Cell signaling and functions mediated by a serine-threonine phosphatase regulatory subunit and related proteins in Neurospora crassa

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In this thesis work, I investigated cell functions mediated by the calcineurin B (CNB-1) subunit in Neurospora crassa. I studied how the mutations in the various EF-hand domains of CNB-1 result in diverse phenotypes under stress conditions, including calcium (Ca2+) stress, thermotolerance, and regulation of the circadian clock in N. crassa. Furthermore, I established genetic interaction of cnb-1 with the nca-2, hsp80, crz-1, frequency (frq-1), and white-collar (wc-1) genes in the regulation the heat shock, Ca2+ stress and circadian clock in N. crassa. Moreover, I found that the upregulation of nca-2 during Ca2+ stress requires the binding of the transcription factor calcineurin responsive zinc-finger-1 (CRZ-1) to an 8 bp nucleotide sequence 5ʹ-ACCGCGCC-3ʹ, which is about 234 bp upstream of the ATG start codon of the nca-2. Furthermore, CRZ-1 physically binds to two other 8 bp nucleotide sequences 5´-CCTTCACA-3´ and 5ʹ-AGCGGAGC-3ʹ, which are about 1167 bp and 679 bp upstream of the ATG start codon in the promoter of hsp80 under heat shock conditions in N. crassa. Therefore, the calcineruin-Crz-1 signaling cascade is important for cell survival under Ca2+ stress and heat shock conditions in N. crassa.
Supervisor: Ranjan Tamuli