Hostname: page-component-78c5997874-94fs2 Total loading time: 0 Render date: 2024-11-05T22:33:57.324Z Has data issue: false hasContentIssue false

Folding of apocytochrome c induced by the interaction with negatively charged lipid micelles proceeds via a collapsed intermediate state

Published online by Cambridge University Press:  01 February 1999

SAFFRON E. RANKIN
Affiliation:
Department of Biological Sciences, Gibbet Hill Road, University of Warwick, Coventry CV4 7AL, United Kingdom
ANTHONY WATTS
Affiliation:
Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
HEINRICH RODER
Affiliation:
Institute for Cancer Research, Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, Pennsylvania 19111
TERESA J.T. PINHEIRO
Affiliation:
Department of Biological Sciences, Gibbet Hill Road, University of Warwick, Coventry CV4 7AL, United Kingdom
Get access

Abstract

Unfolded apocytochrome c acquires an α-helical conformation upon interaction with lipid. Folding kinetic results below and above the lipid's CMC, together with energy transfer measurements of lipid bound states, and salt-induced compact states in solution, show that the folding transition of apocytochrome c from the unfolded state in solution to a lipid-inserted helical conformation proceeds via a collapsed intermediate state (IC). This initial compact state is driven by a hydrophobic collapse of the polypeptide chain in the absence of the heme group and may represent a heme-free analogue of an early compact intermediate detected on the folding pathway of cytochrome c in solution. Insertion into the lipid phase occurs via an unfolding step of IC through a more extended state associated with the membrane surface (IS). While IC appears to be as compact as salt-induced compact states in solution with substantial α-helix content, the final lipid-inserted state (Hmic) is as compact as the unfolded state in solution at pH 5 and has an α-helix content which resembles that of native cytochrome c.

Type
Research Article
Copyright
© 1999 The Protein Society

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)