Single-molecule imaging of interaction between dextran and glucosyltranferase from Streptococcus sobrinus

Kuniyoshi Kaseda, Hiroaki Yokota, Yoshiharu Ishii, Toshio Yanagida, Tetsuyoshi Inoue, Kazuhiro Fukui, Takao Kodama

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Using total internal reflection fluorescence microscopy, we directly observed the interaction between dextran and glucosyltransfease I (GTF) of Streptococcus sobrinus. Tetramethylrhodamine (TMR)-labeled GTF molecules were individually imaged as they were associating with and then dissociating from the dextran fixed on the glass surface in the evanescent field. Similarly dynamic behavior of TMR-labeled dextran molecules was also observed on the TGF-fixed surface. The duration of the stay on the surface (dwell time) was measured for each of these molecules by counting the number of video frames that had recorded the image. A histogram of dwell time for a population of several hundred molecules indicated that the GTF-dextran interaction obeyed an apparent first-order kinetics. The rate constants estimated for TMR- labeled GTF at pH 6.8 and 25°C in the absence and presence of sucrose were 9.2 and 12.3 s-1, respectively, indicating that sucrose accelerated the dissociation of GTF from dextran. However, the accelerated rate was still much lower than the catalytic center activity of GTF (≥25 s-1) under comparable conditions.

Original languageEnglish
Pages (from-to)1162-1166
Number of pages5
JournalJournal of bacteriology
Volume182
Issue number4
DOIs
Publication statusPublished - Feb 2000
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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