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Title: The Crystal Structure of an Integral Membrane Fatty Acid α-Hydroxylase

Journal Article · · Journal of Biological Chemistry
 [1];  [1];  [2];  [2];  [3]
  1. Hauptman-Woodward Medical Research Inst., Buffalo, NY (United States)
  2. Univ. of Rochester School of Medicine and Dentistry, Rochester, NY (United States)
  3. Hauptman-Woodward Medical Research Inst., Buffalo, NY (United States); State Univ. of New York, Buffalo, NY (United States)
+ Show Author Affiliations

Neuronal electrical impulse propagation is facilitated by the myelin sheath, a compact membrane surrounding the axon. The myelin sheath is highly enriched in galactosylceramide (GalCer) and its sulfated derivative sulfatide. Over 50% of GalCer and sulfatide in myelin is hydroxylated by the integral membrane enzyme fatty acid 2-hydroxylase (FA2H). GalCer hydroxylation contributes to the compact nature of the myelin membrane, and mutations in FA2H result in debilitating leukodystrophies and spastic paraparesis. We report here the 2.6 Å crystal structure of sphingolipid α-hydroxylase (Scs7p), a yeast homolog of FA2H. The Scs7p core is composed of a helical catalytic cap domain that sits atop four transmembrane helices that anchor the enzyme in the endoplasmic reticulum. The structure contains two zinc atoms coordinated by the side chains of 10 highly conserved histidines within a dimetal center located near the plane of the cytosolic membrane. We used a yeast genetic approach to confirm the important role of the dimetal-binding histidines in catalysis and identified Tyr-322 and Asp-323 as critical determinants involved in the hydroxylase reaction. Examination of the Scs7p structure, coupled with molecular dynamics simulations, allowed for the generation of a model of ceramide binding to Scs7p. Comparison of the Scs7p structure and substrate-binding model to the structure of steroyl-CoA desaturase revealed significant differences in the architecture of the catalytic cap domain and location of the dimetal centers with respect to the membrane. These observations provide insight into the different mechanisms of substrate binding and recognition of substrates by the hydroxylase and desaturase enzymes.

Research Organization:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC); National Inst. of Health
Grant/Contract Number:
U54GM094611
OSTI ID:
1236868
Journal Information:
Journal of Biological Chemistry, Vol. 290, Issue 50; ISSN 0021-9258
Publisher:
American Society for Biochemistry and Molecular BiologyCopyright Statement
Country of Publication:
United States
Language:
ENGLISH
Citation Metrics:
Cited by: 34 works
Citation information provided by
Web of Science

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Cited By (5)

Sphingolipids and their metabolism in physiology and disease journal November 2017
An efficient, step-economical strategy for the design of functional metalloproteins journal February 2019
Sphingomyelins and ceramides with VLCPUFAs are excluded from low-density raft-like domains in differentiating spermatogenic cells journal January 2017
Neural symptoms in a gene knockout mouse model of Sjögren‐Larsson syndrome are associated with a decrease in 2‐hydroxygalactosylceramide journal August 2018
Identification of a crucial amino acid implicated in the hydroxylation/desaturation ratio of CpFAH12 bifunctional hydroxylase journal July 2019

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Related Subjects

59 BASIC BIOLOGICAL SCIENCES
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ceramide
crystal structure
endoplasmic reticulum (ER)
membrane enzyme
metalloenzyme
myelin
sphingolipid
structural biology