@article{WolffGastEversetal.2021,
  author    = {Wolff, Martin and Gast, Klaus and Evers, Andreas and Kurz, Michael and Pfeiffer-Marek, Stefania and Sch{\"u}ler, Anja and Seckler, Robert and Thalhammer, Anja},
  title     = {A Conserved Hydrophobic Moiety and Helix-Helix Interactions Drive the Self-Assembly of the Incretin Analog Exendin-4},
  series = {Biomolecules},
  volume    = {11},
  journal   = {Biomolecules},
  number    = {9},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2218-273X},
  doi       = {10.3390/biom11091305},
  pages     = {20},
  year      = {2021},
  abstract  = {Exendin-4 is a pharmaceutical peptide used in the control of insulin secretion. Structural information on exendin-4 and related peptides especially on the level of quaternary structure is scarce. We present the first published association equilibria of exendin-4 directly measured by static and dynamic light scattering. We show that exendin-4 oligomerization is pH dependent and that these oligomers are of low compactness. We relate our experimental results to a structural hypothesis to describe molecular details of exendin-4 oligomers. Discussion of the validity of this hypothesis is based on NMR, circular dichroism and fluorescence spectroscopy, and light scattering data on exendin-4 and a set of exendin-4 derived peptides. The essential forces driving oligomerization of exendin-4 are helix-helix interactions and interactions of a conserved hydrophobic moiety. Our structural hypothesis suggests that key interactions of exendin-4 monomers in the experimentally supported trimer take place between a defined helical segment and a hydrophobic triangle constituted by the Phe22 residues of the three monomeric subunits. Our data rationalize that Val19 might function as an anchor in the N-terminus of the interacting helix-region and that Trp25 is partially shielded in the oligomer by C-terminal amino acids of the same monomer. Our structural hypothesis suggests that the Trp25 residues do not interact with each other, but with C-terminal Pro residues of their own monomers.},
  language  = {en}
}
@misc{WolffGastEversetal.2021,
  author    = {Wolff, Martin and Gast, Klaus and Evers, Andreas and Kurz, Michael and Pfeiffer-Marek, Stefania and Sch{\"u}ler, Anja and Seckler, Robert and Thalhammer, Anja},
  title     = {A Conserved Hydrophobic Moiety and Helix-Helix Interactions Drive the Self-Assembly of the Incretin Analog Exendin-4},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {9},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-52208},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-522081},
  pages     = {22},
  year      = {2021},
  abstract  = {Exendin-4 is a pharmaceutical peptide used in the control of insulin secretion. Structural information on exendin-4 and related peptides especially on the level of quaternary structure is scarce. We present the first published association equilibria of exendin-4 directly measured by static and dynamic light scattering. We show that exendin-4 oligomerization is pH dependent and that these oligomers are of low compactness. We relate our experimental results to a structural hypothesis to describe molecular details of exendin-4 oligomers. Discussion of the validity of this hypothesis is based on NMR, circular dichroism and fluorescence spectroscopy, and light scattering data on exendin-4 and a set of exendin-4 derived peptides. The essential forces driving oligomerization of exendin-4 are helix-helix interactions and interactions of a conserved hydrophobic moiety. Our structural hypothesis suggests that key interactions of exendin-4 monomers in the experimentally supported trimer take place between a defined helical segment and a hydrophobic triangle constituted by the Phe22 residues of the three monomeric subunits. Our data rationalize that Val19 might function as an anchor in the N-terminus of the interacting helix-region and that Trp25 is partially shielded in the oligomer by C-terminal amino acids of the same monomer. Our structural hypothesis suggests that the Trp25 residues do not interact with each other, but with C-terminal Pro residues of their own monomers.},
  language  = {en}
}
@article{GastDamaschunDesmadriletal.1995,
  author    = {Gast, Klaus and Damaschun, Gregor and Desmadril, Michel and Minard, Philippe and M{\"u}ller-Frohne, Marlies and Pfeil, Wolfgang and Zirwer, Dietrich},
  title     = {Cold denaturation of yeast phosphoglycerate kinase : which domain is more stable?},
  year      = {1995},
  language  = {en}
}
@article{DamaschunDamaschunGastetal.1993,
  author    = {Damaschun, Gregor and Damaschun, Hilde and Gast, Klaus and Misselwitz, Rolf and M{\"u}ller, J{\"u}rgen J. and Pfeil, Wolfgang and Zirwer, Dietrich},
  title     = {Cold denaturation-induced conformational changes in phosphoglycerate kinase from yeast},
  year      = {1993},
  language  = {en}
}
@misc{BestZhengBorgiaetal.2018,
  author    = {Best, Robert B. and Zheng, Wenwei and Borgia, Alessandro and Buholzer, Karin and Borgia, Madeleine B. and Hofmann, Hagen and Soranno, Andrea and Nettels, Daniel and Gast, Klaus and Grishaev, Alexander and Schuler, Benjamin},
  title     = {Comment on "Innovative scattering analysis shows that hydrophobic disordered proteins are expanded in water"},
  series = {Science},
  volume    = {361},
  journal   = {Science},
  number    = {6405},
  publisher = {American Assoc. for the Advancement of Science},
  address   = {Washington},
  issn      = {0036-8075},
  doi       = {10.1126/science.aar7101},
  pages     = {2},
  year      = {2018},
  abstract  = {Riback et al. (Reports, 13 October 2017, p. 238) used small-angle x-ray scattering (SAXS) experiments to infer a degree of compaction for unfolded proteins in water versus chemical denaturant that is highly consistent with the results from Forster resonance energy transfer (FRET) experiments. There is thus no "contradiction" between the two methods, nor evidence to support their claim that commonly used FRET fluorophores cause protein compaction.},
  language  = {en}
}
@article{BorgiaZhengBuholzeretal.2016,
  author    = {Borgia, Alessandro and Zheng, Wenwei and Buholzer, Karin and Borgia, Madeleine B. and Sch{\"u}ler, Anja and Hofmann, Hagen and Soranno, Andrea and Nettels, Daniel and Gast, Klaus and Grishaev, Alexander and Best, Robert B. and Schuler, Benjamin},
  title     = {Consistent View of Polypeptide Chain Expansion in Chemical Denaturants from Multiple Experimental Methods},
  series = {Journal of the American Chemical Society},
  volume    = {138},
  journal   = {Journal of the American Chemical Society},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0002-7863},
  doi       = {10.1021/jacs.6b05917},
  pages     = {11714 -- 11726},
  year      = {2016},
  abstract  = {There has been a long-standing controversy regarding the effect of chemical denaturants on the dimensions of unfolded and intrinsically disordered proteins: A wide range of experimental techniques suggest that polypeptide chains expand with increasing denaturant concentration, but several studies using small-angle X-ray scattering (SAXS) have reported no: such increase of the radius of gyration (R-g). This inconsistency challenges our current understanding of the mechanism of chemical denaturants, which are widely employed to investigate protein folding and stability. Here, we use a combination Of single-molecule Forster resonance energy transfer (FRET), SAXS, dynamic light scattering (DLS), and two-focus fluorescence correlation spectroscopy (2f-FCS) to characterize the denaturant dependence of the unfolded state of the spectrin domain R17 and the intrinsically disordered protein ACTR in two different denaturants. Standard analysis of the primary data clearly indicates an expansion of the unfolded state with increasing denaturant concentration irrespective of the protein, denaturant, or experimental method used. This is the first case in which SAXS and FRET have yielded even qualitatively consistent results regarding expansion in denaturant when applied to the same proteins. To more directly illustrate this self-consistency, we used both SAXS and FRET data in a Bayesian procedure to refine structural ensembles representative of the observed unfolded state. This analysis demonstrates that both of these experimental probes are compatible with a common ensemble of protein configurations for each denaturant concentration. Furthermore, the resulting ensembles reproduce the trend of increasing hydrodynamic radius, with denaturant concentration obtained by 2f-FCS,and DLS. We were thus able to reconcile the results from all four experimental techniques quantitatively, to obtain a comprehensive structural picture of denaturant;induced unfolded state expansion, and to identify the Most likely sources of earlier discrepancies.},
  language  = {en}
}
@article{Gast2010,
  author    = {Gast, Klaus},
  title     = {Dynamic and static light scattering},
  isbn      = {978-0-470-34341-8},
  year      = {2010},
  language  = {en}
}
@article{GastModler2007,
  author    = {Gast, Klaus and Modler, Andreas Johannes},
  title     = {Dynamic and static light scattering of proteins},
  isbn      = {978-1-600-21704-3},
  year      = {2007},
  language  = {en}
}
@article{FabianGastLaueetal.2008,
  author    = {Fabian, Heinz and Gast, Klaus and Laue, Michael and Misselwitz, Rolf and Uchanska-Ziegler, Barbara and Ziegler, Andreas and Naumann, Dieter},
  title     = {Early stages of misfolding and association of beta2-microglobulin : insights from infrared spectroscopy and dynamic light scattering},
  year      = {2008},
  abstract  = {Conformational changes associated with the assembly of recombinant ;2-microglobulin in vitro under acidic conditions were investigated using infrared spectroscopy and static and dynamic light scattering. In parallel, the morphology of the different aggregated species obtained under defined conditions was characterized by electron microscopy. The initial salt-induced aggregate form of ;2-microglobulin, composed of small oligomers (dimers to tetramers), revealed the presence of ;-strands organized in an intramolecular-like fashion. Further particle growth was accompanied by the formation of intermolecular ;-sheet structure and led to short curved forms. An increase in temperature by only 25 °C was able to disaggregate these assemblies, followed by the formation of longer filamentous structures. In contrast, a rise in temperature up to 100 °C was associated with a reorganization of the short curved forms at the level of secondary structure and the state of assembly, leading to a species with a characteristic infrared spectrum different from those of all the other aggregates observed before, suggesting a unique overall structure. The infrared spectral features of this species were nearly identical to those of ;2-microglobulin assemblies formed at low ionic strength with agitation, indicating the presence of fibrils, which was confirmed by electron microscopy. The observed spectroscopic changes suggest that the heat-triggered conversion of the short curved assemblies into fibrils involves a reorganization of the ;-strands from an antiparallel arrangement to a parallel arrangement, with the latter being characteristic of amyloid fibrils of ;2-microglobulin.},
  language  = {en}
}
@article{HerbstGastSeckler1998,
  author    = {Herbst, R. and Gast, Klaus and Seckler, Robert},
  title     = {Folding of firefly (Photinus pyralis) luciferase : aggregation and reactivation of unfolding intermediates},
  year      = {1998},
  language  = {en}
}
@article{ReschkeSigfridssonKaufmannetal.2013,
  author    = {Reschke, Stefan and Sigfridsson, Kajsa G. V. and Kaufmann, Paul and Leidel, Nils and Horn, Sebastian and Gast, Klaus and Schulzke, Carola and Haumann, Michael and Leimk{\"u}hler, Silke},
  title     = {Identification of a bis-molybdopterin intermediate in molybdenum cofactor biosynthesis in escherichia coli},
  series = {The journal of biological chemistry},
  volume    = {288},
  journal   = {The journal of biological chemistry},
  number    = {41},
  publisher = {American Society for Biochemistry and Molecular Biology},
  address   = {Bethesda},
  issn      = {0021-9258},
  doi       = {10.1074/jbc.M113.497453},
  pages     = {29736 -- 29745},
  year      = {2013},
  abstract  = {The molybdenum cofactor is an important cofactor, and its biosynthesis is essential for many organisms, including humans. Its basic form comprises a single molybdopterin (MPT) unit, which binds a molybdenum ion bearing three oxygen ligands via a dithiolene function, thus forming Mo-MPT. In bacteria, this form is modified to form the bis-MPT guanine dinucleotide cofactor with two MPT units coordinated at one molybdenum atom, which additionally contains GMPs bound to the terminal phosphate group of the MPTs (bis-MGD). The MobA protein catalyzes the nucleotide addition to MPT, but the mechanism of the biosynthesis of the bis-MGD cofactor has remained enigmatic. We have established an in vitro system for studying bis-MGD assembly using purified compounds. Quantification of the MPT/molybdenum and molybdenum/phosphorus ratios, time-dependent assays for MPT and MGD detection, and determination of the numbers and lengths of Mo-S and Mo-O bonds by X-ray absorption spectroscopy enabled identification of a novel bis-Mo-MPT intermediate on MobA prior to nucleotide attachment. The addition of Mg-GTP to MobA loaded with bis-Mo-MPT resulted in formation and release of the final bis-MGD product. This cofactor was fully functional and reconstituted the catalytic activity of apo-TMAO reductase (TorA). We propose a reaction sequence for bis-MGD formation, which involves 1) the formation of bis-Mo-MPT, 2) the addition of two GMP units to form bis-MGD on MobA, and 3) the release and transfer of the mature cofactor to the target protein TorA, in a reaction that is supported by the specific chaperone TorD, resulting in an active molybdoenzyme.},
  language  = {en}
}
@article{PiontekWinklerBaletal.2004,
  author    = {Piontek, J. and Winkler, Lars and Bal, M. S. and Lassowski, Birgit and Mueller, Sandra L. and Gast, Klaus and Blasig, Ingolf E.},
  title     = {Investigating of homophilic interactions of the tight junction proteins occludin and claudin-5},
  year      = {2004},
  language  = {en}
}
@article{FabianGastLaueetal.2013,
  author    = {Fabian, Heinz and Gast, Klaus and Laue, Michael and Jetzschmann, Katharina J. and Naumann, Dieter and Ziegler, Andreas and Uchanska-Ziegler, Barbara},
  title     = {IR spectroscopic analyses of amyloid fibril formation of beta(2)-microglobulin using a simplified procedure for its in vitro generation at neutral pH},
  series = {Biophysical chemistry : an international journal devoted to the physical chemistry of biological phenomena},
  volume    = {179},
  journal   = {Biophysical chemistry : an international journal devoted to the physical chemistry of biological phenomena},
  number    = {5},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0301-4622},
  doi       = {10.1016/j.bpc.2013.05.001},
  pages     = {35 -- 46},
  year      = {2013},
  abstract  = {beta(2)-microglobulin (beta(2)m) is known to be the major component of fibrillar deposits in the joints of patients suffering from dialysis-related amyloidosis. We have developed a simplified procedure to convert monomeric recombinant beta(2)m into amyloid fibrils at physiological pH by a combination of stirring and heating, enabling us to follow conformational changes associated with the assembly by infrared spectroscopy and electron microscopy. Our studies reveal that fibrillogenesis begins with the formation of relatively large aggregates, with secondary structure not significantly altered by the stirring-induced association. In contrast, the conversion of the amorphous aggregates into amyloid fibrils is associated with a profound re-organization at the level of the secondary and tertiary structures, leading to non-native like parallel arrangements of the beta-strands in the fully formed amyloid structure of beta(2)m. This study highlights the power of an approach to investigate the formation of beta(2)m fibrils by a combination of biophysical techniques including IR spectroscopy.},
  language  = {en}
}
@article{KellerSauerStraussetal.2005,
  author    = {Keller, S. and Sauer, I. and Strauss, H. and Gast, Klaus and Dathe, M. and Bienert, Michael C.},
  title     = {Membrane-mimetic nanocarriers formed by a dipalmitoylated cell-penetrating peptide},
  year      = {2005},
  language  = {en}
}
@article{BlasigWinklerLassowskietal.2006,
  author    = {Blasig, Ingolf E. and Winkler, Lars and Lassowski, Birgit and M{\"u}ller, Sandra L. and Zuleger, Nikolaj and Krause, Eberhard and Krause, Gerd and Gast, Klaus and Kolbe, Michael and Piontek, J{\"o}rg},
  title     = {On the self-association potential of transmembrane tight junction proteins},
  issn      = {1420-682X},
  doi       = {10.1007/s00018-005-5472-x},
  year      = {2006},
  abstract  = {Tight junctions seal intercellular clefts via membrane-related strands, hence, maintaining important organ functions. We investigated the self-association of strand-forming transmembrane tight junction proteins. The regulatory tight junction protein occludin was differently tagged and cotransfected in eucaryotic cells. These occludins colocalized within the plasma membrane of the same cell, coprecipitated and exhibited fluorescence resonance energy transfer. Differently tagged strand-forming claudin-5 also colocalized in the plasma membrane of the same cell and showed fluorescence resonance energy transfer. This demonstrates self-association in intact cells both of occludin and claudin-5 in one plasma membrane. In search of dimerizing regions of occludin, dimerization of its cytosolic C-terminal coiled-coil domain was identified. In claudin-5, the second extracellular loop was detected as a dimer. Since the transmembrane junctional adhesion molecule also is known to dimerize, the assumption that homodimerization of transmembrane tight junction proteins may serve as a common structural feature in tight junction assembly is supported},
  language  = {en}
}
@article{HofmannSorannoBorgiaetal.2012,
  author    = {Hofmann, Hagen and Soranno, Andrea and Borgia, Alessandro and Gast, Klaus and Nettels, Daniel and Schuler, Benjamin},
  title     = {Polymer scaling laws of unfolded and intrinsically disordered proteins quantified with single-molecule spectroscopy},
  series = {Proceedings of the National Academy of Sciences of the United States of America},
  volume    = {109},
  journal   = {Proceedings of the National Academy of Sciences of the United States of America},
  number    = {40},
  publisher = {National Acad. of Sciences},
  address   = {Washington},
  issn      = {0027-8424},
  doi       = {10.1073/pnas.1207719109},
  pages     = {16155 -- 16160},
  year      = {2012},
  abstract  = {The dimensions of unfolded and intrinsically disordered proteins are highly dependent on their amino acid composition and solution conditions, especially salt and denaturant concentration. However, the quantitative implications of this behavior have remained unclear, largely because the effective theta-state, the central reference point for the underlying polymer collapse transition, has eluded experimental determination. Here, we used single-molecule fluorescence spectroscopy and two-focus correlation spectroscopy to determine the theta points for six different proteins. While the scaling exponents of all proteins converge to 0.62 +/- 0.03 at high denaturant concentrations, as expected for a polymer in good solvent, the scaling regime in water strongly depends on sequence composition. The resulting average scaling exponent of 0.46 +/- 0.05 for the four foldable protein sequences in our study suggests that the aqueous cellular milieu is close to effective theta conditions for unfolded proteins. In contrast, two intrinsically disordered proteins do not reach the T-point under any of our solvent conditions, which may reflect the optimization of their expanded state for the interactions with cellular partners. Sequence analyses based on our results imply that foldable sequences with more compact unfolded states are a more recent result of protein evolution.},
  language  = {en}
}
@article{ModlerFabianSokolowskietal.2004,
  author    = {Modler, Andreas Johannes and Fabian, H. and Sokolowski, F. and Lutsch, G. and Gast, Klaus and Damaschun, Gregor},
  title     = {Polymerization of proteins into amyloid protofibrils shares common critical oligomeric states but differs in the mechanisms of their formation},
  year      = {2004},
  abstract  = {Amyloid protofibril formation of phosphoglycerate kinase (PGK) and Syrian hamster prion protein (SHaPrP(90- 232)) were investigated by static and dynamic light scattering, size exclusion chromatography and electron microscopy. Changes in secondary structure were monitored by Fourier transform infrared spectroscopy and by circular dichroism. Protofibril formation of the two proteins is found to be a two-stage process. At the beginning, an ensemble of critical oligomers is built lip. These critical oligomeric states possess a predominant beta-sheet structure and do not interact considerably with monomers. Initial oligomerization and transition to beta-sheet structure are coupled events differing in their details for both proteins. Intermediate oligomeric states (dimers, trimers, etc.) are populated in case of PGK, whereas SHaPrP(90-232) behaves according to oil apparent two-state reaction between monomers and octamers rich in beta- structure with a reaction order varying between 2 and 4. All oligomers coalesce to PGK protofibrils in the second stage, while SHaPrP(90-232) protofibrils are only formed by a subpopulation. The rates of both growth stages can be tuned in case of PGK by different salts preserving the underlying generalized diffusion-collision mechanism. The different kinetics of the early misfolding and oligomerization events of the two proteins argue against a common mechanism of protofibril formation. A classification scheme for misassembly, mechanisms of proteins based on energy landscapes is presented. It includes scenarios of downhill polymerization to which protofibril formation of PGK and SHaPrP(90-232) belong},
  language  = {en}
}
@article{GastSchuelerWolffetal.2017,
  author    = {Gast, Klaus and Sch{\"u}ler, Anja and Wolff, Martin and Thalhammer, Anja and Berchtold, Harald and Nagel, Norbert and Lenherr, Gudrun and Hauck, Gerrit and Seckler, Robert},
  title     = {Rapid-acting and human insulins},
  series = {Pharmaceutical research},
  volume    = {34},
  journal   = {Pharmaceutical research},
  number    = {795},
  publisher = {Springer},
  address   = {New York},
  issn      = {0724-8741},
  doi       = {10.1007/s11095-017-2233-0},
  pages     = {2270 -- 2286},
  year      = {2017},
  abstract  = {Comparison of the dissociation kinetics of rapid-acting insulins lispro, aspart, glulisine and human insulin under physiologically relevant conditions. Dissociation kinetics after dilution were monitored directly in terms of the average molecular mass using combined static and dynamic light scattering. Changes in tertiary structure were detected by near-UV circular dichroism. Glulisine forms compact hexamers in formulation even in the absence of Zn2+. Upon severe dilution, these rapidly dissociate into monomers in less than 10 s. In contrast, in formulations of lispro and aspart, the presence of Zn2+ and phenolic compounds is essential for formation of compact R6 hexamers. These slowly dissociate in times ranging from seconds to one hour depending on the concentration of phenolic additives. The disadvantage of the long dissociation times of lispro and aspart can be diminished by a rapid depletion of the concentration of phenolic additives independent of the insulin dilution. This is especially important in conditions similar to those after subcutaneous injection, where only minor dilution of the insulins occurs. Knowledge of the diverging dissociation mechanisms of lispro and aspart compared to glulisine will be helpful for optimizing formulation conditions of rapid-acting insulins.},
  language  = {en}
}
@misc{GastSchuelerWolffetal.2017,
  author    = {Gast, Klaus and Sch{\"u}ler, Anja and Wolff, Martin and Thalhammer, Anja and Berchtold, Harald and Nagel, Norbert and Lenherr, Gudrun and Hauck, Gerrit and Seckler, Robert},
  title     = {Rapid-acting and human insulins},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {795},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43157},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-431572},
  pages     = {2270 -- 2286},
  year      = {2017},
  abstract  = {Purpose: Comparison of the dissociation kinetics of rapid-acting insulins lispro, aspart, glulisine and human insulin under physiologically relevant conditions. Methods: Dissociation kinetics after dilution were monitored directly in terms of the average molecular mass using combined static and dynamic light scattering. Changes in tertiary structure were detected by near-UV circular dichroism. Results: Glulisine forms compact hexamers in formulation even in the absence of Zn2+. Upon severe dilution, these rapidly dissociate into monomers in less than 10 s. In contrast, in formulations of lispro and aspart, the presence of Zn2+ and phenolic compounds is essential for formation of compact R6 hexamers. These slowly dissociate in times ranging from seconds to one hour depending on the concentration of phenolic additives. The disadvantage of the long dissociation times of lispro and aspart can be diminished by a rapid depletion of the concentration of phenolic additives independent of the insulin dilution. This is especially important in conditions similar to those after subcutaneous injection, where only minor dilution of the insulins occurs. Conclusion: Knowledge of the diverging dissociation mechanisms of lispro and aspart compared to glulisine will be helpful for optimizing formulation conditions of rapid-acting insulins.},
  language  = {en}
}
@article{WalterCastroVossetal.2009,
  author    = {Walter, Juliane K. and Castro, Victor Manuel and Voss, M. and Gast, Klaus and Rueckert, C. and Piontek, J. and Blasig, Ingolf E.},
  title     = {Redox sensitivity of the dimerization of occludin},
  issn      = {1420-682X},
  year      = {2009},
  abstract  = {Occludin is a self-associating transmembrane tight junction protein affected in oxidative stress. However, its function is unknown. The cytosolic C-terminal tail contains a coiled coil-domain forming dimers contributing to the self- association. Studying the hypothesis that the self-association is redox-sensitive, we found that the dimerization of the domain depended on the sulfhydryl concentration of the environment in low-millimolar range. Under physiological conditions, monomers and dimers were detected. Masking the sulfhydryl residues in the domain prevented the dimerization but affected neither its helical structure nor cylindric shape. Incubation of cell extracts containing full-length occludin with sulfhydryl reagents prevented the dimerization; a cysteine/alanine exchange mutant also did not show dimer formation. This demonstrates, for the first time, that disulfide bridge formation of the domain is involved in the occludin dimerization. It is concluded that the redox-dependent dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions.},
  language  = {en}
}