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An environment-dependent structural switch underlies the regulation of carnitine palmitoyltransferase 1A.


ABSTRACT: The enzyme carnitine palmitoyltransferase 1 (CPT1), which is anchored in the outer mitochondrial membrane (OMM), controls the rate-limiting step in fatty acid ?-oxidation in mammalian tissues. It is inhibited by malonyl-CoA, the first intermediate of fatty acid synthesis, and it responds to OMM curvature and lipid characteristics, which reflect long term nutrient/hormone availability. Here, we show that the N-terminal regulatory domain (N) of CPT1A can adopt two complex amphiphilic structural states, termed N? and N?, that interchange in a switch-like manner in response to offered binding surface curvature. Structure-based site-directed mutageneses of native CPT1A suggest N? to be inhibitory and N? to be noninhibitory, with the relative N?/N? ratio setting the prevalent malonyl-CoA sensitivity of the enzyme. Based on the amphiphilic nature of N and molecular modeling, we propose malonyl-CoA sensitivity to be coupled to the properties of the OMM by N?-OMM associations that alter the N?/N? ratio. For enzymes residing at the membrane-water interface, this constitutes an integrative regulatory mechanism of exceptional sophistication.

SUBMITTER: Rao JN 

PROVIDER: S-EPMC3234983 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature

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An environment-dependent structural switch underlies the regulation of carnitine palmitoyltransferase 1A.

Rao Jampani N JN   Warren Gemma Z L GZL   Estolt-Povedano Sara S   Zammit Victor A VA   Ulmer Tobias S TS  

The Journal of biological chemistry 20111011 49


The enzyme carnitine palmitoyltransferase 1 (CPT1), which is anchored in the outer mitochondrial membrane (OMM), controls the rate-limiting step in fatty acid β-oxidation in mammalian tissues. It is inhibited by malonyl-CoA, the first intermediate of fatty acid synthesis, and it responds to OMM curvature and lipid characteristics, which reflect long term nutrient/hormone availability. Here, we show that the N-terminal regulatory domain (N) of CPT1A can adopt two complex amphiphilic structural st  ...[more]

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