3T3T

1.38 A structure of human frataxin variant Q148G

Summary for 3T3T

• Entry DOI: 10.2210/pdb3t3t/pdb
• Related: 3T3J 3T3K 3T3L 3T3X
• Descriptor: Frataxin, mitochondrial, SULFATE ION (3 entities in total)
• Functional Keywords: fe-s cluster biosynthesis, human mitochondria, oxidoreductase
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: Q16595
• Total number of polymer chains: 4
• Total formula weight: 56882.53

Authors

Bridwell-Rabb, J.,Winn, A.M.,Barondeau, D.P. (deposition date: 2011-07-25, release date: 2011-08-10, Last modification date: 2024-02-28)

Primary citation

Bridwell-Rabb, J.,Winn, A.M.,Barondeau, D.P.
Structure-Function Analysis of Friedreich's Ataxia Mutants Reveals Determinants of Frataxin Binding and Activation of the Fe-S Assembly Complex.
Biochemistry, 50:7265-7274, 2011

PubMed Abstract: Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease associated with the loss of function of the protein frataxin (FXN) that results from low FXN levels due to a GAA triplet repeat expansion or, occasionally, from missense mutations in the FXN gene. Here biochemical and structural properties of FXN variants, including three FRDA missense mutations (N146K, Q148R, and R165C) and three related mutants (N146A, Q148G, and Q153A), were determined in an effort to understand the structural basis for the loss of function. In vitro assays revealed that although the three FRDA missense mutations exhibited similar losses of cysteine desulfurase and Fe-S cluster assembly activities, the causes for these activation defects were distinct. The R165C variant exhibited a k(cat)/K(M) higher than that of native FXN but weak binding to the NFS1, ISD11, and ISCU2 (SDU) complex, whereas the Q148R variant exhibited the lowest k(cat)/K(M) of the six tested FXN variants and only a modest binding deficiency. The order of the FXN binding affinities for the SDU Fe-S assembly complex was as follows: FXN > Q148R > N146A > Q148G > N146K > Q153A > R165C. Four different classes of FXN variants were identified on the basis of their biochemical properties. Together, these structure-function studies reveal determinants for the binding and allosteric activation of the Fe-S assembly complex and provide insight into how FRDA missense mutations are functionally compromised.

PubMed: 21776984
DOI: 10.1021/bi200895k

Experimental method

X-RAY DIFFRACTION (1.38 Å)