Wobble Editing of Cre-box by Unspecific CRISPR/Cas9 Causes CCR Release and Phenotypic Changes in Bacillus pumilus

oleh: Yingxiang Wang, Yingxiang Wang, Linfeng Cao, Linfeng Cao, Meiying Bi, Meiying Bi, Sicheng Wang, Sicheng Wang, Meiting Chen, Meiting Chen, Xingyu Chen, Xingyu Chen, Ming Ying, Ming Ying, Lei Huang, Lei Huang

Format: Article
Diterbitkan: Frontiers Media S.A. 2021-08-01

Deskripsi

CRISPR-associated Cas9 endonuclease (CRISPR/Cas9) systems are widely used to introduce precise mutations, such as knocking in/out at targeted genomic sites. Herein, we successfully disrupted the transcription of multiple genes in Bacillus pumilus LG3145 using a series of unspecific guide RNAs (gRNAs) and UgRNA:Cas9 system-assisted cre-box editing. The bases used as gRNAs shared 30–70% similarity with a consensus sequence, a cis-acting element (cre-box) mediating carbon catabolite repression (CCR) of many genes in Bacillus. This triggers trans-crRNA:Cas9 complex wobble cleavage up/downstream of cre sites in the promoters of multiple genes (up to 7), as confirmed by Sanger sequencing and next-generation sequencing (NGS). LG3145 displayed an obvious CCR release phenotype, including numerous secondary metabolites released into the culture broth, ∼ 1.67 g/L white flocculent protein, pigment overflow causing orange-coloured broth (absorbance = 309 nm), polysaccharide capsules appearing outside cells, improved sugar tolerance, and a two-fold increase in cell density. We assessed the relationship between carbon catabolite pathways and phenotype changes caused by unspecific UgRNA-directed cre site wobble editing. We propose a novel strategy for editing consensus targets at operator sequences that mediates transcriptional regulation in bacteria.