Correct option is B
Explanation-
Statement A - PerR functions as a major peroxide sensor in many Gram-positive bacteria. - CORRECT
PerR (Peroxide response regulator) is a well-known regulator in Gram-positive bacteria (e.g., Bacillus subtilis). It represses genes involved in oxidative stress defense and is sensitive to H₂O₂ (hydrogen peroxide).
Statement B - Extreme acidic pH induces RecA-mediated DNA damage, which in turn may induce virulence gene expression in some pathogenic bacteria. - CORRECT
Acidic stress can cause DNA damage, leading to RecA activation. RecA triggers the SOS response, which is known to enhance virulence factor expression in bacteria like E. coli and Salmonella.
Statement C - Induced expression of heat shock proteins neither protects the cells from heat nor plays a role in bacterial virulence. - INCORRECT
Heat shock proteins (HSPs) like GroEL, DnaK, HtpG protect cells from heat-induced denaturation of proteins. HSPs also play roles in virulence (e.g., aiding survival in host environments). This statement is factually incorrect.
Statement D - In Gram-negative bacteria, heat shock σ factor regulates the transcription of the major heat shock proteins.- CORRECT
The σ^32 (RpoH) factor regulates heat shock response in Gram-negative bacteria like E. coli. It activates genes encoding chaperones and proteases during heat stress.
Statement E - GroES is an ATP-dependent chaperonin but GroEL may function in ATP-independent manner.
GroEL and GroES both require ATP for proper chaperonin function. GroEL assists in protein folding in an ATP-dependent manner, along with GroES. This statement is partially incorrect.
Correct Combination:
The correct statements are:
A, B, D → Option b
