title: Expression, purification and characterization of fourth FAS1 domain of TGFβIp-associated corneal dystrophic mutants.
abstract: Corneal dystrophies (CDs) are a group of inherited bilateral disorders affecting the corneal tissue of the eye. Most of these CDs in the stromal layer of the cornea have been associated with mutations found on the TGFBI gene that codes for a 683-amino acid transforming growth factor induced protein (TGFβIp). These mutations have been found to induce atypical aggregation and progressive accumulation of protein aggregates in the cornea that leads to loss of corneal transparency and hence blindness. At present, 65 distinct pathogenic mutations have been identified in TGFBI that are associated with different clinical phenotypes. More than 80% of these missense mutations occur in the 4th FAS (fasciclin-like) 1 domain. Current treatment includes surgical intervention, which often involves high recurrence rates. Hence, it is imperative to examine the properties of the TGFβIp and the pathogenic mutant proteins to understand the pathology of the disease mechanism and to develop potent therapeutics. Here, we report the recombinant expression, purification, characterization and the effect of four clinically significant pathogenic TGFβIp mutants - R555W, H572R, A620D, and H626R on the biophysical properties of the wild type (WT) 4th FAS1 domain of TGFβIp. While a higher proportion of the R555W, H572R and H626R mutants of the 4th FAS1 domains remained stable, the A620D mutant largely existed as inclusion bodies in native state and aggregates under physiological conditions. These mutants present a unique platform to examine protein aggregation-prone diseases wherein single amino-acid mutations present distinct pathogenic phenotypes. Though pathogenically and phenotypically diverse, these mutants do not exhibit variations in secondary structure and stability, except for the A620D mutant, when examined by CD and UV spectroscopy.
authors.affiliation: Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore.
authors.forename: Murugan
authors.initials: M
authors.lastname: Elavazhagan
authors.forename: Rajamani
authors.initials: R
authors.lastname: Lakshminarayanan
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Lim Wei
authors.initials: LW
authors.lastname: Ting
authors.forename: Louis
authors.initials: L
authors.lastname: Tong
authors.forename: Roger W
authors.initials: RW
authors.lastname: Beuerman
authors.forename: Shyam S
authors.initials: SS
authors.lastname: Chaurasia
authors.forename: Jodhbir S
authors.initials: JS
authors.lastname: Mehta
mesh_terms: D000595:Amino Acid Sequence; D002853:Chromatography, Liquid; D002942:Circular Dichroism; D003001:Cloning, Molecular; D003198:Computer Simulation; D003317:Corneal Dystrophies, Hereditary / Q000235:genetics*; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D020125:Mutation, Missense; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D013050:Spectrometry, Fluorescence; D053719:Tandem Mass Spectrometry; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D000099222:betaIG-H3 Protein
chemical_list: D016326:Extracellular Matrix Proteins; D046912:Multiprotein Complexes; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D000099222:betaIG-H3 Protein