In the absence of Lgt, lipoproteins are shed from Streptococcus uberis independently of Lsp.
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.
Denham
E L
EL
Institute for Animal Health, Compton, Berkshire RG20 7NN, UK.
Ward
P N
PN
Nuffield Department of Clinical Laboratory Sciences, Oxford University, John Radcliffe Hospital, Headington, Oxfordshire OX3 9DU, UK.
Leigh
J A
JA
School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, UK.
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
D001426:Bacterial Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; C492462:MtuA protein, Streptococcus uberis; D014166:Transferases; D012697:Serine Endopeptidases; C026515:type I signal peptidase