Hepatocyte nuclear factor 4 is a transcription factor that constitutively binds fatty acids.
The 2.7 A X-ray crystal structure of the HNF4gamma ligand binding domain (LBD) revealed the presence of a fatty acid within the pocket, with the AF2 helix in a conformation characteristic of a transcriptionally active nuclear receptor. GC/MS and NMR analysis of chloroform/methanol extracts from purified HNF4alpha and HNF4gamma LBDs identified mixtures of saturated and cis-monounsaturated C14-18 fatty acids. The purified HNF4 LBDs interacted with nuclear receptor coactivators, and both HNF4 subtypes show high constitutive activity in transient transfection assays, which was reduced by mutations designed to interfere with fatty acid binding. The endogenous fatty acids did not readily exchange with radiolabeled palmitic acid, and all attempts to displace them without denaturing the protein failed. Our results suggest that the HNF4s may be transcription factors that are constitutively bound to fatty acids.
Wisely
G Bruce
GB
GlaxoSmithKline Inc., 5 Moore Drive, Research Triangle Park, NC 27709, USA.
Miller
Ann B
AB
Davis
Roderick G
RG
Thornquest
Alan D
AD
Johnson
Robert
R
Spitzer
Tim
T
Sefler
Andrea
A
Shearer
Barry
B
Moore
John T
JT
Miller
Aaron B
AB
Willson
Timothy M
TM
Williams
Shawn P
SP
D000595:Amino Acid Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D002460:Cell Line; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D051557:Hepatocyte Nuclear Factor 4; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D020033:Protein Isoforms / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism*; D014158:Transcription, Genetic
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D005227:Fatty Acids; C496592:HNF4A protein, human; C496597:HNF4G protein, human; D051557:Hepatocyte Nuclear Factor 4; C403128:MLX protein, human; D010750:Phosphoproteins; D020033:Protein Isoforms; D014157:Transcription Factors