Purine-Requiring Auxotrophs of Coprinus lagopus (sensu Buller)

Abstract

SUMMARYThe allelic relationships between a series of independently-induced adenine mutants of Coprinus Zagopus were investigated, and limited complementation maps of three of the loci constructed. By means of nutritional tests and a search for aminoimidazole accumulants in the mycelium the adenine loci were correlated with steps in the purine biosynthetic pathway. Four loci can be assigned to (unknown) steps preceding closure of the imidazole ring, two others to specific steps occurring after closure of the ring. One of these latter represents a deficiency in the enzyme adenylosuccinase.

Selection markers for transformation of the sequenced reference monokaryon Okayama 7/#130 and homokaryon AmutBmut of Coprinopsis cinerea

“…Ten of these genes have been mapped onto 7 linkage groups [50][51][52]. Though, in our analysis only four to possibly seven genes (ade2, ade8, ade1, ade5, and possibly ade4, ade9, and ade12) from only four linkage groups could be assigned to specific positions on sequenced chromosomes (Table 1), using as additional information their clearly defined biochemical reactions (cases ade1, ade5 [49]) or approximate positions in the de novo purine biosynthesis pathway (ade2, ade3, ade4 and ade8 all act prior to imidazole ring closure [49]) and/or their linkages (ade2, ade3, ade5, ade8, ade9 and ade12) to other unquestionably identifiable gene functions on the classical C. cinerea map ( [33,[50][51][52]; see footnote of Table 1). However, no other convincing candidate for gene ade8 were found in appropriate distance to the A locus on chromosome 1 ( Table 1).…”

“…GARSs are members of the ATP-grasp superfamily of enzymes with an [49]) and, 9 cM away from the A mating type locus, ade9 [51,52] which appears to function as a regulatory enzyme rather than within the direct de novo pathway of purine biosynthesis [49] and might therefore be a dihydrofolate reductase gene for THF production located 752 kb downstream to A43β (recombination rate is then 83 kb/cM) with potential cross-pathway effects between de novo purine biosynthesis and THF-mediated C1, histidine and methionine metabolisms [42,46]. A gene with potential GART function (step 3 in de novo purine biosynthesis) as one candidate for the unmapped gene ade4 functioning in the pathway prior to imidazole ring closure [49,52] is present 1932 kb downstream of A43β, closer to the telomere. Chromosome 2 = classical linkage group III with trp1, trp3, ade2…”

“…(with function prior to AIR ring closure [49]) and ade12 (0.2 cM apart from ade2 [52] = an estimated distance of 5.6 to 6.6 kb [20,33] which could point to CC1G_01221T0 for S-adenosylmethionine synthase at position Chr_2:1,226,385-1,227,850 or CC1G_01223T0 for diadenosine polyphosphate hydrolase and related proteins of the histidine triad (HIT) family at position Chr_2: 1,231,397-1,230,670 as potential candidates for ade12).…”

“…Chromosome 3 = classical linkage group G with trp2 [51,52], pcc1 [33], and, 16 cM distal to trp2 [51,52], ade3 unidentified here with a function prior to AIR ring closure [49]. Chromosome 5…”

“…= classical linkage group IV with ade1 with CAIR synthase function [49]. Chromosome 6 (with a gene for a FGAMS function as another ade4 candidate) and chromosome 7…”