5-hydroxytryptophan biosynthesis

 

I was intrigued by a recent article in the journal Chem (link)  entitled "Creation of Bacterial Cells with 5-hydroxytryptophan as a 21st Amino Acid Building Block" by Chen et al. in the group of Han Xiao at Rice University, wherein they make a strain that metabolically produces 5-hydroxytryptophan for genetic code expansion. It is an interesting example of why metabolic engineering is non-trivial and how scientific research does not progress in a logical fashion.

Stay hydrated

Waters can be an integral part of a protein structure, in fact, it is common to find water crystallised tightly in an X-ray structure. Including these waters can change the Rosetta score and may improve agreement with experiment. The score is in Rosetta energy units (REU), rather than a direct measurement of Gibbs free energy. Explicit waters can be added in Rosetta/Pyrosetta thanks to the SPaDES algorithm described in Lai et al. 2017. Here is a guide to using it in Pyrosetta.