformational Changes of the BS2 Operator DNA upon Complex Formation with the Antennapedia Homeodomain Studied by NMR with13C/15N-labeled DNA

1999 ◽  
Vol 292 (3) ◽  
pp. 609-617 ◽  
Author(s):  
César Fernández ◽  
Thomas Szyperski ◽  
Martin Billeter ◽  
Akira Ono ◽  
Hideo Iwai ◽  
...  
Keyword(s):  
Complex Formation ◽  
Conformational Changes ◽  
Operator Dna

scholarly journals Probing serpin reactive-loop conformations by proteolytic cleavage

1996 ◽  
Vol 314 (2) ◽  
pp. 647-653 ◽  
Author(s):  
Wun-Shaing W. CHANG ◽  
Mark R. WARDELL ◽  
David A. LOMAS ◽  
Robin W. CARRELL
Keyword(s):  
Complex Formation ◽  
Conformational Changes ◽  
Limited Proteolysis ◽  
Serine Proteinase ◽  
Hinge Region ◽  
Helical Conformation ◽  
Binary Complex ◽  
Native Form ◽  
Binary Complexes ◽  
Loop Conformations

Several crystal structures of intact members of the serine proteinase inhibitor (or serpin) superfamily have recently been solved but the relationship of their reactive-loop conformations to those of circulating forms remains unclear. Here we examine reactive-loop conformational changes of anti-trypsin and anti-thrombin by using limited proteolysis and binary complex formation with synthetic homologous reactive-loop peptides. Proteolysis at the P10–P9, P8–P7 and P7–P6 of anti-trypsin was distorted by binary complex formation. The P1´–P2´ bond in anti-thrombin was more accessible to proteolysis after binary complex formation, whereas cleavage at the P4–P3 bond was variably altered by synthetic peptide insertion. The proteolytic accessibility of the reactive-site P1–P1´ bond of anti-trypsin and anti-thrombin binary complexes was identical with that of the native form and no cleavage was observed in the hinge region (P15–P10) of either protein, whether native or as binary complexes. These results fit with the proposal that the hydrophobic reactive loop of serpins adopts a modified helical conformation in the circulation, with the hinge region being partly incorporated into the A β-pleated sheet. This loop can be displaced by peptides and induced to adopt a new conformation similar to the three-turn helix of ovalbumin. Both the native and binary complexed forms of anti-thrombin showed a greatly increased proteolytic sensitivity in the presence of heparin, indicating that heparin either induces a conformational change in the local structure of the helical reactive loop or facilitates the approximation of enzyme and inhibitor.

Sign in / Sign up

Export Citation Format

Share Document