FGSC #5443

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Reporting Genes: Has been replaced by strain number: 9999

Species: crassa

Allele: su201-8;td201

Alternate Strain Number: td201-5A

Depositor: FJD

Linkage Group: --;IIR

Mating Type: A

Species Number: 10

Deposit Sheet ↗

Genes

Locus	Cultural Requirements	Link Group	Type
trp-3	IIR. Right of fl (2 to 6%). Left of rip-1 (9%) and un-5(10%) (816, PB). (1166). Uses tryptophan (685); strains carrying some alleles also use indole (4). Structural gene for tryptophan synthetase (1167), called tryptophan desmolase in early literature. Tryptophan synthetase catalyzes three reactions: indoleglycerol-phosphate -> tryptophan, indole tryptophan, and indoleglycerol-phosphate <-> indole (Fig. 11). In Neurospora, all three reactions are catalyzed by a single protein, which is specified by a single gene (645, 1167). Mutants lack indoleglycerol-phosphate -> tryptophan activity but differ with respect to the other activities; e.g., strains carrying trp-3 allele (td141 are blocked in indoleglycerol-phosphate utilization but can use indole; trp-3 (td100) can synthesize indole but not convert it to tryptophan; trp-3 (td140) lacks all three activities. (See references 582 and 1049 for citations and characteristics of other mutants.) Used extensively for studies of gene structure in relation to enzymatic activity (257, 582 and references therein, 1167). The active enzyme is a homooligomer (645) thought to have two domains (644 and references therein). Biochemical studies of complementation between alleles: in vivo (582, 583) and in vitro (1048 and references therein). Complementation maps (4, 5, 9 and references therein, 582). Fine-structure maps (5, 540, 582, 1049). Reviewed as example of gene fusion (218). trp-3 mutant C83 provided the first proved example in Neurospora of gene-controlled loss of enzyme activity (685); trp-3 mutant S1952 provided the first example of allele-specific suppression restoring functional wild-type-like enzyme (1166). Allele td140 is supersuppressible (954, 955). Certain classes of trp-3mutants are osmotic remediable (583). Called td and tryp-3.	IIR	B
su(trp-3td201)-1	VIIR. Between met-7 (18%) and arg-10 (7%) (1174). Right of ssu-1 (10 to 13%) (954). Allele specific. Suppresses missense allele td201, but not eight other alleles (td1, td6, td7, td16, td37R, td71, tdl38R, and td141) (1174). Also does not suppress td2, td3, or td24 (910). A suppressed mutant has a low level of tryptophan synthetase activity, allowing slow growth on minimal medium. Enzyme activity is due to a protein physically like the wild-type enzyme (1174, 1175). Strains carrying the suppressor alone, without td201, grow slightly slower than wild type (910). The suppressor is effective when in another nucleus from td201 in a forced heterokaryon between noncomplementing alleles (td16;su plus td2Ol;su+) (910). Called Su-1 or Su-1td201 in reference 954, su-YS in reference 910, and su1(201) in reference 1173.	VIIR	B