Review Question - QID 214788

A 26-year-old man presents to the emergency department with a 2-day history of bloody diarrhea. He says that he went to a company picnic 3 days ago and tried a variety of different dishes. Since then, he has experienced abdominal discomfort, bloating, and bloody diarrhea. He denies fever, rash, or any systemic symptoms during this time. He is given a course of antibiotics and is discharged to recover at home. A week after this episode, he presents to his primary care physician because his wife is worried that he appears pale. Which of the following describes the mechanism of action of the toxin produced in this patient?