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 trehal ose concentration were measured in two mutants affected in components of th e cAMP-signalling pathway. tr-l (crisp-l), deficient in adenylyl cyclase ac tivity, and, mch (microcyclic conidiation), deficient in the regulatory sub unit of PKA. Rapid mobilisation of intracellular trehalose in the wild-type occurred, either at the onset of germination, or after a heat shock, and b y carbon starvation. Mutant cr-I failed to mobilise trehalose at germinatio n, but behaved almost normally after a heat shock, or during carbon starvat ion. 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 norma lly during a heat shock. These results are consistent with the involvement of cAMP in the activation of the neutral trehalase at the onset of germinat ion. However, the control of the enzyme under the other physiological condi tions which also promote mobilisation of intracellular trehalose was appare ntly independent of cAMP-signalling. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.