Structural changes accompanying chloroform-induced contraction of the filamentous phage fd

Linda M. Roberts, A. Dunker

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Contact with a chloroform/water interface at 2°C induces contraction of fd filamentous phage into rodlike I-forms; this contraction is accompanied by a decrease in the magnitude of circular dichroism spectral intensity near 222 nm and an increase near 210 nm. Comparisons with circular dichroism spectra of 100% helical poly-L-lysine and N-bromosuccinimide-oxidized fd phage indicate that the spectral change accompanying the fd to I-forms transition is due primarily to a change in the contributions from the single tryptophan (W26) of the major coat protein, with probably no significant change in the α-helix content. Further contraction of the rodlike I-forms to spherical S-forms at 25°C is accompanied by a substantial general decrease in the magnitude of the ellipticity throughout the 230-210-nm region, which is indicative of a decrease in the α-helix content of the major coat protein. The similarity of the circular dichroism spectrum of S-forms with that of coat protein in detergents suggests that the S-form coat protein resembles the coat protein in lipid bilayers. The intrinsic fluorescence of W26 is quenched without red-shift (but perhaps a barely detectable blue-shift) following fd contraction to I-forms and S-forms. The accessibility of W26 to aqueous quenchers does not change significantly upon contraction. However, interaction with hydrophobic quenchers is dramatically altered in the contracted forms in a manner suggesting that the environment surrounding the tryptophan changes from native-protein-like in the fd filament to molten globule-like in the I-form rods and S-form spheroids. As discussed herein, certain features of these data support previous suggestions that chloroform-induced filamentous phage contraction may provide information about phage penetration and assembly in vivo.

Original languageEnglish (US)
Pages (from-to)10479-10488
Number of pages10
JournalBiochemistry
Volume32
Issue number39
StatePublished - 1993
Externally publishedYes

Fingerprint

Bacteriophage M13
Bacteriophages
Capsid Proteins
Chloroform
Circular Dichroism
Tryptophan
Bromosuccinimide
Lipid Bilayers
Lipid bilayers
Hydrophobic and Hydrophilic Interactions
Detergents
Lysine
Fluorescence
Molten materials
Water
Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Structural changes accompanying chloroform-induced contraction of the filamentous phage fd. / Roberts, Linda M.; Dunker, A.

In: Biochemistry, Vol. 32, No. 39, 1993, p. 10479-10488.

Research output: Contribution to journalArticle

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