SDS-Facilitated In vitro Formation of a Transmembrane B-Type Cytochrome Is Mediated by Changes in Local pH

Weber, Mathias; Prodöhl, Alexander; Dreher, Carolin; Becker, Christian F. W.; Underhaug, Jarl; Svane, Anna S.P.; Malmendal, Anders; Nielsen, Niels Chr.; Otzen, Daniel E.; Schneider, Dirk

doi:10.1016/j.jmb.2011.02.005

Cited by 17 publications

(9 citation statements)

References 43 publications

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“…Detergents are commonly used to solubilise and sometimes deactivate membrane proteins (Seddon et al 2004). Furthermore, heme b has been observed to dissociate from cytochrome b 559 , the heterodimer of the PsbE and PsbF subunits of PSII, in non-ionic detergents at pH 10 (Weber et al 2011). Clearly, heme b proteins are differentially extracted in ammoniacal detergent, and it is possible that the different extraction efficiencies relate to protein solubility or the heme ligand environment within the protein (Weber et al 2011).…”

Section: Discussionmentioning

confidence: 99%

Heme b in marine phytoplankton and particulate material from the North Atlantic Ocean

Honey¹,

Gledhill²,

Bibby³

et al. 2013

Mar. Ecol. Prog. Ser.

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Section: Discussionmentioning

confidence: 99%

Heme b in marine phytoplankton and particulate material from the North Atlantic Ocean

Honey¹,

Gledhill²,

Bibby³

et al. 2013

Mar. Ecol. Prog. Ser.

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“…Although the reaction heats could be fitted on the basis of the regular mixing model at intermediate SDS contents in the mixed aggregates [13] , such fits yielded very high nonideality parameters of 3–4 RT , which is incompatible with the near-ideal mixing assumption inherent in this model. At both lower and higher SDS concentrations, the isotherms could not at all be analyzed in terms of simple mixing models, which is most likely due to a charge repulsion between free SDS monomers and mixed APol/SDS aggregates or due to the changes in pH at the surface of the mixed aggregate [46] , [47] . Thus, care should be taken in interpreting SDS titration data involving anionic APols at a quantitative level, which is why we restrict ourselves to qualitative considerations in the following.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, addition of SDS to APol-reconstituted GpA TM peptides below the CMC of SDS appears to dramatically destabilize the GpA dimer, which might be caused by the altered structure of the APol aggregate, and thus the altered local environment of the GpA TM helix dimer. Furthermore, addition of extra negative charges might result in increased electrostatic interactions of a stretch of positive charges in the GpA juxtamembrane region, which could destabilize the helix dimer [49] , or in an more acidic local pH at the surface of the mixed aggregate [46] . Nevertheless, since mixing of APol and SDS is strongly non-ideal, further analyses are needed for a more detailed, quantitative treatment.…”

Section: Resultsmentioning

confidence: 99%

Sequence-Specific Dimerization of a Transmembrane Helix in Amphipol A8-35

et al. 2014

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As traditional detergents might destabilize or even denature membrane proteins, amphiphilic polymers have moved into the focus of membrane-protein research in recent years. Thus far, Amphipols are the best studied amphiphilic copolymers, having a hydrophilic backbone with short hydrophobic chains. However, since stabilizing as well as destabilizing effects of the Amphipol belt on the structure of membrane proteins have been described, we systematically analyze the impact of the most commonly used Amphipol A8-35 on the structure and stability of a well-defined transmembrane protein model, the glycophorin A transmembrane helix dimer. Amphipols are not able to directly extract proteins from their native membranes, and detergents are typically replaced by Amphipols only after protein extraction from membranes. As Amphipols form mixed micelles with detergents, a better understanding of Amphipol-detergent interactions is required. Therefore, we analyze the interaction of A8-35 with the anionic detergent sodium dodecyl sulfate and describe the impact of the mixed-micelle-like system on the stability of a transmembrane helix dimer. As A8-35 may highly stabilize and thereby rigidify a transmembrane protein structure, modest destabilization by controlled addition of detergents and formation of mixed micellar systems might be helpful to preserve the function of a membrane protein in Amphipol environments.

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“…As the TM regions of PsbE and PsbF are well conserved, a cytochrome b 559 -like structure (cytochrome b 559 0 ) can be formed in vitro solely from the PsbF subunit, which forms a heme-binding TM helix dimer [31]. Dimerization and heme binding of cytochrome b 559 0 has already been analyzed to some extent and few amino acids crucial for heme binding or dimerization have already been identified [32][33][34]. A highly conserved glycine residue in the dimerization domain has been shown to be crucial for dimerization and holo-cytochrome formation [31].…”

Section: Introductionmentioning

confidence: 99%

Six amino acids define a minimal dimerization sequence and stabilize a transmembrane helix dimer by close packing and hydrogen bonding

Weber

Schneider

2013

FEBS Letters

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Edited by Richard CogdellKeywords: Cytochrome b 559 Dimerization motif Transmembrane Helix-helix interaction Sequence context a b s t r a c t Distinct amino acid sequences have been described to mediate oligomerization of transmembrane a-helices. However, as the sequence context is crucial to determine specificity in transmembrane helix-helix interaction, the question arises how small a sequence can be without losing specificity. In the present analysis, six amino acids have been identified in the PsbF transmembrane helix dimer, which form the contact region of two interacting helices and are directly involved in helix-helix interactions. However, individual amino acids within the complex sequence pattern only together ensure sequence specificity of the analyzed transmembrane helix-helix interactions by mediating close packing and inter-helical hydrogen bonding. Structured summary of protein interactions:psbF and psbF physically interact by lex-a dimerization assay (View Interaction: 1,2,3,4,5)

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SDS-Facilitated In vitro Formation of a Transmembrane B-Type Cytochrome Is Mediated by Changes in Local pH

Cited by 17 publications

References 43 publications

Heme b in marine phytoplankton and particulate material from the North Atlantic Ocean

Heme b in marine phytoplankton and particulate material from the North Atlantic Ocean

Sequence-Specific Dimerization of a Transmembrane Helix in Amphipol A8-35

Six amino acids define a minimal dimerization sequence and stabilize a transmembrane helix dimer by close packing and hydrogen bonding

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