title: Active lipoprotein precursors in the Gram-positive eubacterium Lactococcus lactis.
abstract: Lipid-modified proteins play important roles at the interface between eubacterial cells and their environment. The importance of lipoprotein processing by signal peptidase II (SPase II) is underscored by the fact that this enzyme is essential for viability of the Gram-negative eubacterium Escherichia coli. In contrast, SPase II is not essential for growth and viability of the Gram-positive eubacterium Bacillus subtilis. This could be due to alternative amino-terminal lipoprotein processing, which was shown previously to occur in SPase II mutants of B. subtilis. Alternatively, uncleaved lipoprotein precursors might be functional. To explore further the importance of lipoprotein processing in Gram-positive eubacteria, an SPase II mutant strain of Lactococcus lactis was constructed. Although some of the 39 (predicted) lactococcal lipoproteins, such as PrtM and OppA, are essential for growth in milk, the growth of SPase II mutant L. lactis cells in this medium was not affected. Furthermore, the activity of the strictly PrtM-dependent extracellular protease PrtP, which is required for casein degradation, was not impaired in the absence of SPase II. Importantly, no alternative processing of pre-PrtM and pre-OppA was observed in cells lacking SPase II. Taken together, these findings show for the first time that authentic lipoprotein precursors retain biological activity.
authors.affiliation: Department of Genetics, University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, Kerklaan 30, 9751 NN Haren, The Netherlands.
authors.forename: Roelke
authors.initials: R
authors.lastname: Venema
authors.forename: Harold
authors.initials: H
authors.lastname: Tjalsma
authors.forename: Jan Maarten
authors.initials: JM
authors.lastname: van Dijl
authors.forename: Anne
authors.initials: A
authors.lastname: de Jong
authors.forename: Kees
authors.initials: K
authors.lastname: Leenhouts
authors.forename: Girbe
authors.initials: G
authors.lastname: Buist
authors.forename: Gerard
authors.initials: G
authors.lastname: Venema
mesh_terms: D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000502:physiology; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000502:physiology; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000502:physiology; D002455:Cell Division; D013294:Lactococcus lactis / Q000737:chemistry* / Q000254:growth & development; D008074:Lipoproteins / Q000096:biosynthesis* / Q000502:physiology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000502:physiology; D008969:Molecular Sequence Data; D011498:Protein Precursors; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals; C093804:PrtM protein, Lactococcus lactis; C046506:oligopeptide-binding protein, bacteria; D016282:Aspartic Acid Endopeptidases; C095652:signal peptidase II