Differential HSC70 expression during asexual development of Neurospora crassa.
The constitutive and the heat-shock-induced expression of members of heat-shock protein families changed during vegetative development and conidiation of Neurospora crassa as determined by two-dimensional gel electrophoresis. Western blot and ELISA analyses revealed the highest amounts of the constitutive heat-shock protein 70 (HSC70) in conidiating aerial hyphae and dormant conidia. During conidial germination the amount of HSC70 decreased and subsequently increased during vegetative growth. Stationary mycelia and young aerial hyphae exhibited the lowest HSC70 level. The stationary-phase-dependent decrease in HSC70 was accompanied by a concomitant increase in its nuclear localization, whereas no significant changes in the amount of nuclear HSC70 were found during aerial hyphae development. The cAMP content during aerial hyphae development was inversely correlated with that of HSC70. To examine possible causal relations between HSC70 expression and cAMP content, the adenylate-cyclase-deficient mutant crisp (cr-1) was analysed, which exhibits low concentrations of endogenous cAMP. This mutant, however, showed a lower constitutive HSC70 level, compared to the bdA strain. Treatment of the bd strain and cr-1 mutant with 20 microM 8-bromo-cAMP did not result in significant changes of the constitutive HSC70 level, but in the level of heat-induced HSC/HSP70. In a developmental mutant (acon-2) which is defective in a differentiation step toward conidiation, the expression of HSC70 in aerial hyphae was delayed until the first proconidial chains were observed. It is concluded that the differential expression of HSC/HSP70 does not depend on different nuclear levels of HSC70 or on changes in cAMP concentrations, but rather on developmental genes controlling conidiation.
Fracella
Franco
F
Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen,PO Box 33 04 40, D-28334 Bremen,Germany.
Scholle
Carl
C
Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen,PO Box 33 04 40, D-28334 Bremen,Germany.
Kallies
Andreas
A
Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen,PO Box 33 04 40, D-28334 Bremen,Germany.
Häfker
Thomas
T
Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen,PO Box 33 04 40, D-28334 Bremen,Germany.
Schröder
Torsten
T
Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen,PO Box 33 04 40, D-28334 Bremen,Germany.
Rensing
Ludger
L
Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen,PO Box 33 04 40, D-28334 Bremen,Germany.
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000235:genetics; D002352:Carrier Proteins / Q000096:biosynthesis*; D002467:Cell Nucleus / Q000378:metabolism; D000242:Cyclic AMP / Q000096:biosynthesis*; D003593:Cytoplasm / Q000378:metabolism; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D018869:Heat-Shock Response / Q000502:physiology; D009154:Mutation; D009492:Neurospora crassa / Q000254:growth & development / Q000378:metabolism*
D002352:Carrier Proteins; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; D000262:Adenylyl Cyclases