Formation of non-beta 6.3-helical gramicidin channels between sequence-substituted gramicidin analogues.

Using the linear gramicidins as an example, we have previously shown how the statistical properties of heterodimeric (hybrid) channels (formed between the parent [Val1]gramicidin A (gA) and a sequence-altered analogue) can be used to assess whether the analogue forms channels that are structurally e...

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Autores principales: Durkin, J T, Providence, L L, Koeppe, R E, Andersen, O S
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Lenguaje:English
Publicado: 1992
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Research Article
Acceso en línea:https://ncbi.nlm.nih.gov/pmc/articles/PMC1260509/
https://ncbi.nlm.nih.gov/pubmed/1376164
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spelling pubmed-12605092006-01-17 Formation of non-beta 6.3-helical gramicidin channels between sequence-substituted gramicidin analogues. Durkin, J T Providence, L L Koeppe, R E Andersen, O S Biophys J Research Article Using the linear gramicidins as an example, we have previously shown how the statistical properties of heterodimeric (hybrid) channels (formed between the parent [Val1]gramicidin A (gA) and a sequence-altered analogue) can be used to assess whether the analogue forms channels that are structurally equivalent to the parent channels (Durkin, J. T., R. E. Koeppe II, and O. S. Andersen. 1990. J. Mol. Biol. 211:221-234). Generally, the gramicidins are tolerant of amino acid sequence alterations. We report here an exception. The optically reversed analogue, gramicidin M- (gM-) (Heitz, F., G. Spach, and Y. Trudelle. 1982. Biophys. J. 40:87-89), forms channels that are the mirror-image of [Val1]gA channels; gM- should thus form no hybrid channels with analogues having the same helix sense as [Val1]gA. Surprisingly, however, gM- forms hybrid channels with the shortened analogues des-Val1-[Ala2]gA and des-Val1-gC, but these channels differ fundamentally from the parent channels: (a) the appearance rate of these heterodimers is only approximately 1/10 of that predicted from the random assortment of monomers into conducting dimers, indicating the existence of an energy barrier to their formation (e.g., monomer refolding into a new channel-forming conformation); and (b), once formed, the hybrid channels are stabilized approximately 1,000-fold relative to the parent channels. The increased stability suggests a structure that is joined by many hydrogen bonds, such as one of the double-stranded helical dimers shown to be adopted by gramicidins in organic solvents (Veatch, W. R., E. T. Fossel, and E. R. Blout. 1974. Biochemistry. 13:5249-5256). 1992-04 /pmc/articles/PMC1260509/ /pubmed/1376164 Text en
institution US National Library of Medicine
collection PubMed Central
language English
format Article
topic Research Article
spellingShingle Research Article
Durkin, J T
Providence, L L
Koeppe, R E
Andersen, O S
Formation of non-beta 6.3-helical gramicidin channels between sequence-substituted gramicidin analogues.
description Using the linear gramicidins as an example, we have previously shown how the statistical properties of heterodimeric (hybrid) channels (formed between the parent [Val1]gramicidin A (gA) and a sequence-altered analogue) can be used to assess whether the analogue forms channels that are structurally equivalent to the parent channels (Durkin, J. T., R. E. Koeppe II, and O. S. Andersen. 1990. J. Mol. Biol. 211:221-234). Generally, the gramicidins are tolerant of amino acid sequence alterations. We report here an exception. The optically reversed analogue, gramicidin M- (gM-) (Heitz, F., G. Spach, and Y. Trudelle. 1982. Biophys. J. 40:87-89), forms channels that are the mirror-image of [Val1]gA channels; gM- should thus form no hybrid channels with analogues having the same helix sense as [Val1]gA. Surprisingly, however, gM- forms hybrid channels with the shortened analogues des-Val1-[Ala2]gA and des-Val1-gC, but these channels differ fundamentally from the parent channels: (a) the appearance rate of these heterodimers is only approximately 1/10 of that predicted from the random assortment of monomers into conducting dimers, indicating the existence of an energy barrier to their formation (e.g., monomer refolding into a new channel-forming conformation); and (b), once formed, the hybrid channels are stabilized approximately 1,000-fold relative to the parent channels. The increased stability suggests a structure that is joined by many hydrogen bonds, such as one of the double-stranded helical dimers shown to be adopted by gramicidins in organic solvents (Veatch, W. R., E. T. Fossel, and E. R. Blout. 1974. Biochemistry. 13:5249-5256).
author Durkin, J T
Providence, L L
Koeppe, R E
Andersen, O S
author_facet Durkin, J T
Providence, L L
Koeppe, R E
Andersen, O S
author_sort Durkin, J T
title Formation of non-beta 6.3-helical gramicidin channels between sequence-substituted gramicidin analogues.
title_short Formation of non-beta 6.3-helical gramicidin channels between sequence-substituted gramicidin analogues.
title_full Formation of non-beta 6.3-helical gramicidin channels between sequence-substituted gramicidin analogues.
title_fullStr Formation of non-beta 6.3-helical gramicidin channels between sequence-substituted gramicidin analogues.
title_full_unstemmed Formation of non-beta 6.3-helical gramicidin channels between sequence-substituted gramicidin analogues.
title_sort formation of non-beta 6.3-helical gramicidin channels between sequence-substituted gramicidin analogues.
publishDate 1992
url https://ncbi.nlm.nih.gov/pmc/articles/PMC1260509/
https://ncbi.nlm.nih.gov/pubmed/1376164
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