Structural analysis reveals pathomechanisms associated with pseudoxanthoma elasticum-causing mutations in the ABCC6...

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• Mutations in the ABC subfamily C member 6 (ABCC6) transporter are linked to pseudoxanthoma elasticum (PXE).
• PXE is characterized by ectopic mineralization affecting multiple tissues.
• The functional impact of most identified ABCC6 mutations remains mechanistically unclear.

Purpose of the Study:

• To investigate how PXE-associated mutations affect ABCC6 transporter biosynthesis and structure.
• To elucidate the role of the N-terminal nucleotide-binding domain (NBD1) in ABCC6 function and PXE pathogenesis.

Main Methods:

• High-resolution X-ray crystallography to determine the structure of human ABCC6 NBD1 at 2.3 Å.
• Biophysical and biochemical analyses of PXE-associated mutations within NBD1.
• Assessment of full-length ABCC6 protein processing and expression in relation to NBD1 alterations.

Main Results:

• A high-resolution X-ray structure of ABCC6 NBD1 was obtained, serving as a structural template.
• Biochemical analyses demonstrated that multiple PXE-causing mutations alter the structural properties of NBD1.
• A strong correlation was observed between altered NBD properties and impaired processing/expression of full-length ABCC6.

Conclusions:

• A significant proportion of PXE-associated mutations in ABCC6 NBD1 directly impact its structural integrity.
• These structural changes in NBD1 lead to defects in the maturation of the full-length ABCC6 protein.
• Understanding these mutation-induced alterations provides crucial insights into the molecular basis of PXE.