University of Sussex
Browse
__smbhome.uscs.susx.ac.uk_tjk30_Documents_28thNov.pdf (732.51 kB)

Differential proteolytic activation of the Bacillus thuringiensis Cry41Aa parasporin modulates its anticancer effect

Download (732.51 kB)
journal contribution
posted on 2023-06-09, 20:01 authored by Wided Souissi, Arnold Kaloki, Stuart Etherington, Barbara Domanska, Michelle WestMichelle West, Neil CrickmoreNeil Crickmore
Bacillus thuringiensis (Bt) is a gram positive spore forming bacterium which produces intracellular protein crystals toxic to a wide variety of insect larvae and is the most commonly used biological pesticide worldwide. More recently, Bt crystal proteins known as parasporins have been discovered, that have no known insecticidal activity but target some human cancer cells exhibiting strong cytocidal activities with different toxicity spectra and varied activity levels. Parasporin-3, also called Cry41Aa, has only been shown to exhibit cytocidal activity towards HL-60 (Human promyelocytic leukemia cells) and HepG2 (Human liver cancer cells) cell lines after being proteolytically cleaved. In order to understand this activation mechanism various mutations were made in the N-terminal region of the protein and the toxicity against both HepG2 and HL-60 cell lines was evaluated. Our results indicate that only N-terminal cleavage is required for activation and that N-terminally deleted mutants show some toxicity without the need for proteolytic activation. Furthermore we have shown that the level of toxicity towards the two cell lines depends on the protease used to activate the toxin. Proteinase K-activated toxin was significantly more toxic towards HepG2 and HL-60 than trypsin-activated toxin. N-terminal sequencing of activated toxins showed that this difference in toxicity is associated with a difference of just two amino acids (serine and alanine at positions 59 and 60 respectively) which we hypothesize occlude a binding motif.

History

Publication status

  • Published

File Version

  • Accepted version

Journal

Biochemical Journal

ISSN

0264-6021

Publisher

Portland Press

Issue

24

Volume

476

Page range

3805-3816

Department affiliated with

  • Biochemistry Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2020-01-02

First Open Access (FOA) Date

2020-12-24

First Compliant Deposit (FCD) Date

2019-12-20

Usage metrics

    University of Sussex (Publications)

    Categories

    No categories selected

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC