Ferrochelatase is a conserved downstream target of the blue light-sensing White collar complex in fungi

Abstract

Light is a universal signal perceived by organisms, including fungi, in which light regulates common and unique biological processes depending on the species. Previous research has established that conserved proteins, originally called White collar 1 and 2 from the ascomycete Neurospora crassa, regulate UV/blue light sensing. Homologous proteins function in distant relatives of N. crassa, including the basidiomycetes and zygomycetes, which diverged as long as a billion years ago. Here we conducted microarray experiments on the basidiomycete fungus Cryptococcus neoformans to identify light-regulated genes. Surprisingly, only a single gene was induced by light above the commonly used twofold threshold. This gene, HEM15, is predicted to encode a ferrochelatase that catalyses the final step in haem biosynthesis from highly photoreactive porphyrins. The C. neoformans gene complements a Saccharomyces cerevisiae hem15Δ strain and is essential for viability, and the Hem15 protein localizes to mitochondria, three lines of evidence that the gene encodes ferrochelatase. Regulation of HEM15 by light suggests a mechanism by which bwc1/bwc2 mutants are photosensitive and exhibit reduced virulence. We show that ferrochelatase is also light-regulated in a white collar-dependent fashion in N. crassa and the zygomycete Phycomyces blakesleeanus, indicating that ferrochelatase is an ancient target of photoregulation in the fungal kingdom.

Regulation of Conidiation by Light in Aspergillus nidulans

“…However, unlike N. crassa, the study of the light-regulated processes has not been approached in detail in the Aspergilli but light sensing, including the regulation by red light of conidiation, was described in A. nidulans and other fungi many years ago (Tan 1974;Mooney and Yager 1990;Bayram et al 2010;Rodriguez-Romero et al 2010). Complete expression analysis has been performed by microarray hybridization experiments with different fungi (Rosales-Saavedra et al 2006;Chen et al 2009;Greenwald et al 2010;Idnurm and Heitman 2010). In N. crassa Figure 6 Light-dependent induction of the brlA gene is mediated by FlbA, FlbB, and FlbC.…”

Calcineurin Colocalizes with P-Bodies and Stress Granules during Thermal Stress in Cryptococcus neoformans

“…The resulting strain, LK214, was used to construct LK303 by integrating plasmid pLKB88, which encodes mCherryPub1. A strain expressing GFP-Hem15 and mCherry-Cna1 (LK282) was generated by integrating plasmid pLKB60 into strain AI132 (24). A strain expressing DsRed-SKL and GFP-Cna1 (LK296) was made by integrating plasmid pLKB39 into strain AI100 (23).…”

“…We excluded the possibility that the Cna1 puncta represent mitochondria or peroxisomes, which were previously shown to exhibit a punctate appearance in Cryptococcus. Cells coexpressing mCherry-Cna1 with GFP-Hem15 as a mitochondrial marker (24) or with GFPCna1 with DsRed-SKL as a peroxisomal marker (23) exhibited little or no colocalization of calcineurin with these punctate intracellular organelles at 37°C (see Fig. S3 in the supplemental material).…”

Cryptococcus neoformans and Cryptococcus gattii, the Etiologic Agents of Cryptococcosis

“…It is unknown whether darkness represents a specific signal and the relevant genes are also unknown. Although genes for heme biosynthesis and iron uptake are induced by light, the light-sensing mutants do not have phenotypes that indicate any change in these properties (Idnurm and Heitman 2010). Hence, the three best-established virulence traits and growth or stress phenotypes are unaffected, and further analysis may enable discoveries about virulence factors operating in Cryptococcus species.…”