NisB is required for the dehydration and NisC for the lanthionine formation in the post-translational modification of nisin.
Nisin produced by Lactococcus lactis subsp. lactis is a 34-residue antibacterial polypeptide and belongs to a group of post-translationally modified peptides, lantibiotics, with dehydrated residues and cyclic amino acids, lanthionines. These modifications are supposed to be made by enzymes encoded by lanB and lanC genes, found only in biosynthetic operons encoding lantibiotics. To analyse the extent of modification, His-tagged nisin precursors were expressed in nisB and nisC mutant strains. The His-tagged nisin precursors were purified from the cytoplasm of the cells, as lack of NisB or NisC activity impaired translocation of the nisin precursor. The purified His-tagged polypeptides were analysed with trypsin digestion followed by nisin bioassay, SDS-PAGE, N-terminal sequencing and mass spectroscopy. According to the results, nisin precursors from the strain lacking NisB activity were totally unmodified, whereas nisin precursors from the strain lacking NisC activity, but having NisB activity, were dehydrated and devoid of normal lanthionine formation. This is the first experimental evidence showing that NisB is required for dehydration and NisC for correct lanthionine formation in nisin maturation.
Koponen
Olli
O
Department of Applied Chemistry and Microbiology1 and Institute of Biotechnology2, Viikki Biocentre, University of Helsinki, Finland.
Tolonen
Marja
M
Department of Applied Chemistry and Microbiology1 and Institute of Biotechnology2, Viikki Biocentre, University of Helsinki, Finland.
Qiao
Mingqiang
M
Department of Applied Chemistry and Microbiology1 and Institute of Biotechnology2, Viikki Biocentre, University of Helsinki, Finland.
Wahlström
Gudrun
G
Department of Applied Chemistry and Microbiology1 and Institute of Biotechnology2, Viikki Biocentre, University of Helsinki, Finland.
Helin
Jari
J
Department of Applied Chemistry and Microbiology1 and Institute of Biotechnology2, Viikki Biocentre, University of Helsinki, Finland.
Saris
Per E J
PEJ
Department of Applied Chemistry and Microbiology1 and Institute of Biotechnology2, Viikki Biocentre, University of Helsinki, Finland.
D000409:Alanine / Q000031:analogs & derivatives* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003681:Dehydration; D006639:Histidine / Q000378:metabolism; D013294:Lactococcus lactis / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009561:Nisin / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D013440:Sulfides
D001426:Bacterial Proteins; D008565:Membrane Proteins; C079126:NisB protein, Lactococcus lactis; D013440:Sulfides; D009561:Nisin; D006639:Histidine; C001520:lanthionine; D000409:Alanine