Microbiology

Brightly Glows the Sexy Parasite

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Science  28 May 2004:
Vol. 304, Issue 5675, pp. 1213
DOI: 10.1126/science.304.5675.1213a

In plants, and a few groups of microorganisms, Ca2+- dependent protein kinases (CDPKs) translate externally triggered calcium signals into cellular responses. Plasmodium malaria parasites have many CDPKs, and intracellular Ca2+ regulates the parasite's sexual development. Billker et al. looked at the process of Plasmodium gametocyte differentiation, after consumption of parasitized blood by mosquitoes, using a parasite reporter strain engineered to contain a fluorescent cytosolic calcium sensor. Within seconds of entering the mosquito gut, parasite differentiation starts. Host-derived xanthurenic acid shifts the microbial cytosolic pH from 7.4 to pH 8.0, triggering a Ca2+ burst that activates CDPK, possibly via guanylyl cyclase. Fifteen minutes later fertilization occurs. It appears that the type of CDPK programs male and female development, with CDPK4 apparently being male-specific. Importantly, CDPKs do not occur in the mammalian hosts of malaria parasites, making them interesting targets for anti-malarial drug discovery. — CA

Cell 117, 503 (2004

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