Cloning, sequence, and photoregulation of al-1, a carotenoid biosynthetic gene of Neurospora crassa.

Abstract

Carotenoid biosynthesis is regulated by blue light during growth of Neurospora crassa mycelia. We have cloned the al-1 gene of N. crassa encoding the carotenoid-biosynthetic enzyme phytoene dehydrogenase and present an analysis of its structure and regulation. The gene encodes a 595-residue polypeptide that shows homology to two procaryotic carotenoid dehydrogenases. RNA measurements showed that the level of al-1 mRNA increased over 70-fold in photoinduced mycelia. Transcription run-on studies indicated that the al-1 gene was regulated at the level of initiation of transcription in response to photoinduction. The photoinduced increase of al-1 mRNA levels was not observed in two Neurospora mutants defective in all physiological photoresponses. Analysis of cosmid containing al-1 and of a translocation strain with a breakpoint within al-1 indicated that al-1 transcription proceeds towards the centromere of linkage group I of N. crassa.

Molecular cloning and functional expression in E. coli of a novel plant enzyme mediating ξ‐carotene desaturation

“…First, CRT-I type of phytoene desaturases have been cloned from the bacteria Rhodobacter capsulatus [13], Erwinia uredovora and E. herbicola (crtl genes) [14,15] and from the fungus Neurospora crassa (aLl gene) [16] and sequenced. Then, the genes encoding phytoene desaturases from cyanobacteria [12,17], green algae and plants [11,18,19] have been isolated (pds genes).…”

Nitrogen regulation of blue light-inducible genes in Neurospora crassa

“…Their gene products are necessary for photocarotenogenesis (Harding & Turner,198 l), phototropism of perithecial beaks (Harding & Melles, 1984), photoinduction of protoperithecia (Degli-Innocenti & Russo, 19844 and photoinduction of circadian rhythms in bd mutants (Russo, 1988). In mycelia of wc-1 and wc-2 mutant strains, transcription of al, bli and con genes (Sommer et al, 1989;Nelson et al, 1989;Schmidhauser et al, 1990;Lauter & Russo, 1991) is not photoinducible.…”

“…The con clones were provided by Charles Yanofsky (Stanford University) (Berlin & Yanofsky, 1985 ;Roberts et al, 1988). The al-2 and bli genes were described previously (Schmidhauser et al, 1990;Sommer et al, 1989). In case of al-2, an 800 bp cDNA fragment cloned in pTJS430 was used as hybridization probe.…”

“…crassa, wc-1 and wc-2, are impaired in light regulation. The products of wc-1 and wc-2 are required for all photoeffects tested so far (Harding & Turner, 1981;Harding & Melles, 1984;Degli-Innocenti & Russo, 1984a, b ;Russo, 1988;Sommer et al, 1989 ;Nelson et al, 1989 ;Schmidhauser et al, 1990;Nawrath & Russo, 1990;Lauter & Russo, 199 l), with the exception of photophosphorylation of proteins . Wc-1 and Wc-2 are thought to be regulatory factors responsible for the light t ransduc t ion pathway.…”

“…al-1 encodes the enzyme phytoene dehydrogenase (Schmidhauser et al, 1990) Russo, 1986). Two regulatory mutants of N .…”