Mg2+ binding triggers rearrangement of the IM30 ring structure, resulting in augmented exposure of hydrophobic surfaces competent for membrane binding
The "inner membrane-associated protein of 30 kDa" (IM30), also known as "vesicle-inducing protein in plastids 1" (Vipp1), is found in the majority of photosynthetic organisms that use oxygen as an energy source, and its occurrence appears to be coupled to the existence of thylakoid membranes in cyanobacteria and chloroplasts. IM30 is most likely involved in thylakoid membrane biogenesis and/or maintenance, and has recently been shown to function as a membrane fusion protein in presence of Mg2+ However, the precise role of Mg2+ in this process and its impact on the structure and function of IM30 remains unknown. Here, we show that Mg2+ binds directly to IM30 with a binding affinity of ∼1 mm …
Extraordinary stability of hemocyanins from L. polyphemus and E. californicum studied using infrared spectroscopy from 294 to 20 K
International audience; Hemocyanins are large oligomeric respiratory proteins found in many arthropods and molluscs. Here we give infrared spectroscopic evidence of a high stability towards exposure to sub-zero temperatures for hemocyanins from the arthropods Limulus polyphemus and Eurypelma californicum at different pH values. Small but distinct temperature induced changes of the secondary structure were observed, but a stable core of at least 40% α-helical structure is preserved as identified in the infrared spectra obtained between 294 and 20 K. The structural changes differ in detail somewhat for the two hemocyanins, with overall fewer changes observed in the case of E. californicum. No…
Plasmonic Resonant Nanoantennas Induce Changes in the Shape and the Intensity of Infrared Spectra of Phospholipids.
Surface enhanced infrared absorption spectroscopic studies (SEIRAS) as a technique to study biological molecules in extremely low concentrations is greatly evolving. In order to use the technique for identification of the structure and interactions of such biological molecules, it is necessary to identify the effects of the plasmonic electric-field enhancement on the spectral signature. In this study the spectral properties of 1,2-Dipalmitoyl-sn-glycero-3 phosphothioethanol (DPPTE) phospholipid immobilized on gold nanoantennas, specifically designed to enhance the vibrational fingerprints of lipid molecules were studied. An AFM study demonstrates an organization of the DPPTE phospholipid in…