Very long-chain acyl-CoA synthetases: Human 'bubblegum' represents a new family of proteins capable of activating very long-chain fatty acids

Steven J. Steinberg, Janine Morgenthaler, Ann K. Heinzer, Kirby D. Smith, Paul A Watkins

Research output: Contribution to journalArticle

Abstract

Activation by thioesterification to coenzyme A is a prerequisite for most reactions involving fatty acids. Enzymes catalyzing activation, acyl-CoA synthetases, have been classified by their chain length specificities. The most recently identified family is the very long-chain acyl-CoA synthetases (VLCS). Although several members of this group are capable of activating very long-chain fatty acids (VLCFA), one is a bile acid-CoA synthetase, and others have been characterized as fatty acid transport proteins. It was reported that the Drosophila melanogaster mutant bubblegum (BGM) had elevated VLCFA and that the product of the defective gene had sequence homology to acyl-CoA synthetases. Therefore, we cloned full-length cDNA for a human homolog of BGM, and we investigated the properties of its protein product, hsBG, to determine whether it had VLCS activity. Northern blot analysis showed that hsBG is expressed primarily in brain. Compared with vector-transfected cells, COS-1 cells expressing hsBG had increased acyl-CoA synthetase activity with either long-chain fatty acid (2.4-fold) or VLCFA (2.6-fold) substrates. Despite this increased VLCFA activation, hsBG-expressing cells did not have increased rates of VLCFA degradation. Confocal microscopy showed that hsBG had a cytoplasmic localization in some COS-1 cells expressing the protein, whereas it appeared to associate with plasma membrane in others. Fractionation of these cells revealed that most of the hsBG-dependent acyl-CoA synthetase activity was soluble and not membrane-bound. Immunoaffinity-purified hsBG from transfected COS-1 cells was enzymatically active. hsBG and hsVLCS are only 15% identical, and comparison with sequences of two conserved motifs from all known families of acyl-CoA synthetases revealed that hsBG along with the D. melanogaster and murine homologs comprise a new family of acyl-CoA synthetases. Thus, two protein families are now known that contain enzymes capable of activating VLCFA. Because hsBG is expressed in brain but previously described VLCSs were not highly expressed in this organ, hsBG may play a central role in brain VLCFA metabolism and myelinogenesis.

Original languageEnglish (US)
Pages (from-to)35162-35169
Number of pages8
JournalJournal of Biological Chemistry
Volume275
Issue number45
DOIs
StatePublished - Nov 10 2000

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Coenzyme A Ligases
Fatty Acids
Proteins
COS Cells
Brain
Chemical activation
Drosophila melanogaster
Fatty Acid Transport Proteins
Cells
Cell Fractionation
long-chain-fatty-acid-CoA ligase
Enzyme Activation
Conserved Sequence
Confocal microscopy
Enzymes
Coenzyme A
Cell membranes
Fractionation
Sequence Homology
Chain length

ASJC Scopus subject areas

  • Biochemistry

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Very long-chain acyl-CoA synthetases : Human 'bubblegum' represents a new family of proteins capable of activating very long-chain fatty acids. / Steinberg, Steven J.; Morgenthaler, Janine; Heinzer, Ann K.; Smith, Kirby D.; Watkins, Paul A.

In: Journal of Biological Chemistry, Vol. 275, No. 45, 10.11.2000, p. 35162-35169.

Research output: Contribution to journalArticle

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T2 - Human 'bubblegum' represents a new family of proteins capable of activating very long-chain fatty acids

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