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Journal of Bacteriology, July 2000, p. 3649-3654, Vol. 182, No. 13
Center for Oral Biology and Department of
Microbiology and Immunology, University of Rochester School of
Medicine and Dentistry, Rochester, New York 14642
Received 31 January 2000/Accepted 4 April 2000
Oral actinomycetes produce fructosyltransferase (FTF) enzymes which
convert sucrose into polymers of D-fructose, known as levans, and these polymers are thought to contribute to the persistence and virulence of the organisms. A gene encoding FTF was isolated from
Actinomyces naeslundii WVU45; the deduced amino acid
sequence showed significant similarity to known levansucrases of
gram-negative environmental isolates but was less similar to FTFs from
gram-positive bacteria. A transcriptional start site was mapped by
primer extension 70 bp 5' from the putative start codon. Promoter
fusions to a chloramphenicol acetyltransferase gene were used to
confirm that there was a functional promoter driving ftf
expression and to show that sequences located 86 to 218 bp upstream of
the transcription initiation site were required for optimal
ftf expression. Quantitative slot blot analysis against
total RNA from cells grown on different sugars or from different growth
phases revealed that ftf was constitutively transcribed.
Thus, the A. naeslundii FTF is more similar in primary sequence and the regulation of expression to levansucrases of gram-negative bacteria than gram-positive bacteria.
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Characterization of the Fructosyltransferase Gene
of Actinomyces naeslundii WVU45
*
Corresponding author. Mailing address: Center for Oral
Biology and Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave., Rochester, NY 14642. Phone: (716) 275-0381. Fax: (716) 473-2679. E-mail: robert_burne{at}urmc.rochester.edu.
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