title: Localized tufts of fibrils on Staphylococcus epidermidis NCTC 11047 are comprised of the accumulation-associated protein.
abstract: Staphylococcus epidermidis is both a human skin commensal and an opportunistic pathogen, causing infections linked to implanted medical devices. This paper describes localized tufts of fibrillar appendages on a subpopulation (25%) of wild-type (WT) S. epidermidis NCTC 11047 cells. The fibrils (122.2 +/- 10.8 nm long) are usually in a lateral position on the cells. Fibrillar (Fib(+)) and nonfibrillar (Fib(-)) subpopulations were separated (enriched) by 34 sequential partitions of WT cells between a buffer phase and a hexadecane phase. Following enrichment, hydrophobic cells from the hexadecane phase comprised 70% Fib(+) cells and the less hydrophobic cells from the buffer phase entirely comprised Fib(-) cells. The Fib(+) and Fib(-) subpopulations did not revert on subculture (34 times) on solid medium. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cell surface proteins from WT, Fib(+), and Fib(-) cells revealed two high-molecular-mass proteins (280 kDa and 230 kDa) on the WT and Fib(+) cells that were absent from the Fib(-) cells. Amino acid sequencing revealed that fragments of both the 280- and 230-kDa proteins had 100% identity to the accumulation-associated protein (Aap). Aap is known to cause biofilm formation if it is truncated by loss of the terminal A domain. Immunogold staining with anti-Aap antibodies labeled tuft fibrils of the WT and Fib(+) cells but not the cell surface of Fib(-) cells. The tufts were labeled with N-terminally directed antibodies (anti-A domain), showing that the fibrillar Aap was not truncated on the cell surface. Thus, the presence of full-length Aap correlated with the low biofilm-forming abilities of both WT and Fib(+) S. epidermidis NCTC 11047 populations. Reverse transcription-PCR showed that aap was transcribed in both Fib(+) and Fib(-) cells. We therefore propose that full-length Aap is expressed on cells of S. epidermidis NCTC 11047 as tufts of short fibrils and that fibril expression is regulated at a posttranscriptional level.
authors.affiliation: Faculty of Life Sciences, 1.800 Stopford Building, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.
authors.forename: Miriam A
authors.initials: MA
authors.lastname: Banner
authors.forename: John G
authors.initials: JG
authors.lastname: Cunniffe
authors.forename: Robin L
authors.initials: RL
authors.lastname: Macintosh
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Foster
authors.forename: Holger
authors.initials: H
authors.lastname: Rohde
authors.forename: Dietrich
authors.initials: D
authors.lastname: Mack
authors.forename: Emmy
authors.initials: E
authors.lastname: Hoyes
authors.forename: Jeremy
authors.initials: J
authors.lastname: Derrick
authors.forename: Mathew
authors.initials: M
authors.lastname: Upton
authors.forename: Pauline S
authors.initials: PS
authors.lastname: Handley
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers; D006801:Humans; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012867:Skin / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D011993:Recombinant Fusion Proteins