Mitochondrial fatty acid synthesis in Trypanosoma brucei

Jennifer L. Stephens, Hee Lee Soo, Kimberly S. Paul, Paul T. Englund

Research output: Contribution to journalArticle

Abstract

Whereas other organisms utilize type I or type II synthases to make fatty acids, trypanosomatid parasites such as Trypanosoma brucei are unique in their use of a microsomal elongase pathway (ELO) for de novo fatty acid synthesis (FAS). Because of the unusual lipid metabolism of the trypanosome, it was important to study a second FAS pathway predicted by the genome to be a type II synthase. We localized this pathway to the mitochondrion, and RNA interference (RNAi) or genomic deletion of acyl carrier protein (ACP) and β-ketoacyl-ACP synthase indicated that this pathway is likely essential for bloodstream and procyclic life cycle stages of the parasite. In vitro assays show that the largest major fatty acid product of the pathway is C16, whereas the ELO pathway, utilizing ELOs 1, 2, and 3, synthesizes up to C18. To demonstrate mitochondrial FAS in vivo, we radiolabeled fatty acids in cultured procyclic parasites with [14C]pyruvate or [14C]threonine, either of which is catabolized to [14C]acetyl-CoA in the mitochondrion. Although some of the [14C]acetyl-CoA may be utilized by the ELO pathway, a striking reduction in radiolabeled fatty acids following ACP RNAi confirmed that it is also consumed by mitochondrial FAS. ACP depletion by RNAi or gene knockout also reduces lipoic acid levels and drastically decreases protein lipoylation. Thus, octanoate (C8), the precursor for lipoic acid synthesis, must also be a product of mitochondrial FAS. Trypanosomes employ two FAS systems: the unconventional ELO pathway that synthesizes bulk fatty acids and a mitochondrial pathway that synthesizes specialized fatty acids that are likely utilized intramitochondrially.

Original languageEnglish (US)
Pages (from-to)4427-4436
Number of pages10
JournalJournal of Biological Chemistry
Volume282
Issue number7
DOIs
StatePublished - Feb 16 2007

Fingerprint

Trypanosoma brucei brucei
Fatty Acids
Acyl Carrier Protein
RNA Interference
Thioctic Acid
Acetyl Coenzyme A
Parasites
Mitochondria
holo-(acyl-carrier-protein) synthase
Trypanosomiasis
RNA
Genes
Lipoylation
Gene Knockout Techniques
Threonine
Life Cycle Stages
Pyruvic Acid
Lipid Metabolism
Life cycle
Assays

ASJC Scopus subject areas

  • Biochemistry

Cite this

Stephens, J. L., Soo, H. L., Paul, K. S., & Englund, P. T. (2007). Mitochondrial fatty acid synthesis in Trypanosoma brucei. Journal of Biological Chemistry, 282(7), 4427-4436. https://doi.org/10.1074/jbc.M609037200

Mitochondrial fatty acid synthesis in Trypanosoma brucei. / Stephens, Jennifer L.; Soo, Hee Lee; Paul, Kimberly S.; Englund, Paul T.

In: Journal of Biological Chemistry, Vol. 282, No. 7, 16.02.2007, p. 4427-4436.

Research output: Contribution to journalArticle

Stephens, JL, Soo, HL, Paul, KS & Englund, PT 2007, 'Mitochondrial fatty acid synthesis in Trypanosoma brucei', Journal of Biological Chemistry, vol. 282, no. 7, pp. 4427-4436. https://doi.org/10.1074/jbc.M609037200
Stephens, Jennifer L. ; Soo, Hee Lee ; Paul, Kimberly S. ; Englund, Paul T. / Mitochondrial fatty acid synthesis in Trypanosoma brucei. In: Journal of Biological Chemistry. 2007 ; Vol. 282, No. 7. pp. 4427-4436.
@article{06943545ac6243beacd3b704402b0e30,
title = "Mitochondrial fatty acid synthesis in Trypanosoma brucei",
abstract = "Whereas other organisms utilize type I or type II synthases to make fatty acids, trypanosomatid parasites such as Trypanosoma brucei are unique in their use of a microsomal elongase pathway (ELO) for de novo fatty acid synthesis (FAS). Because of the unusual lipid metabolism of the trypanosome, it was important to study a second FAS pathway predicted by the genome to be a type II synthase. We localized this pathway to the mitochondrion, and RNA interference (RNAi) or genomic deletion of acyl carrier protein (ACP) and β-ketoacyl-ACP synthase indicated that this pathway is likely essential for bloodstream and procyclic life cycle stages of the parasite. In vitro assays show that the largest major fatty acid product of the pathway is C16, whereas the ELO pathway, utilizing ELOs 1, 2, and 3, synthesizes up to C18. To demonstrate mitochondrial FAS in vivo, we radiolabeled fatty acids in cultured procyclic parasites with [14C]pyruvate or [14C]threonine, either of which is catabolized to [14C]acetyl-CoA in the mitochondrion. Although some of the [14C]acetyl-CoA may be utilized by the ELO pathway, a striking reduction in radiolabeled fatty acids following ACP RNAi confirmed that it is also consumed by mitochondrial FAS. ACP depletion by RNAi or gene knockout also reduces lipoic acid levels and drastically decreases protein lipoylation. Thus, octanoate (C8), the precursor for lipoic acid synthesis, must also be a product of mitochondrial FAS. Trypanosomes employ two FAS systems: the unconventional ELO pathway that synthesizes bulk fatty acids and a mitochondrial pathway that synthesizes specialized fatty acids that are likely utilized intramitochondrially.",
author = "Stephens, {Jennifer L.} and Soo, {Hee Lee} and Paul, {Kimberly S.} and Englund, {Paul T.}",
year = "2007",
month = "2",
day = "16",
doi = "10.1074/jbc.M609037200",
language = "English (US)",
volume = "282",
pages = "4427--4436",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "7",

}

TY - JOUR

T1 - Mitochondrial fatty acid synthesis in Trypanosoma brucei

AU - Stephens, Jennifer L.

AU - Soo, Hee Lee

AU - Paul, Kimberly S.

AU - Englund, Paul T.

PY - 2007/2/16

Y1 - 2007/2/16

N2 - Whereas other organisms utilize type I or type II synthases to make fatty acids, trypanosomatid parasites such as Trypanosoma brucei are unique in their use of a microsomal elongase pathway (ELO) for de novo fatty acid synthesis (FAS). Because of the unusual lipid metabolism of the trypanosome, it was important to study a second FAS pathway predicted by the genome to be a type II synthase. We localized this pathway to the mitochondrion, and RNA interference (RNAi) or genomic deletion of acyl carrier protein (ACP) and β-ketoacyl-ACP synthase indicated that this pathway is likely essential for bloodstream and procyclic life cycle stages of the parasite. In vitro assays show that the largest major fatty acid product of the pathway is C16, whereas the ELO pathway, utilizing ELOs 1, 2, and 3, synthesizes up to C18. To demonstrate mitochondrial FAS in vivo, we radiolabeled fatty acids in cultured procyclic parasites with [14C]pyruvate or [14C]threonine, either of which is catabolized to [14C]acetyl-CoA in the mitochondrion. Although some of the [14C]acetyl-CoA may be utilized by the ELO pathway, a striking reduction in radiolabeled fatty acids following ACP RNAi confirmed that it is also consumed by mitochondrial FAS. ACP depletion by RNAi or gene knockout also reduces lipoic acid levels and drastically decreases protein lipoylation. Thus, octanoate (C8), the precursor for lipoic acid synthesis, must also be a product of mitochondrial FAS. Trypanosomes employ two FAS systems: the unconventional ELO pathway that synthesizes bulk fatty acids and a mitochondrial pathway that synthesizes specialized fatty acids that are likely utilized intramitochondrially.

AB - Whereas other organisms utilize type I or type II synthases to make fatty acids, trypanosomatid parasites such as Trypanosoma brucei are unique in their use of a microsomal elongase pathway (ELO) for de novo fatty acid synthesis (FAS). Because of the unusual lipid metabolism of the trypanosome, it was important to study a second FAS pathway predicted by the genome to be a type II synthase. We localized this pathway to the mitochondrion, and RNA interference (RNAi) or genomic deletion of acyl carrier protein (ACP) and β-ketoacyl-ACP synthase indicated that this pathway is likely essential for bloodstream and procyclic life cycle stages of the parasite. In vitro assays show that the largest major fatty acid product of the pathway is C16, whereas the ELO pathway, utilizing ELOs 1, 2, and 3, synthesizes up to C18. To demonstrate mitochondrial FAS in vivo, we radiolabeled fatty acids in cultured procyclic parasites with [14C]pyruvate or [14C]threonine, either of which is catabolized to [14C]acetyl-CoA in the mitochondrion. Although some of the [14C]acetyl-CoA may be utilized by the ELO pathway, a striking reduction in radiolabeled fatty acids following ACP RNAi confirmed that it is also consumed by mitochondrial FAS. ACP depletion by RNAi or gene knockout also reduces lipoic acid levels and drastically decreases protein lipoylation. Thus, octanoate (C8), the precursor for lipoic acid synthesis, must also be a product of mitochondrial FAS. Trypanosomes employ two FAS systems: the unconventional ELO pathway that synthesizes bulk fatty acids and a mitochondrial pathway that synthesizes specialized fatty acids that are likely utilized intramitochondrially.

UR - http://www.scopus.com/inward/record.url?scp=33947414585&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33947414585&partnerID=8YFLogxK

U2 - 10.1074/jbc.M609037200

DO - 10.1074/jbc.M609037200

M3 - Article

C2 - 17166831

AN - SCOPUS:33947414585

VL - 282

SP - 4427

EP - 4436

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 7

ER -