Sequences with glycine in every third position have been detected in DNA derived sequences of proteins in phages and bacteria and it was suggested that these regions trimerise to collagenous structures. Related sequences are found in proteins of mollusks and slime mold. The sequences contain a much lower fraction of proline than mammalian collagens and it is unknown how many of the prolines, if any, are converted to hydroxyproline. Therefore, for triple helix formation other stabilizing interactions than those known for mammalian collagens are required. Strikingly, aspartate and asparagine are abundant in collagen-like sequences of phage tail fibre proteins and of related sequences in nacrein of oyster pearls suggesting a possible stabilization by calcium binding.
Volume 134, 2022
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