Structural and functional organization of the animal fatty acid synthase

doi:10.1016/S0163-7827(02)00067-X

Progress in Lipid Research

Volume 42, Issue 4, July 2003, Pages 289-317

https://doi.org/10.1016/S0163-7827(02)00067-X Get rights and content

Abstract

The entire pathway of palmitate synthesis from malonyl-CoA in mammals is catalyzed by a single, homodimeric, multifunctional protein, the fatty acid synthase. Each subunit contains three N-terminal domains, the β-ketoacyl synthase, malonyl/acetyl transferase and dehydrase separated by a structural core from four C-terminal domains, the enoyl reductase, β-ketoacyl reductase, acyl carrier protein and thiosterase. The kinetics and specificities of the substrate loading reaction catalyzed by the malonyl/acetyl transferase, the condensation reaction catalyzed by β-ketoacyl synthase and chain-terminating reaction catalyzed by the thioesterase ensure that intermediates do not leak off the enzyme, saturated chains exclusively are elongated and palmitate is released as the major product. Only in the fatty acid synthase dimer do the subunits adopt conformations that facilitate productive coupling of the individual reactions for fatty acid synthesis at the two acyl carrier protein centers. Introduction of a double tagging and dual affinity chromatographic procedure has permitted the engineering and isolation of heterodimeric fatty acid synthases carrying different mutations on each subunit. Characterization of these heterodimers, by activity assays and chemical cross-linking, has been exploited to map the functional topology of the protein. The results reveal that the two acyl carrier protein domains engage in substrate loading and condensation reactions catalyzed by the malonyl/acetyl transferase and β-ketoacyl synthase domains of either subunit. In contrast, the reactions involved in processing of the β-carbon atom, following each chain elongation step, together with the release of palmitate, are catalyzed by the cooperation of the acyl carrier protein with catalytic domains of the same subunit. These findings suggest a revised model for the fatty acid synthase in which the two polypeptides are oriented such that head-to-tail contacts are formed both between and within subunits.

Section snippets

Historical perspective

Until the late 1950s it was generally assumed that fatty acid synthesis from acetyl-CoA proceeded by direct reversal of the mitochondrial β-oxidation pathway for the degradation of fatty acids to acetyl-CoA [1]. Although there had been two reports that CO₂ stimulated fatty acid biosynthesis in liver slice preparations [2] and in yeast [3], radioactive CO₂ was not incorporated into fatty acids [3] and the significance of these observations was not immediately appreciated. In 1958, Salih Wakil

The overall reaction sequence

The key feature of the pathway for biosynthesis of fatty acids de novo in animals is the sequential extension of an alkanoic chain, two carbons at a time, by a series of decarboxylative condensation reactions that can be summarized by the equation: $Acetyl-CoA+7 Malonyl-CoA+14 NADPH+14 H^{+} → Palmitic acid +7 CO_{2} +8 CoA+14 NADP^{+} +6 H_{2} O$

The process is initiated by the sequential transfer of a primer substrate, usually an acetyl moiety, from CoA thioester form, first to the nucleophilic serine residue

Substrate loading

Initiation of the series of condensation reactions leading to the production of palmitic acid requires the translocation of one acetyl and seven malonyl moieties, from CoA thioester to the phosphopantetheine thiol of the ACP domain. However, the FAS employs the same acyltransferase for loading both substrates and the process is not ordered in the sense that a single acetyl moiety is loaded first, followed by seven malonyl moieties. Rather, the process is entirely random and both substrates are

Domain map

The earliest attempts to generate a domain map of the FAS utilized limited proteolysis, under non-denaturing conditions, to dissect the multifunctional polypeptide into its individual components [80], [81], [82]. As the entire sequences of several animal FASs were deduced and some of the FAS domains were expressed as independent catalytically active proteins, a more detailed domain map began to emerge. Confirmation of the location of the various catalytic domains was eventually provided by

A revised model for the animal FAS

The new data discussed above necessitate substantial revision of the original head-to-tail model for the multifunctional FAS. A new model must satisfy the following requirements:

1.
The model should allow for physical and functional interactions across the subunit interface between the ACP of one subunit and the β̃-ketoacyl synthase and malonyl/acetyl transferase domains of the companion subunit, as envisioned in the original model
2.
The model should allow for functional interactions between domains

Perspective

The recently obtained data described in the previous section show clearly that each phosphopantetheine moiety is able to communicate functionally with eight catalytic domains, the dehydrase, enoyl reductase, β̃-ketoacyl reductase and thioesterase of the same subunit and the β̃-ketoacyl synthase and malonyl/acetyl transferase of both subunits. For many years, mobility of the 4′-phosphopantetheine ‘swinging arm’ was assumed to facilitate interaction with the various catalytic domains.

Acknowledgements

The work from our laboratory described in this article was supported by grant DK16073 from the National Institutes of Health. We thank Dr. Ylva Lindqvist for modeling the structure of the β-ketoacyl synthase domain of the FAS and Dr. James Stannton for his thoughtful discussion of the β-ketoacyl synthase reaction mechanism. We are grateful to Drs. Vangipuram S. Rangan and Katayoon Dehesh for their critical reading of the manuscript.

References (110)

F. Lynen et al.
Biochim Biophys Acta
(1953)
R.O. Brady et al.
J Biol Chem.
(1950)
D.M. Gibson et al.
Biochim Biophys Acta
(1958)
P.W. Majerus et al.
J Biol Chem.
(1965)
G. Weeks et al.
J Biol Chem.
(1968)
S. Kumar et al.
Biochem Biophys Res Comm.
(1970)
S.C. Bratcher et al.
Arch. Biochem. Biophys.
(1976)
F.A. Lornitzo et al.
J Biol Chem.
(1974)
A.A. Qureshi et al.
Biochem Biophys Res Comm.
(1975)
A.A. Qureshi et al.
Arch. Biochem. Biophys.
(1976)

A.W. Alberts et al.

T.C. Vanaman et al.

J Biol Chem.

(1968)

J.E. Cronan et al.

J Biol Chem.

(1988)

J.G. Olsen et al.

Structure (Camb)

(2001)

X. Qiu et al.

J Biol Chem.

(1999)

C. Davies et al.

Structure Fold Des

(2000)

L. Serre et al.

J Biol Chem.

(1995)

M. Leesong et al.

Structure

(1996)

J.K. Stoops et al.

J Biol Chem.

(1987)

T. Kitamoto et al.

J Mol Biol.

(1988)

S.J. Kolodziej et al.

J Biol Chem.

(1996)

S. Tropf et al.

Chem Biol.

(1998)

A. Stern et al.

J Biol Chem.

(1982)

J-M. Soulié et al.

J Biol Chem.

(1984)

V.S. Rangan et al.

J Biol Chem.

(1991)

V.S. Rangan et al.

J Biol Chem.

(1996)

V.C. Joshi et al.

Arch. Biochem. Biophys.

(1971)

V.S. Rangan et al.

J Biol Chem.

(1997)

A.J. Poulose et al.

Arch. Biochem. Biophys.

(1984)

M. Moche et al.

J Mol Biol.

(2001)

A.K. Joshi et al.

J Biol Chem.

(1993)

P.F. Dodds et al.

J Biol Chem.

(1981)

M. Pazirandeh et al.

J Biol Chem.

(1991)

Y. Tsukamoto et al.

J Biol Chem.

(1983)

J.G. Olsen et al.

FEBS Lett.

(1999)

S. Kumar et al.

J Biol Chem.

(1970)

S. Smith et al.

J Biol Chem.

(1971)

M.A. Kashem et al.

Biochim Biophys Acta

(1988)

Z. Yuan et al.

J Biol Chem.

(1986)

N. Singh et al.

J Biol Chem.

(1984)

S. Kumar et al.

J Biol Chem.

(1972)

J.K. Stoops et al.

J Biol Chem.

(1979)

J.K. Stoops et al.

J Biol Chem.

(1981)

A.K. Joshi et al.

J Biol Chem.

(1998)

V.S. Rangan et al.

J Biol Chem.

(1998)

R.J. Foster et al.

J Biol Chem.

(1985)

H.P. Klein

J Bacteriol.

(1957)

S.J. Wakil

J Am Chem Soc.

(1958)

D.M. Gibson et al.

J Am Chem Soc.

(1958)

S.J. Wakil et al.

Proc Natl Acad Sci USA

(1964)

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ReviewStructural and functional organization of the animal fatty acid synthase

Abstract

Section snippets

Historical perspective

The overall reaction sequence

Substrate loading

Domain map

A revised model for the animal FAS

Perspective

Acknowledgements

Biochim Biophys Acta

J Biol Chem.

Biochim Biophys Acta

J Biol Chem.

J Biol Chem.

Biochem Biophys Res Comm.

Arch. Biochem. Biophys.

J Biol Chem.

Biochem Biophys Res Comm.

Arch. Biochem. Biophys.

J Biol Chem.

J Biol Chem.

Structure (Camb)

J Biol Chem.

Structure Fold Des

J Biol Chem.

Structure

J Biol Chem.

J Mol Biol.

J Biol Chem.

Chem Biol.

J Biol Chem.

J Biol Chem.

J Biol Chem.

J Biol Chem.

Arch. Biochem. Biophys.

J Biol Chem.

Arch. Biochem. Biophys.

J Mol Biol.

J Biol Chem.

J Biol Chem.

J Biol Chem.

J Biol Chem.

FEBS Lett.

J Biol Chem.

J Biol Chem.

Biochim Biophys Acta

J Biol Chem.

J Biol Chem.

J Biol Chem.

J Biol Chem.

J Biol Chem.

J Biol Chem.

J Biol Chem.

J Biol Chem.

J Bacteriol.

J Am Chem Soc.

J Am Chem Soc.

Proc Natl Acad Sci USA

Review
Structural and functional organization of the animal fatty acid synthase