Several yeast systems have recently been developed for the recombinant production of gelatin and collagen. Amino acid sequence-specific prolyl 4-hydroxylation is essential for the gel-forming capacity of gelatin and for the proper folding of (pro)collagen. This post-translational modification is generally considered to be absent in microbial eukaryotic systems and therefore co-expression of heterologous (human or animal) prolyl 4-hydroxylase would be required. However, we found that the well-known protein expression host Hansenula polymorpha unexpectedly does have the endogenous capacity for prolyl 4-hydroxylation. Without co-expression of a heterologous prolyl 4-hydroxylase, both an endogenous collagen-like protein and a heterologously expressed collagen fragment were found to be sequence-specifically hydroxylated.
de Bruin, E. C., Werten, M. W. T., Laane, C., & de Wolf, F. A. (2002). Endogenous prolyl 4-hydroxylation in Hansenula polymorpha and its use for the production of hydroxylated recombinant gelatin. FEMS Yeast Research, 1(4), 291-298. https://doi.org/10.1016/S1567-1356(01)00042-3