Lactococcus lactis as expression host for the biosynthetic incorporation of tryptophan analogues in recombinant proteins

Mohamed El Khattabi , Maarten L. Van Roosmalen , Dennis Jager , Heidi Metselaar , Hjalmar Permentier , Kees Leenhouts (1) , Jaap Broos

1 Biomade Technology

Incorporation of tryptophan (Trp) analogues into a protein may facilitate its structural analysis by spectroscopic techniques. Development of a biological system for the biosynthetic incorporation of such analogues into proteins is of considerable importance. The Gram-negative Escherichia coli is the only prokaryotic expression host regularly used for the incorporation of Trp analogues into recombinant proteins. Here we present the use of the versatile Gram-positive expression host Lactococcus lactis for the incorporation of Trp analogues. The availability of a tightly regulated expression system for this organism, the possibility to secrete modified proteins into the growth medium and the construction of the trp-synthetase deletion strain PA1002 of L. lactis rendered this organism potentially an efficient tool for the incorporation of Trp analogues in recombinant proteins. The Trp analogues 7-azatryptophan, 5-fluorotryptophan and 5-hydroxytryptophan were incorporated with efficiencies of >97%, >97% and 89%, respectively. Interestingly, 5-methyltryptophan could be incorporated with 92% efficiency. Successful biosynthetical incorporation of 5-methylTrp in recombinant proteins has not been reported before.

Mots clés: Life Sciences

Mohamed El Khattabi, Maarten L. Van Roosmalen, Dennis Jager, Heidi Metselaar, Hjalmar Permentier, et al.. Lactococcus lactis as expression host for the biosynthetic incorporation of tryptophan analogues in recombinant proteins. Biochemical Journal, 2007, 409 (1), pp.193-198. ⟨10.1042/BJ20070909⟩. ⟨hal-00478844⟩