Microbiology

In Need of Nutrients

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Science  30 Mar 2012:
Vol. 335, Issue 6076, pp. 1547
DOI: 10.1126/science.335.6076.1547-c

Gut pathogens such as E. coli and Salmonella are faced with several hurdles when trying to establish an infection: the recruitment of immune cells, the secretion of antimicrobial factors, and competition in the form of the billions of commensal bacteria that normally reside in our guts. As a result, the pathogens need to have a few tricks up their sleeve. Liu et al. now report on one such example, used by Salmonella enterica serovar Typhimurium, a pathogen that causes severe gastroenteritis in humans. In response to S. Typhimurium infection, neutrophils are recruited to the gut in mice and produce the antimicrobial protein calprotectin. Calprotectin functions by sequestering essential metals, such as zinc, thus limiting an important nutrient source for the invading pathogen. S. Typhimurium can overcome this, and compete with the commensal flora, however, because it expresses a high-affinity zinc transporter. Strains that lacked this transporter did not grow as well in the inflamed gut but were not at a disadvantage in the absence of inflammation. These results suggest that nutrient availability is a key factor in the establishment of gastrointestinal infections.

CREDIT: ROCKY MOUNTAIN LABORATORIES, NIAID, NIH

Cell Host Microbe 11, 227 (2012).

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