The Crystal Structure of a Collagen-like Polypeptide with 3(S)-Hydroxyproline Residues in the Xaa Position Forms a Standard 7/2 Collagen Triple Helix

Background: Charged residues, abundant in collagen, participate in stabilizing and packing interactions. Results: Two contact geometries, axial and lateral, are observed in charge pair hydrogen bonding. Conclusion: Axial salt bridges provide greater stabilization to the triple helical fold than lateral ones. Significance: Understanding interstrand amino acid interactions in collagen will improve interpretation of natural collagen and will allow more effective design of collagen mimics.

Section: Resultsmentioning

confidence: 78%

Structural Insights into Charge Pair Interactions in Triple Helical Collagen-like Proteins

Fallas

Dong

Tao

et al. 2012

“…This implies biological benefits through a fundamental contribution to the properties of collagen structure itself. We recently suggested, based on the observed D-periodic spacing (7) and externally directed 3(S)OH (24), that inter-triple-helical hydrogen bonding may be involved, for example in helping fine-tune the polymeric assembly of fibrils and basement membrane networks. With this concept in mind, the possible consequences of a 3Hyp repeat at the junction of the triple-helix and the C-terminal telopeptide/propeptide are worth considering.…”

Section: Discussionmentioning

confidence: 99%

A Novel 3-Hydroxyproline (3Hyp)-rich Motif Marks the Triple-helical C Terminus of Tendon Type I Collagen

Eyre

Weis

Hudson

et al. 2011

Because of its unique physical and chemical properties, rat tail tendon collagen has long been favored for crystallographic and biochemical studies of fibril structure. In studies of the distribution of 3-hydroxyproline in type I collagen of rat bone, skin, and tail tendon by mass spectrometry, the repeating sequences of Gly-Pro-Pro (GPP) triplets at the C terminus of ␣1(I) and ␣2(I) chains were shown to be heavily 3-hydroxylated in tendon but not in skin and bone. By isolating the tryptic peptides and subjecting them to Edman sequence analysis, the presence of repeating 3-hydroxyprolines in consecutive GPP triplets adjacent to 4-hydroxyproline was confirmed as a unique feature of the tendon collagen. A 1960s study by Piez et al. (Piez, K. A., Eigner, E. A., and Lewis, M. S. (1963) Biochemistry 2, 58 -66) in which they compared the amino acid compositions of rat skin and tail tendon type I collagen chains indeed showed 3-4 residues of 3Hyp in tendon ␣1(I) and ␣2(I) chains but only one 3Hyp residue in skin ␣1(I) and none in ␣2(I). The present work therefore confirms this difference and localizes the additional 3Hyp to the GPP repeat at the C terminus of the triple-helix. We speculate on the significance in terms of a potential function in contributing to the unique assembly mechanism and molecular packing in tendon collagen fibrils and on mechanisms that could regulate 3-hydroxylation at this novel substrate site in a tissuespecific manner.Prolyl 3-hydroxylation, a long recognized quantitatively minor post-translational modification of collagen (1), has received much attention in the last few years after gene mutations affecting its formation were found to cause recessive forms of osteogenesis imperfecta (2-5). A single primary site of 3-hydroxyproline (3Hyp) 2 is present in normal collagen ␣1(I) and ␣1(II) chains at Pro-986 of the triple-helix (6, 7) but is not hydroxylated in the tissues of mice and humans with recessive osteogenesis imperfecta caused by mutations in CRTAP or LEPRE1 (the gene encoding P3H1) (2-5). The LEPRE1 gene encodes P3H1, which is one of three prolyl 3-hydroxylases (P3H1, P3H2, and P3H3) in the mammalian genome. CRTAP encodes a protein that is homologous to the N-terminal half of P3H1, which it associates with P3H1 together with cyclophilin B to form the functional enzyme complex required for Pro-986 3-hydroxylation of unfolded collagen chains in the endoplasmic reticulum (8).We recently identified several other sites of prolyl 3-hydroxylation in fibrillar collagen chains including Pro-707 in ␣2(I) and ␣2(V), Pro-944 in ␣1(II) and ␣2(V), Pro-470 in ␣2(V), and Pro-434, Pro-665, and Pro-692 in ␣1(V), ␣1(XI), and ␣2(XI) but a lack of any 3-hydroxyproline in the mammalian ␣1(III) chain (7). The D-periodic spacing between three of these additional sites in clade A collagen chains (␣1(I), ␣2(I), ␣1(II), and ␣2(V)) and between two in clade B (␣1(V), ␣1(XI), and ␣2(XI)) suggested a role in fibril formation. In pursuing this concept further, we investigated the potential for differences in 3-hydrox...

“…It is not surprising that with the improved sensitivity and specificity afforded by our MS-driven proteomics workflow that we have identified numerous PTMs previously undiscovered, including those present at relatively low stoichiometric abundances. Interestingly, 3-Hyp residues point away from the triple helix (81), implying roles in protein-protein interactions as the bases of biological function for these residues. The presence of numbers of sites that can be differentially modified by P3Hs in a given tissue suggests a previously unknown mechanism for dynamic modification of the functions and intermolecular interactions of ␣1(V) chains and col(V) and perhaps other collagen types as well.…”

Section: Comparison Of the Col1 Ptms Of Bovine Placental ␣1(v) And Humentioning

confidence: 99%

Comprehensive Mass Spectrometric Mapping of the Hydroxylated Amino Acid residues of the α1(V) Collagen Chain

Yang

Park

Davis

et al. 2012

Background: ␣1(V) is an extensively modified collagen chain important in disease. Results: Comprehensive mapping of ␣1(V) post-translational modifications reveals unexpectedly large numbers of X-position hydroxyprolines in Gly-X-Y amino acid triplets. Conclusion:The unexpected abundance of X-position hydroxyprolines suggests a mechanism for differential modification of collagen properties. Significance: Positions, numbers, and occupancy of modified sites can provide insights into ␣1(V) biological properties.