Correct option is C
The correct answer is: (3) The A subunit of the lethal toxin is a protease that cleaves the members of MAP kinase kinase family.
Explanation:
Anthrax is caused by the bacterium Bacillus anthracis, which is a gram-positive bacterium, not a gram-negative one. The A subunit of the lethal toxin of Bacillus anthracis is a protease called LF (Lethal Factor), which cleaves members of the MAPKK (Mitogen-Activated Protein Kinase Kinase) family, disrupting signaling pathways and leading to cell death. The B subunit, which helps in delivering the A subunit into the cell, is called protective antigen (PA), not lethal factor.
Information Booster:
The lethal toxin consists of two parts: protective antigen (PA) (B subunit) and lethal factor (LF) (A subunit). PA is responsible for binding to receptors and facilitating the entry of LF into the host cell.
Lethal factor (LF), the A subunit, is a protease that cleaves the MAPK kinase family, particularly MEK1 and MEK2, which disrupts cellular signaling and leads to apoptosis or necrosis.
Edema toxin has a different A subunit, edema factor (EF), which is an adenylate cyclase enzyme, and together with PA forms a toxin that causes fluid accumulation and edema.
The A subunits of the lethal toxin and edema toxin are not identical. Lethal toxin contains LF, while edema toxin contains EF.
Additional Knowledge:
Gram-negative bacterium (option 1) is incorrect. Bacillus anthracis is gram-positive.
The B subunit of anthrax toxin is known as the lethal factor (option 2) is incorrect because the B subunit is protective antigen (PA), not lethal factor.
The lethal toxin and edema toxin consist of identical A subunits (option 4) is incorrect because the A subunits of these two toxins are different: Lethal factor for lethal toxin and Edema factor for edema toxin.
