Search results for "Protein folding"
showing 6 items of 196 documents
Crystal structure of the bifunctional soybean Bowman-Birk inhibitor at 0.28-nm resolution. Structural peculiarities in a folded protein conformation.
1996
The Bowman-Birk inhibitor from soybean is a small protein that contains a binary arrangement of trypsin-reactive and chymotrypsin-reactive subdomains. In this report, the crystal structure of this anticarcinogenic protein has been determined to 0.28-nm resolution by molecular replacement from crystals grown at neutral pH. The crystal structure differs from a previously determined NMR structure [Werner, M. H. & Wemmer, D. E. (1992) Biochemistry 31, 999-1010] in the relative orientation of the two enzyme-insertion loops, in some details of the main chain trace, in the presence of favourable contacts in the trypsin-insertion loop, and in the orientation of several amino acid side chains. The p…
Comparative analysis of the coordinated motion of Hsp70s from different organelles observed by single-molecule three-color FRET.
2021
Cellular function depends on the correct folding of proteins inside the cell. Heat-shock proteins 70 (Hsp70s), being among the first molecular chaperones binding to nascently translated proteins, aid in protein folding and transport. They undergo large, coordinated intra- and interdomain structural rearrangements mediated by allosteric interactions. Here, we applied a three-color single-molecule Forster resonance energy transfer (FRET) combined with three-color photon distribution analysis to compare the conformational cycle of the Hsp70 chaperones DnaK, Ssc1, and BiP. By capturing three distances simultaneously, we can identify coordinated structural changes during the functional cycle. Be…
Combinatorial chemistry of -hairpins
2000
Combinatorial chemistry is expanding rapidly both in terms of chemistry development and application to the synthesis of compound libraries for lead discovery and optimization. Combinatorial technologies continue evolving and developing, in fact they are being used as basic research tools in different fields that include peptide/protein folding. This review examines the use of combinatorial chemistry in the design of peptides and protein domains that adopt beta-sheet conformations. In particular, the use of conformationally restricted peptide libraries has allowed the identification of linear peptides that are folded in a beta-hairpin structure in plain aqueous solutions.
Pigment ligation to proteins of the photosynthetic apparatus in higher plants
1997
Ligation of pigments to proteins of the thylakoid membrane is a central step in the assembly of the photosynthetic apparatus in higher plants. Because of the potentially damaging photooxidative activity of chlorophylls, it is likely that between their biosynthesis and final assembly, chlorophylls will always be bound to protein complexes in which photooxidation is prevented by quenchers such as carotenoids. Such complexes may include chlorophyll carriers and/or membrane receptors involved in protein insertion into the membrane. Many if not all pigment-protein complexes of the thylakoid are stabilised towards protease attack by bound pigments. The major light-harvesting chlorophyll a/b prote…
Methionine in a protein hydrophobic core drives tight interactions required for assembly of spider silk
2019
Web spiders connect silk proteins, so-called spidroins, into fibers of extraordinary toughness. The spidroin N-terminal domain (NTD) plays a pivotal role in this process: it polymerizes spidroins through a complex mechanism of dimerization. Here we analyze sequences of spidroin NTDs and find an unusually high content of the amino acid methionine. We simultaneously mutate all methionines present in the hydrophobic core of a spidroin NTD from a nursery web spider’s dragline silk to leucine. The mutated NTD is strongly stabilized and folds at the theoretical speed limit. The structure of the mutant is preserved, yet its ability to dimerize is substantially impaired. We find that side chains of…
Viroporins, Examples of the Two-Stage Membrane Protein Folding Model
2015
Viroporins are small, α-helical, hydrophobic virus encoded proteins, engineered to form homo-oligomeric hydrophilic pores in the host membrane. Viroporins participate in multiple steps of the viral life cycle, from entry to budding. As any other membrane protein, viroporins have to find the way to bury their hydrophobic regions into the lipid bilayer. Once within the membrane, the hydrophobic helices of viroporins interact with each other to form higher ordered structures required to correctly perform their porating activities. This two-step process resembles the two-stage model proposed for membrane protein folding by Engelman and Poppot. In this review we use the membrane protein folding …