Listeria monocytogenes is a facultative gram-positive bacterium that replicates efficiently within the cytosol of the host cell. It can cause severe disease (listeriosis) in pregnant and immunocompromised individuals, but little has been known about its mechanisms of intracellular survival and replication. In the October 17 Science, Mary O'Riordan and colleagues at the University of California, Berkeley, show that Listeria requires host-derived lipoic acid for intracellular growth and virulence (Science, 302: 462-464, October 17, 2003).
O'Riordan et al. generated L. monocytogenes lacking the lipoate protein ligase LplA1 and observed that this mutant was defective for growth, specifically in the host cytosol, and was less virulent in animals by a factor of 300. When they grew the ΔlplA1 strain intracellularly, the E2 subunit of pyruvate dehydrogenase (PDH—a major target for LplA1) lacked a critical lipoyl modification, which suggested that abortive growth was due to loss of PDH function.
"Some other bacterial pathogens, ...
