Send to

Choose Destination
FEMS Microbiol Lett. 2011 Sep;322(1):51-9. doi: 10.1111/j.1574-6968.2011.02329.x. Epub 2011 Jun 27.

Molecular basis of indole production catalyzed by tryptophanase in the genus Prevotella.

Author information

Department of Dental Pharmacology, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.


Indole is most commonly known as a diagnostic marker and a malodorous chemorepellent. More recently, it has been recognized that indole also functions as an extracellular signaling molecule that controls bacterial physiology and virulence. The gene (tnaA) for tryptophanase, which produces indole, ammonia, and pyruvate via β-elimination of L-tryptophan, was cloned from Prevotella intermedia ATCC 25611 and recombinant TnaA was purified and enzymatically characterized. Analysis by reverse transcriptase-mediated PCR showed that the gene was not cotranscribed with flanking genes in P. intermedia. The results of gel-filtration chromatography suggested that P. intermedia TnaA forms homodimers, unlike other reported TnaA proteins. Recombinant TnaA exhibited a K(m) of 0.23 ± 0.01 mM and k(cat) of 0.45 ± 0.01 s(-1). Of 22 Prevotella species tested, detectable levels of indole were present in the culture supernatants of six, including P. intermedia. Southern hybridization showed that tnaA-positive signals were present in the genomic DNA from the six indole-producing strains, but not the other 16 strains tested. The indole-producing strains, with the exception of Prevotella micans, formed a phylogenetic cluster based on trees constructed using 16S rRNA gene sequences, which suggested that tnaA in P. micans might have been transferred from other Prevotella species relatively recently.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Silverchair Information Systems Icon for Wiley
Loading ...
Support Center