Gene: cysteine
cysteine
locus: cys
locus_name: cysteine
organism_type: B
chromosome_number:
chromosome_side:
link_group:
cultural_requirements: Cysteine auxotrophs are characterized as being unable to use inorganic sulfate but able to grow on either cysteine or methionine (721). Some cys mutants can use sulfite or thiosulfate. The sulfur permease mutants cys-13 and cys-14 are exceptions, having no demonstrable requirement. Cysteine mutant strains tend to accumulate secondary mutations in the pathway, suggesting that some double-mutant combinations have a selective advantage over single-mutant strains (721). Unambiguous definition of loci based on map location is thus important, and care must be taken that derived stocks carry the original cysmutation. Cysteine and methionine loci provide several examples of closely linked pairs of genes: cys-1 cys-2, cys-5 cys-11, and met-7 met-9. With at least two cys mutants (cys-3, cys-5), and possibly others, ascospore maturation and recovery of cys progeny requires that crossing medium be supplemented, even when the protoperithecial parent is cys+. Cysteine mutants grown on limiting supplement show a shortened period of circadian conidiation rhythm (329, 333). Partial suppressors of leu-4 which originate as double-mutant microcolonies on minimal medium are leaky cys mutants of various types (425); see leu.
enzyme_id:
anid_name:
near_l:
near_r:
neu_name:
supplement: cysteine or methionine
image_url:
Strains
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References
