Crystal structure of the obese protein Ieptin-E100

Abstract

Mutations in the obese gene (OB) or in the gene encoding the OB receptor(OB-R) result in obesity, infertility and diabetes in a variety of mouse phenotypes. The demonstration that OB protein (also known as leptin) can normalize body weight in ob/ob mice has generated enormous interest. Most human obesity does not appear to result from a mutant form of leptin: rather, serum leptin concentrations are increased and there is an apparent inability to transport it to the central nervous system (CNS). Injection of leptin into the CNS of overfed rodents resistant to peripheral administration was found to induce biological activity. Consequently, for the leptin to act as a weight-lowering hormone in human obesity, it appears that appropriate concentrations must be present in the CNS. This places a premium on understanding the structure of the hormone in order to design more potent and selective agonists. Here we report the crystal structure at 2.4A resolution of a human mutant OB protein (leptin-E100) that has comparable biological activity to wild type but which crystallizes more readily. The structure reveals a four-helix bundle similar to that of the long-chain helical cytokine family.

Leptin: its role in obesity and beyond

“…Thus, studies are underway to establish the safety and efficacy of leptin administration to obese human subjects. Moreover, both the elucidation of the crystal structure of a human mutant leptin protein and the localization of leptin activity to the amino acid residues 106±140 raise hopes for the development of smaller, more potent peptide analogues of leptin that may have therapeutic potential or can be used to clarify leptin physiology in vivo [114,115].…”

Amino Acid Contribution to Protein Solubility: Asp, Glu, and Ser Contribute more Favorably than the other Hydrophilic Amino Acids in RNase Sa

“…For example, human leptin is a protein therapeutic that is susceptible to aggregation -especially at high dosages in physiological conditions 11 . The crystal structure of this protein was determined only after introduction of a mutation (W100E) that increased the solubility of the protein 33 . The solubility of human leptin was successfully increased for its formulation as a protein therapeutic through several hydrophobic to hydrophilic mutations 11 .…”

Design and application of a polyclonal peptide antiserum for the universal detection of leptin protein

“…After intracellular processing of the 167 amino acid pro-hormone to cleave a 21 amino acid signal peptide segment, the mature form of leptin is secreted into the bloodstream where it circulates as a 146 amino acid (16 kDa) protein [1]. Crystal structure and NMR studies have characterized leptin as a four-helix bundle cytokine containing a single disulfide bond (Cys -Cys ) that is essential, both to its structure and to its function 96 146 [2,3]. In mammals, leptin is expressed primarily in white adipose tissue, although other tissues such as gastric epithelial lining, placenta, muscle, brain, pituitary, and hypothalamus have also been found to be sites of leptin expression [1].…”

“…Our results, reported here, detail the use of this polyclonal peptide . Amino acid sequences were derived from gene coding sequence data deposited in GenBank or from a previous report [2]. Shaded boxes indicate contiguous, totally conserved regions of amino acid sequence within the protein.…”