Biology Faculty Articles

Title

A pilot-scale Expressed Sequence Tag analysis of Beauveria bassiana gene expression reveals a tripeptidyl peptidase that is differentially expressed in vivo

Document Type

Article

Publication Date

1-1-2004

Publication Title

Mycopathologia

Keywords

Beauveria bassiana, entomopathogen, expressed sequence tags, in vivo, protease, tripeptidyl peptidase

ISSN

0301-486X

Volume

158

Issue/No.

2

First Page

201

Last Page

209

Abstract

The entomopathogen Beauveria bassiana is a dimorphic fungus that displays an in vivo-specific, yeast-like parasitic phase. In order to study the transcriptome of B. bassiana during this unique developmental phase, we developed a method to harvest in vivo B. bassiana cells from infected Manduca sexta larvae. The infected hemolymph was collected just prior to insect death and subjected to gradient centrifugation, which allowed for separation of the B. bassiana in vivo-produced cells from remaining insect hemocytes. Total RNA was extracted from the harvested fungal cells and used to construct a cDNA library that is representative of B. bassiana gene expression in vivo. Expressed Sequence Tags (ESTs) were generated and led to the cloning of two protease genes. One of these proteases was identified as a tripeptidyl peptidase (Bb TPP). The Bb TPP protease was shown to be up-regulated during infection, and identification of a signal peptide suggested that the enzyme is secreted in the host hemolymph. Although its activity and role have yet to be characterized, the Bb TPP protease appears as a likely candidate for being involved in B. bassiana pathogenesis. The identification of this novel, up-regulated protease also suggests that random sequencing from our in vivo cDNA library may be a valuable step towards identifying biologically active metabolites produced in vivo by B. bassiana.

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