Mobilisation of trehalose in mutants of the cyclic AMP signalling pathway, cr-1 (CRISP-1) and mcb (microcycle conidiation), of Neurospora crassa.

The influence of the cAMP-signalling pathway on the metabolism of trehalose in Neurospora crassa was investigated. The changes in intracellular trehalose concentration were measured in two mutants affected in components of the cAMP-signalling pathway: cr-1 (crisp-1), deficient in adenylyl cyclase activity, and mcb (microcyclic conidiation), deficient in the regulatory subunit of PKA. Rapid mobilisation of intracellular trehalose in the wild-type occurred, either at the onset of germination, or after a heat shock, and by carbon starvation. Mutant cr-1 failed to mobilise trehalose at germination, but behaved almost normally after a heat shock, or during carbon starvation. On the other hand, the levels of trehalose in mcb fell to values much lower than in the wild-type at germination, but accumulated trehalose normally during a heat shock. These results are consistent with the involvement of cAMP in the activation of the neutral trehalase at the onset of germination. However, the control of the enzyme under the other physiological conditions which also promote mobilisation of intracellular trehalose was apparently independent of cAMP-signalling.