Comparative Analysis of the Global Transcriptomic Response to Oxidative Stress of Bacillus anthracis htrA-Disrupted and Parental Wild Type Strains

Abstract

We previously demonstrated that the HtrA (High Temperature Requirement A) protease/chaperone active in the quality control of protein synthesis, represents an important virulence determinant of Bacillus anthracis. Virulence attenuation of htrA-disrupted Bacillus anthracis strains was attributed to susceptibility of ΔhtrA strains to stress insults, as evidenced by affected growth under various stress conditions. Here, we report a comparative RNA-seq transcriptomic study generating a database of differentially expressed genes in the B. anthracishtrA-disrupted and wild type parental strains under oxidative stress. The study demonstrates that, apart from protease and chaperone activities, HtrA exerts a regulatory role influencing expression of more than 1000 genes under stress. Functional analysis of groups or individual genes exhibiting strain-specific modulation, evidenced (i) massive downregulation in the ΔhtrA and upregulation in the WT strains of various transcriptional regulators, (ii) downregulation of translation processes in the WT strain, and (iii) downregulation of metal ion binding functions and upregulation of sporulation-associated functions in the ΔhtrA strain. These modulated functions are extensively discussed. Fifteen genes uniquely upregulated in the wild type strain were further interrogated for their modulation in response to other stress regimens. Overexpression of one of these genes, encoding for MazG (a nucleoside triphosphate pyrophosphohydrolase involved in various stress responses in other bacteria), in the ΔhtrA strain resulted in partial alleviation of the H2O2-sensitive phenotype.

Structural analysis of the housecleaning nucleoside triphosphate pyrophosphohydrolase MazG from Mycobacterium tuberculosis

“…MazG belongs to the all-α NTP pyrophosphatases (Galperin et al, 2006), which exist from viruses and bacteria to humans (Song et al, 2015;Rihtman et al, 2019;Zaide et al, 2020;Huang et al, 2021;Wood et al, 2021;Han et al, 2022). As a housecleaning enzyme, MazG functions at the cell nucleotide metabolism by degrading the non-canonical NTPs, preventing mutagenesis and DNA damage.…”

“…As a housecleaning enzyme, MazG functions at the cell nucleotide metabolism by degrading the non-canonical NTPs, preventing mutagenesis and DNA damage. Moreover, MazG helps bacteria in response to oxidative stress in E. coli (Han and Eiteman, 2018), B. anthracis (Zaide et al, 2020), and Mycobacterium (Shi et al, 2019). In addition, many studies show that MazG is critical in regulating the DNA damage response in mycobacterium (Lu et al, 2010;Lyu et al, 2013;Fan et al, 2018;Shi et al, 2019).…”

Inhalable vaccine of bacterial culture supernatant extract mediates protection against fatal pulmonary anthrax

“…However, one previous study showed that deleting htrA did not appear to affect the level of PA produced in the Sterne strain [ 30 ]. Since HtrA can play a regulatory role and affect the expression of more than 1000 genes [ 31 ], and its effect on secretory proteins is obviously different in various media conditions [ 32 ], it is speculated that knockout of htrA plus other protease gene or genes may cause complex regulatory mechanisms such as compensatory protein degradation under the culture condition of our study. Nevertheless, the detailed reason for this phenomenon remains to be explored.…”

Overview of Human HtrA Family Proteases and Their Distinctive Physiological Roles and Unique Involvement in Diseases, Especially Cancer and Pregnancy Complications

“…Prokaryotic HtrAs play an essential role in bacterial virulence and survival under cellular or environmental stress [ 10 , 11 , 12 , 13 , 14 , 15 ]. Plant HtrAs maintain the photosynthetic machinery by acting as a chaperone in the assembly of photosystem II and as a protease in the degradation of photo-damaged reaction centres [ 2 ].…”