Biologically and diagenetically derived peptide modifications in moa collagens

Area of Science:

• Paleoproteomics
• Molecular Paleontology
• Biochemistry

Background:

• Protein modifications over time in natural environments are poorly understood.
• Characterizing these modifications is crucial for interpreting ancient DNA and protein sequences from fossils.
• The extinct moa (Dinornithidae) offers a unique model for studying protein preservation and degradation.

Purpose of the Study:

• To investigate protein preservation, post-translational modifications (PTMs), and diagenetic alterations in moa.
• To identify and characterize both in vivo and diagenetic modifications in moa collagen.
• To establish a baseline for evaluating proteomic studies of other fossil specimens.

Main Methods:

• Analysis of moa protein extracts using mass spectrometry.
• Identification of peptides from collagen I, II, and V.
• Characterization of amino acid modifications through peptide sequencing.

Main Results:

• Identification of biologically derived PTMs (methylation, alkylation, hydroxylation, fucosylation) consistent with extant proteins.
• Detection of novel, likely diagenetic modifications including loss of hydroxylation, carboxymethyllysine, peptide backbone cleavage, and deamidation.
• Sequencing of moa collagen provided insights into its molecular structure and modifications.

Conclusions:

• Moa collagen exhibits both expected biological modifications and novel diagenetic alterations.
• These findings establish a crucial baseline for interpreting proteomic data from fossilized proteins.
• The study provides a framework for understanding the molecular relationships of moa to other species.