Molecular cloning of chicken aggrecan. Structural analyses

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Aggrecan is a large proteoglycan crucial for cartilage structure and function.
• Previous studies utilized aggrecan as a model proteoglycan, defining its structure and domain organization through molecular cloning.

Purpose of the Study:

• To determine the complete coding sequence of chicken sternal cartilage aggrecan.
• To compare the primary structure of chicken aggrecan with aggrecans from other species (rat, human, bovine).
• To identify conserved and unique features in chicken aggrecan's domain structure.

Main Methods:

• cDNA and genomic DNA sequencing were employed to obtain the full coding sequence of chicken aggrecan.
• Bioinformatic analysis was used to compare the deduced amino acid sequence with homologous sequences from other species.
• Genomic DNA sequencing was utilized to compare exon structures.

Main Results:

• The complete coding sequence of chicken aggrecan is 6117 bp, encoding 1951 amino acids.
• Highly conserved domains (70-80% identity) include the N-terminal G1 and G2, and the C-terminal G3 domains.
• Chicken aggrecan exhibits unique features in its chondroitin sulphate (CS) and keratan sulphate (KS) domains, with a smaller CS domain and distinct repeat sequences, and a non-repetitive KS domain.

Conclusions:

• Chicken aggrecan shares conserved domain structures with other species but possesses unique CS and KS domains.
• These variations suggest that different CS and KS domain variants may have evolved independently to serve specific biochemical and physiological roles.
• The study highlights the structural diversity of aggrecan across species, contributing to our understanding of proteoglycan evolution and function.