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Updated: Jun 23, 2026

Site-Specific Lysine Lactylation via Genetic Code Expansion in E. coli and Mammalian Cells
Published on: February 24, 2026
Selenomethionine incorporation in proteins expressed in Lactococcus lactis
Ronnie P-A Berntsson1, Nur Alia Oktaviani, Fabrizia Fusetti
1Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Abstract:
Lactococcus lactis is a promising host for (membrane) protein overproduction. Here, we describe a protocol for incorporation of selenomethionine (SeMet) into proteins expressed in L. lactis. Incorporation efficiencies of SeMet in the membrane protein complex OpuA (an ABC transporter) and the soluble protein OppA, both from L. lactis, were monitored by mass spectrometry. Both proteins incorporated SeMet with high efficiencies (>90%), which greatly extends the usefulness of the expression host L. lactis for X-ray crystallography purposes. The crystal structure of ligand-free OppA was determined at 2.4 A resolution by a semiautomatic approach using selenium single-wavelength anomalous diffraction phasing.
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