Localized tufts of fibrils on Staphylococcus epidermidis NCTC 11047 are comprised of the accumulation-associated protein.
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.
Banner
Miriam A
MA
Faculty of Life Sciences, 1.800 Stopford Building, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.
Cunniffe
John G
JG
Macintosh
Robin L
RL
Foster
Timothy J
TJ
Rohde
Holger
H
Mack
Dietrich
D
Hoyes
Emmy
E
Derrick
Jeremy
J
Upton
Mathew
M
Handley
Pauline S
PS
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
D001426:Bacterial Proteins; D017931:DNA Primers; D011993:Recombinant Fusion Proteins