Enhanced Production of Dopa-Incorporated Mussel Adhesive Protein Using
Engineered Translational Machineries
Abstract
Mussel adhesive proteins (MAPs) have great potential as bioglues, in
particular in wet conditions. Although in vivo residue-specific
incorporation of 3,4-dihydroxyphenylalanine (Dopa) in
tyrosine-auxotrophic Escherichia coli cells allows production of
bioengineered MAPs (bMAPs), the low production yield hinders the
practical application of bMAPs. Such low production yield of
Dopa-incorporated bMAPs (Dopa-bMAPs) was known to be caused by low
translational activity of a noncanonical amino acid, Dopa, in E. coli
cells. Herein, in order to enhance the production yield of Dopa-bMAPs,
we investigated the coexpression of Dopa-recognizing tyrosyl-tRNA
synthetases (TyrRSs). In order to use the Dopa-specific Methanococcus
jannascii TyrRS (MjTyrRS-Dopa), we altered the anti-codon of
tyrosyl-tRNA amber suppressor into AUA (MjtRNATyrAUA) to recgonize a
tyrosine codon (MjtRNATyrAUA). Co-overexpression of MjTyrRS-Dopa and
MjtRNATyrAUA increased the production yield of Dopa-MAP by 57%.
Similarly, overexpression of E. coli TyrRS (EcTyrRS) led to a 72%
higher production yield of Dopa-incorporated bMAP. Even with
coexpression of Dopa-recognizing TyrRSs, Dopa-bMAPs have a high Dopa
incorporation yield (over 90%) compared to Dopa-bMAPs prepared without
any coexpression of TyrRS.