J Biol Chem. 2013 Mar 22. [Epub ahead of print]
Optogenetic modulation of an adenylate cyclase in Toxoplasma gondii demonstrates a requirement of the parasite cAMP for host-cell invasion and stage differentiation
Hartmann A, Arroyo-Olarte RD, Imkeller K, Hegemann P, Lucius R, Gupta N
Humboldt University, Berlin, Germany.
Successful infection and transmission of the obligate intracellular parasite Toxoplasma gondii depends on its ability to switch between fast-replicating tachyzoite (acute) and quiescent bradyzoite (chronic) stages. An induction of cAMP in the parasitized host cells has been proposed to influence parasite differentiation. It is unknown whether the parasite or host cAMP is required to drive this phenomenon. An unequivocal research on cAMP-mediated signaling in such intertwined systems also requires a method for an efficient and spatial control of the cAMP pool in the pathogen or in the enclosing host cell. We have resolved these critical concerns by expressing a photo-activated adenylate cyclase that allows a light-sensitive control of the cytosolic cAMP in T. gondii, or in its human host cells. Using this method, we reveal multiple roles of the parasite-derived cAMP in host-cell invasion, stage-specific expression and asexual differentiation. An optogenetic method provides many desired advantages such as, it (i) allows rapid, transient and efficient induction of cAMP in the extracellular/intracellular and acute/chronic stages; (ii) circumvents difficulties often faced in cultures i.e., poor diffusion, premature degradation, steady activation and/or pleiotropic effects of cAMP agonists and antagonists; (iii) involves genetically-encoded enzyme expression, hence, inheritable to the progeny; and (iv) allows conditional and spatiotemporal control of cAMP. Importantly, a successful optogenetic application in Toxoplasma also illustrates its wider utility to many other genetically amenable two-organism systems such as, symbiotic and pathogen-host interactions.
PMID: 23525100 [PubMed - as supplied by publisher]