Improving the diffraction quality of heat-shock protein 47 crystals

Area of Science:

• Biochemistry
• Structural Biology
• Drug Discovery

Background:

• Heat-shock protein 47 (HSP47) is crucial for collagen folding and assembly, making it a therapeutic target for fibrotic diseases.
• Previous attempts to crystallize apo dog HSP47 for structure-based drug design were hampered by difficulties in obtaining high-quality crystals and resolving the structure.

Purpose of the Study:

• To develop a robust structure-based drug-design system for HSP47 inhibitors.
• To overcome crystallization challenges previously encountered with apo dog HSP47.

Main Methods:

• Investigated strategies to improve crystal formation and diffraction of HSP47.
• Modified the His-tag location and cleavability (N-terminus).
• Developed and utilized Adnectin crystallization chaperones.

Main Results:

• Initial attempts with C-terminal His-tag resulted in poorly diffracting tetrameric structures with multiple HSP47 molecules per asymmetric unit.
• Moving the His-tag to the N-terminus and making it cleavable improved crystal quality.
• Adnectin chaperones yielded well-diffracting crystals with fewer HSP47 molecules per asymmetric unit, simplifying model building.

Conclusions:

• Successful crystallization of HSP47 was achieved through strategic modifications of purification tags and the use of crystallization chaperones.
• These improved methods facilitate detailed structural analysis of HSP47, paving the way for structure-based inhibitor design.
• The developed crystallization strategies are valuable for advancing therapeutic strategies against fibrotic conditions targeting HSP47.