FGSC #4321

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Reporting Genes: trp-1;cot-1;al-3;ylo-1

Species: crassa

Allele: 10575;C102(t);RP100;Y30539y

Alternate Strain Number: 9333

Depositor: DDP

Linkage Group: III;IV;V;VI

Mating Type: A

Species Number: 10

Opposite Mating Type: 4322

Deposit Sheet ↗

Genes

Locus	Cultural Requirements	Link Group	Type
al-3	VR. Between his-1 and inl (1%) (1119, PB). Carotenoids deficient (398). Reported to lack geranylgeranyl pyrophosphate synthetase activity and is blocked in soluble fraction, consistent with lesion between isopentenyl pyrophosphate and geranylgeranyl pyrophosphate (445), but can still produce farnesyl pyrophosphate (445) and steroids (398). (See Fig. 9.) This evidence contradicts in vivo labeling results that indicate a lesion between prephytoene pyrophosphate and phytoene (572). Strains carrying allele Y234M470 (al-3ros), formerly called rosy (49), become partially pigmented but are readily distinguished from the wild type. ylo-1 can be scored in combination with al-3ros (Y234M470) (PB). Strains carrying other alleles (e.g., RP100) (1119) are white with a trace of pink pigment. Biosynthetic pathway for carotenoids. It is thought that the same prenyl transferase catalyzes all the steps from dimethylallyl pyrophosphate to geranylgeranyl pyrophosphate (444; R.W. Harding, personal communication), and it has been proposed that a separate prenyl transferase converts dimethylallyl pyrophosphate to farnesyl pyrophosphate for sterol synthesis (445). The conversion of phytoene to the various carotenoid pigments involves a series of dehydrogenations, cyclizations, and other reactions. There must also be a cis/trans isomerization analogous to that found in tomato (842). The sequence of some of these steps is still uncertain; the pathway must branch, and there may be alternate routes to some of the products. See references 228, 443, 444, 842 and citations therein for proposed sequences. al-1 is probably blocked in phytoene dehydrogenase (398). It is not known whether this enzyme catalyzes the whole series of dehydrogenations. al-2 is reported blocked between geranylgeranyl pyrophosphate and phytoene (445) and between prephytoene pyrophosphate and phytoene (572). al-3 is alternately reported blocked between isopentenyl pyrophosphate and geranylgeranyl pyrophosphate (445) and between prephytoene pyrophosphate and phytoene (572), but it is not blocked in the production of farnesyl pyrophosphate or sterols (398, 445). ylo-1 is evidently blocked in a late step, probably either in the conversion of lycopene to 3,4-dehydrolycopene or in the conversion of either torulene or gamma-carotene to neurosporaxanthin (see citations in reference 398).	VR	B
cot-1	IVR. Between pan-1 (2%) and his-4 (1 to 6%) (692, 812, 816). Extremely colonial at 34°C, but completely normal growth, morphology, and fertility at 25°C and below. Linear growth is maximum at 24°C (374). Becomes colonial at 32°C; colonies from ascospores or conidia are viable and continue to grow slowly with dense branching, but do not conidiate. They quickly resume normal growth when shifted to a permissive temperature (692, 1068). Recessive in duplications (808); apparent dominance in heterokaryons (374) may have resulted from a shift in nuclear ratios. Used in studies of septation and branching (202), growth-inhibiting mucopolysaccharide (878, 879), and sulfate transport (641). Cell wall analysis (374). Growth is stimulated by lysine or arginine (0.1 mM) on glucose media at high temperatures (615). Because of high viability and tightly restricted growth at restrictive temperatures and normality at 25°C, cot-1 mutants have valuable technical applications. For example, crosses homozygous for cot-1 have been used in combination with sorbose for experiments with rec genes, where high-density ascospore platings are required for precise quantitative analysis of intralocus recombination (e.g., references 165, 997, and 1070). In another application, when shifted up after initial growth at the permissive low temperature, cot-1hyphae assume a "bottle brush" appearance with small side branches (692). This has been used to select uvs mutants by subsurface survival on UV-irradiated plates containing p-aminobenzoic acid (938; D.E.A. Catcheside, personal communication). cot-1 conidia or ascospores from cot-1 x cot-1crosses are used for replication in a protocol involving transfer by filter paper (615). For suppressors of cot-1, see gul.	IVR	B
ylo-1	VIL. Between cys-1 (8%) and ad-1 (6%). Probably right of Bml (2%) (1012, PB). (381). Yellow carotenoids (381). Affects synthesis of neurosporaxanthin (4'-apo-beta'-caroten-4'-oic acid); citations in reference 398. Lesion probably involves the conversion of lycopene to 3,4-dehydrolycopene or the conversion of either torulene or gamma-carotene to neurosporaxanthin (398 and references therein) (Fig. 9). Resembles the orange wild type in young cultures, but color differences become clear with age. Expressed in both conidia and mycelia. Undefined modifiers affect intensity. Fails to complement with many of the al-1 and al-2 albino strains (R.E. Subden, personal communication).	VIL	B
trp-1	IIIR. Between ad-2 (1 to 7%) and ro-2 (2 to 12%) (11, 219, 812). Linked to fpr-3 (< 1%) (550). (504). Uses tryptophan or indole (1060); strains carrying some alleles can also use anthranilate; others cannot (4). trp-1+ and trp-2+ gene products together form an enzyme aggregate with three activities: anthranilate synthetase, phosphoribosyl-anthranilate isomerase, and indoleglycerol-phosphate synthetase (181, 260) (Fig. 11). trp-1 codes for the beta subunit of the aggregate (546); it specifies phosphoribosyl-anthranilate isomerase, indoleglycerol-phosphate synthetase, and collaboratively the glutamine amino transferase activity of anthranilate synthetase (29, 181, 502). Strains carrying different alleles differ in lacking one or more of the three activities, e.g., trp-1 (allele 15) lacks all three activities; trp-1 (20) lacks only phosphoribosyl- anthranilate isomerase, trp-1C (1) lacks only anthranilate synthetase, trp-1 (25) lacks both phosphoribosyl-anthranilate isomerase and indoleglycerol-phosphate synthetase, etc. (259). (To avoid confusion, note that in reference 259 and related papers, the same "allele number" may be used for a trp-2 mutation, a trp-1 mutation [non-anthranilate-utilizing], and a trp-1Cmutation [anthranilate utilizing]; mutations of the last class are listed by FGSC as trp-1 with the allele number prefixed by C.) Strains carrying different alleles differ in their ability to form aggregates (181, 259). Association between trp-1 and trp-2products is essential for glutamine-dependent anthranilate synthetase activity but not the other two activities (181). The trp-1 gene has been cloned (545, 925), sequenced (925), and reintroduced into Neurospora by transformation (925). It is only partially expressed in E. coli. Fine-structure maps (10, 259). Complementation maps (10, 163). Reviewed as example of gene fusion (218). Nonsense allele used to demonstrate restoration of normal enzyme aggregate by supersuppressors (183). Alleles that accumulate anthranilate are scorable by blue fluorescence under long-wave UV after 2 to 5 days of growth on minimal medium plus indole (10 µg /ml), 34°C (814, 816). Aging cultures may produce brown pigment; blue fluorescence disappears as pigment forms.	IIIR	B