Search

In Neurospora crassa , blocking the function of the standard mitochondrial electron transport chain results in the induction of an alternative oxidase (AOX). AOX transfers electrons directly from ubiquinol to molecular oxygen. AOX serves as a model of retrograde regulation since it is encoded by a nuclear gene that is regulated in response to signals from mitochondria. The N. crassa transcription factors AOD2 and AOD5 are necessary for the expression of the AOX gene. To gain insight into the mechanism by which these factors function, and to determine if they have roles in the expression of additional genes in N. crassa , we constructed strains expressing only tagged versions of the proteins. Cell fractionation experiments showed that both proteins are localized to the nucleus under both AOX inducing and noninducing conditions. Furthermore, chromatin immunoprecipitation and high throughput sequencing (ChIP-seq) analysis revealed that the proteins are bound to the promoter region of the AOX gene under both conditions. ChIP-seq also showed that the transcription factors bind to the upstream regions of a number of genes that are involved in energy production and metabolism. Dependence on AOD2 and AOD5 for the expression of several of these genes was verified by quantitative PCR. The majority of ChIP-seq peaks observed were enriched for both AOD2 and AOD5. However, we also observed occasional sites where one factor appeared to bind preferentially. The most striking of these was a conserved sequence that bound large amounts of AOD2 but little AOD5. This sequence was found within a 310 bp repeat unit that occurs at several locations in the genome., (Copyright © 2017 Qi et al.)

The global push toward an efficient and economical biobased economy has driven research to develop more cost-effective applications for the entirety of plant biomass, including lignocellulosic crops. As discussed elsewhere (Karlsson M, Atanasova L, Funck Jensen D, Zeilinger S, in Heitman J et al. [ed], Tuberculosis and the Tubercle Bacillus, 2nd ed, in press), significant progress has been made in the use of polysaccharide fractions from lignocellulose, cellulose, and various hemicellulose types. However, developing processes for use of the lignin fraction has been more challenging. In this chapter, we discuss characteristics of lignolytic enzymes and the fungi that produce them as well as potential and current uses of lignin-derived products.