FGSC #8389

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Reporting Genes: pyr-3 pyr-1; arg-1 arg-6; aga

Species: crassa

Allele: DFC8, DFC33; CD145, CD29; UM906

Alternate Strain Number: 2277-2a

Depositor: RHD

Linkage Group: IVR, IVR; IL, IR; VIIR

Mating Type: a

Species Number: 10

Genetic Background: SL

ref1: Davis 1975 Genetics 93:557-575, https://doi.org/10.1093/genetics/93.3.557

Deposit Sheet ↗

Genes

Locus	Cultural Requirements	Link Group	Type
pyr-3	IVR. Right of the T(NM152) left breakpoint and of T(S1229); hence, right of arg-14. Left of his-5 (1%) (238, 808). (482) Requires uracil or other pyrimidine (683). Growth inhibited by purine nucleosides and nucleotides (825). Structural gene for pyrimidine-specific carbamyl phosphate synthase (CPS) and aspartate carbamyl transferase (ACT; also abbreviated ATC) (456, 850) (Fig. 20). Mutants may lack either or both activities, e.g., those carrying alleles KS43 (CPS+ ACT-), KS20 (CPS- ACT+), and KS11 (CPS- ACT-) (1140). Unlike Saccharomyces, no feedback-insensitive CPS+ ACT+ mutants of Neurosporahave been discovered (A. Radford, unpublished data). Some mutants have kinetically altered aspartate carbamyl transferase (456, 880). Used extensively for studies of channeling and relation of gene structure to the two enzyme activities (236). Normally, carbamyl phosphate produced by pyr-3+ is used solely for pyrimidine synthesis, and carbamyl phosphate produced by arg-2+ and arg-3+ is used for arginine synthesis, the enzymes being in different organelles; however, a deficiency of the next enzyme in either pathway permits overflow of carbamyl phosphate into the other pathway (reviewed in reference 236). Hence, CPS- ACT+ alleles are suppressed by arg-12s (246), and CPS+' ACT- alleles can be selected as suppressors of arg-2and arg-3 (658, 887, and references therein). Some of the CPS+ ACT- mutations, called pyr-su-arg, suppress the arginine requirement but retain enough aspartate carbamyl transferase activity that they have no detectable pyrimidine requirement (877, 881). arg-13, arg-4, arg-5, arg-6, and am partly suppress CPS- ATC+ alleles (see reference 660). Fine-structure map (851, 1050). Fertility of interallelic crosses is variable and often very poor (658). Complementation between CPS- ACT+ and CPS+ ACT- mutants (246) and between some pairs of CPS+ ACT- mutants is good; otherwise, complementation is poor (849, 1159). Complementation maps (658, 849, 877, 1159). Mutational analysis (852). Direction of translation, based on enzyme types of polar mutants, is from CPS to ACT (850). Allele 37815(t) is heat sensitive (34°C versus 25 C) (68). Allele 1298 is C02 remediable (191, 192). Strain KS12, a pyr-1 pyr-3 double mutant, was originally called pyr-5 (see reference 346). The different classes of pyr-3 alleles have been called M (CPS-P-less), N (ACT-less), and MN (lacks both activities).	IVR	B
aga	VIIR. Between wc-1 (2%) and arg-10 (24 to 27%) (240, 697). Presumed structural gene for arginase (240, 697) (see Fig. 10). Unable to form ornithine from arginine; arginine is thus unable to satisfy the proline requirement of pro-3 in a pro-3 aga double mutant. Prototrophic single mutants develop polyamine requirement in the presence of arginine. This is due to feedback inhibition of ornithine biosynthesis by arginine, combined with a catabolic block in ornithine formation from arginine (240). Siderophore production is severely reduced in the absence of ornithine in the triple mutant aga arg-5 ota, which has been used to study iron transport (1146, 1147) and to obtain mutants defective in siderophore uptake (G.W. Charlang and N.P. Williams, personal communication); see sit.	VIIR	B
arg-1	Uses arginine but not precursors.	IL	B
arg-6	Uses ornithine, citrulline or arginine.	IR	B
pyr-1	IVR. Right of psi (4%) and T(ALS159) (808, PB). Left of pdx-1 (<1 to 10%) (692). (482) Requires uracil or other pyrimidine. Lacks dihydroorotate dehydrogenase activity (133, 134) (Fig. 20). All ascospores from pyr-1 x pyr-1crosses are white if cross is on medium containing 0.1 mg of uracil per ml; they are black if the cross is on medium containing 1.0 mg/ml (632).	IVR	B