# Cloning, Heterologous Expression, and Antifungal Activity Evaluation of a Novel Truncated TasA Protein from Bacillus amyloliquefaciens BS-3

## TL;DR

Scientists cloned and tested a shortened TasA protein from a Bacillus strain, finding it strongly inhibits fungal growth in rubber trees.

## Contribution

The study reports the shortest functional TasA variant to date with enhanced antifungal properties and structural stability.

## Key findings

- The truncated TasA protein showed 98.6% inhibition of Colletotrichum acutatum and 64.77% inhibition of Alternaria heveae.
- TasA completely suppressed spore germination at 60 μg/mL for C. acutatum and Oidium heveae.
- AlphaFold3 analysis indicated that truncation improved TasA's structural stability.

## Abstract

TasA gene, encoding a functional amyloid protein critical for biofilm formation and antimicrobial activity, was cloned from the endophytic strain Bacillus amyloliquefaciens BS-3, isolated from rubber tree roots. This study identified the shortest functional TasA variant (483 bp, 160 aa) reported to date, featuring unique amino acid substitutions in conserved domains. Bioinformatics analysis predicted a signal peptide (1–27 aa) and transmembrane domain (7–29 aa), which were truncated to optimize heterologous expression. Two prokaryotic vectors (pET28a and pCZN1) were constructed, with pCZN1-TasA expressed solubly in Escherichia coli Arctic Express at 15 °C, while pET28a-TasA formed inclusion bodies at 37 °C. Purified recombinant TasA exhibited potent antifungal activity, achieving 98.6% ± 1.09 inhibition against Colletotrichum acutatum, 64.77% ± 1.34 against Alternaria heveae. Notably, TasA completely suppressed spore germination in C. acutatum and Oidium heveae Steinmannat 60 μg/mL. Structural analysis via AlphaFold3 revealed that truncation enhanced protein stability. These findings highlight BS-3-derived TasA as a promising biocontrol agent, providing molecular insights for developing protein-based biopesticides against rubber tree pathogens.