Comprehensive mass spectrometric mapping of the hydroxylated amino acid residues of the ?1(V) collagen chain.

ABSTRACT: ?1(V) is an extensively modified collagen chain important in disease.Comprehensive mapping of ?1(V) post-translational modifications reveals unexpectedly large numbers of X-position hydroxyprolines in Gly-X-Y amino acid triplets.The unexpected abundance of X-position hydroxyprolines suggests a mechanism for differential modification of collagen properties.Positions, numbers, and occupancy of modified sites can provide insights into ?1(V) biological properties. Aberrant expression of the type V collagen ?1(V) chain can underlie the connective tissue disorder classic Ehlers-Danlos syndrome, and autoimmune responses against the ?1(V) chain are linked to lung transplant rejection and atherosclerosis. The ?1(V) collagenous COL1 domain is thought to contain greater numbers of post-translational modifications (PTMs) than do similar domains of other fibrillar collagen chains, PTMs consisting of hydroxylated prolines and lysines, the latter of which can be glycosylated. These types of PTMs can contribute to epitopes that underlie immune responses against collagens, and the high level of PTMs may contribute to the unique biological properties of the ?1(V) chain. Here we use high resolution mass spectrometry to map such PTMs in bovine placental ?1(V) and human recombinant pro-?1(V) procollagen chains. Findings include the locations of those PTMs that vary and those PTMs that are invariant between these ?1(V) chains from widely divergent sources. Notably, an unexpectedly large number of hydroxyproline residues were mapped to the X-positions of Gly-X-Y triplets, contrary to expectations based on previous amino acid analyses of hydrolyzed ?1(V) chains from various tissues. We attribute this difference to the ability of tandem mass spectrometry coupled to nanoflow chromatographic separations to detect lower-level PTM combinations with superior sensitivity and specificity. The data are consistent with the presence of a relatively large number of 3-hydroxyproline sites with less than 100% occupancy, suggesting a previously unknown mechanism for the differential modification of ?1(V) chain and type V collagen properties.

SUBMITTER: Yang C 

PROVIDER: S-EPMC3504773 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature