Question

1. A-B toxins are very commonly produced by bacterial pathogens. Answer the questions below. You are encouraged to use examples to illustrate your point.

What is the function of the A subunit?
What is the function of the B subunit?
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2.You have just sequenced the genome of a novel bacterial pathogen that causes gastrointestinal disease in cows. Your colleagues has indicated that a possible pathogenicity associated island has been detected in the DNA sequencing data.

What is a pathogenicity associated island?

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Answer 1

Answer 1

AB toxins or type III exotoxins type toxins that are classified as two component proteins which are secreted by pathogenic bacteria and are known to be toxic to host cells.

It is comprised of two subunits :

1) A subunit : This subunit is an active component of AB toxin that mediates toxic effects against host cell.

2) B subunit: This subunit is the binding subunit that helps in binding to host cell.

First B subunit of AB exotoxin recognizes the target cell and then A-B toxin is endocytosed then A subunit mediates toxic effects.

Answer 2

Pathogenicity associated islands (PAIs) or Pathogenicity islands (PIs) are the genomic islands or we can say the mobile DNA elements that encodes for virulence or pathogenic factors. It is found to be present in genome of pathogenic organisms and absent in non-pathogenic organisms.