Molecular cloning and characterization of the cys-3 regulatory gene of Neurospora crassa.

Abstract

The regulatory gene cys-3+ controls the synthesis of a number of enzymes involved in sulfur metabolism. cys-3 mutants show a multiple loss of enzymes in different pathways of sulfur metabolism. The cys-3+ gene was isolated by transformation of an aro-9 qa-2 cys-3 inl strain with a clone bank followed by screening with the "sib selection" method. The library used (pRALl) contained inserts of Sau3a partial digest fragments of about 9 kilobases as well as the Neurospora qa-2+ gene. Double selection for qa-2+ and cys-3+ function was carried out. The transformants obtained with the isolated cys-3+ clone show recovery of the enzyme activities associated with the cys-3 mutation (e.g., arylsulfatase and sulfate permease). Restriction fragment length polymorphism experiments confirmed the identity of the clone. mRNA studies with Northern blots show that the expression of the cys-3+ gene is inducible. In contrast to cys-3+, the cys-3 (P22) mutant gene was not expressed at a higher level under sulfur-derepressed conditions.

Sulfur Availability and the SAC1 Gene Control Adenosine Triphosphate Sulfurylase Gene Expression in Chlamydomonas reinhardtii

“…The Met4 protein is a Leu-zipper-containing transcriptional activator of the bZIP type (Thomas et al, 1992;Kuras and Thomas, 1995). In Neurospora crassa the Cys3 protein, which is also a bZIP-type DNA-binding protein, serves as a positive activator of sulfur-regulated genes (Marzluf, 1968;Paietta et al, 1987;Paietta, 1992).…”

The Genomes of Three Uneven Siblings: Footprints of the Lifestyles of Three Trichoderma Species

“…The main component of the sulfur regulatory circuit is a positively acting bZIP transcription factor, which in yeast is a heterodimer consisting of two proteins, Met28p and Met4p (442)(443)(444). In filamentous fungi, like N. crassa and A. nidulans, one homodimeric bZIP activator (N. crassa CYS-3, A. nidulans MetR) is responsible for sulfur network regulation (445,446). However, recent studies revealed that A. nidulans and other members of the Eurotiales may possess exchangeable homo-/heterodimeric regulatory networks comprised of MetR and paralogous bZIP transcription factor MetZ (447).…”

Molecular cloning and analysis of the regulation of cys-14+, a structural gene of the sulfur regulatory circuit of Neurospora crassa.

“…One recent study to examine the operation of the sulfur control circuit involved the cloning and subsequent analysis of the expression of the cys-3+ control gene (21). To understand the sulfur regulatory circuit, it is obviously very * Corresponding author.…”