Whole Genome Resequencing Revealed the Effect of Helicase yqhH Gene on Regulating Bacillus thuringiensis LLP29 against Ultraviolet Radiation Stress

Abstract

Bacillus thuringiensis (Bt) is a widely used microbial pesticide. However, its duration of effectiveness is greatly shortened due to the irradiation of ultraviolet rays, which seriously hinders the application of Bt preparations. Therefore, it is of great importance to study the resistance mechanism of Bt to UV at the molecular level to improve the UV-resistance of Bt strains. In order to know the functional genes in the UV resistance, the genome of UV-induced mutant Bt LLP29-M19 was re-sequenced and compared with the original strain Bt LLP29. It was shown that there were 1318 SNPs, 31 InDels, and 206 SV between the mutant strain and the original strain Bt LLP29 after UV irradiation, which were then analyzed for gene annotation. Additionally, a mutated gene named yqhH, a member of helicase superfamily II, was detected as an important candidate. Then, yqhH was expressed and purified successfully. Through the result of the enzymatic activity in vitro, yqhH was found to have ATP hydrolase and helicase activities. In order to further verify its function, the yqhH gene was knocked out and complemented by homologous recombinant gene knockout technology. The survival rate of the knockout mutant strain Bt LLP29-ΔyqhH was significantly lower than that of the original strain Bt LLP29 and the back-complemented strain Bt LLP29-ΔyqhH-R after treated with UV. Meanwhile, the total helicase activity was not significantly different on whether Bt carried yqhH or not. All of these greatly enrich important molecular mechanisms of Bt when it is in UV stress.

Urea Cycle of Bacillus thuringiensis Affects Its Survival under UV Stress

“…Compared with the drastically decreased RocF activity, ArgG seemed to retain most of its activity, which seems to imply that the isofunctional enzymes of ArgG may be present in Bt. Organisms often have multiple replacement genes or proteins for important enzymes or proteins 27 In fact, according to the GO annotations of genome sequencing in our previous work, 25,26 two presumptive isofunctional genes (BSP001038 and BSP001049) were detected in Bt LLP29. In addition, because ArgG is a ratelimiting enzyme for arginine synthesis, its expression level is usually very low.…”

Comparative Genomic Analysis of a Methylorubrum rhodesianum MB200 Isolated from Biogas Digesters Provided New Insights into the Carbon Metabolism of Methylotrophic Bacteria

“…The original reading of the strain can be obtained from Genbank through the following login number: (code after uploading). The databases NR, Swiss-Prot, COG (orthologous cluster), KEGG, GO, and Carbohydrate Active Enzyme Database (CAZy) were used for protein function annotation [ 52 ]. RNA, virulence factors, and resistance genes were determined based on the core data sets in Rfam (database reference), virulence factors of pathogenic bacteria (VFDB), and Antibiotic Resistance Gene Database (ARDB).…”

Plant-Associated Bacillus thuringiensis and Bacillus cereus: Inside Agents for Biocontrol and Genetic Recombination in Phytomicrobiome

“…Bt insecticidal proteins possess susceptibility to a broad spectrum of environmental influences, among which ultraviolet (UV) rays are the most important [6,7]. Ultraviolet radiation causes shorter persistence of Bt under the field conditions [8] due to extensive bacterial DNA cleavage, in particular, double-strand breaks [9]. Unfortunately, it demands the repeated spraying of crops, and the cost of using Bt is rising.…”