title: In the absence of Lgt, lipoproteins are shed from Streptococcus uberis independently of Lsp.
abstract: The role of lipoprotein diacylglyceryl transferase (Lgt) and lipoprotein signal peptidase (Lsp) responsible for processing lipoproteins was investigated in Streptococcus uberis, a common cause of bovine mastitis. In the absence of Lgt, three lipoproteins [MtuA (SUB0473), Hap (SUB1625) and an extracellular solute-binding protein (SUB0365)] were detected in extracellular locations. All were shown by Edman degradation analysis to be cleaved on the carboxy side of the LXXC lipobox. Detection of MtuA, a lipoprotein shown previously to be essential for infectivity and virulence, was used as a surrogate lipoprotein marker to locate and assess processing of lipoproteins. The absence of Lgt did not prevent location of MtuA to the cell membrane, its location in the wild-type strain but, in contrast to the situation with wild-type, did result in a widespread location of this protein. In the absence of both Lgt and Lsp, MtuA was similarly released from the bacterial cell. In such strains, however, the cell-associated MtuA represented the full-length gene product, indicating that Lsp was able to cleave non-lipidated (lipo)proteins but was not responsible for their release from this bacterium.
authors.affiliation: Institute for Animal Health, Compton, Berkshire RG20 7NN, UK.
authors.forename: E L
authors.initials: EL
authors.lastname: Denham
authors.affiliation: Nuffield Department of Clinical Laboratory Sciences, Oxford University, John Radcliffe Hospital, Headington, Oxfordshire OX3 9DU, UK.
authors.forename: P N
authors.initials: PN
authors.lastname: Ward
authors.affiliation: School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Leigh
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D005260:Female; D008074:Lipoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008414:Mastitis, Bovine / Q000382:microbiology; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D012697:Serine Endopeptidases / Q000378:metabolism*; D013291:Streptococcus / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D014166:Transferases / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; C492462:MtuA protein, Streptococcus uberis; D014166:Transferases; D012697:Serine Endopeptidases; C026515:type I signal peptidase