FGSC #6030

Reporting Genes: ssu-1 nit-3

Species: crassa

Allele: WRN33;KGP1222

Alternate Strain Number: 823

Mutagen: UV

Depositor: GAM

Linkage Group: VIIR;IVR

Mating Type: A

Species Number: 10

Genetic Background: M

ref1: Perrine and Marzluf 1986 Current Genetics 10:677, https://doi.org/10.1007/bf00410916

Genes

Locus	Cultural Requirements	Link Group	Type
ssu-1	VIIR. Right of met-7 (14%). Left of nt (23%) and of missense suppressor su(trp-3td201)-1 (10%) (954). Allele WRN33 selected (953) as suppressor of nonsense mutation am(17), which may be either amber or ochre but cannot be UGA (956). Inserts tyrosine in the site where the wild type has glutamate (956). Used to identify suppressible alleles of aro(p), trp-1, trp-2, trp-3 (953, 144, 183), and ad-3B (749). Although perhaps the most efficient of known ssumutations, ssu-1 restores only about 20% of the wild-type amount of normal glutamate dehydrogenase in the double mutant with am allele (17) (reference 956).	VIIR	B
nit-3	IVR. Between met-5 (15%) and pyr-2 (2 to 9%) (1000, PB). (453) Cannot use nitrate as a nitrogen source, but uses nitrite, ammonia, hypoxanthine, or amino acids (28, 999). Structural gene for NADPH nitrate reductase (28) (Fig. 19). Allele 14789 apparently codes for an altered enzyme that cannot catalyze the whole electron transport sequence from NADPH to N03-, but can catalyze the terminal portion of this sequence, providing that a suitable electron donor (reduced viologen dye) is provided (999). See reference 198 for a model of interaction of nit-1 and nit-3 gene products. For regulation, see references 226, 999, and 1000. The nit-3+ gene has been cloned and is expressed in Escherichia coli (989).	IVR	B

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