TITLE:
Gene Expression Modulation of Two Biosynthesis Pathways via Signal Transduction in Cochliobolus heterostrophus
AUTHORS:
Ofir Degani
KEYWORDS:
Cochliobolus heterostrophus; Cytochrome P450-Dependent Benzoate Hydroxylase; G-Protein; Isoflavone Reductase; Maize; MAPK; Signal Transduction
JOURNAL NAME:
Advances in Bioscience and Biotechnology,
Vol.5 No.4,
March
12,
2014
ABSTRACT: G-protein-linked pathways have evolved to
allow responses to extracellular agonists (hormones, neurotransmitters, odors,
chemoattractants, light and nutrients) in eukaryotic cells, ranging from
simpler systems, including yeasts, filamentous fungi and slime molds, to more
complex organisms, such as mammals. Although the role of G-protein and mitogen-activated protein kinase (MAPK) in filamentous fungi has been studied for
over a decade, downstream elements are less known, and the study of target
genes has evolved mainly in recent years. Here, we examined the involvement of G-protein subunits and MAPK in controlling the expression of two distinct target
genes. These genes were selected from an array database according to
their unique expression profile and the role of closely related genes found in other Ascomycetes. One of these genes is BPH,
which encodes the enzyme responsible
for cytochrome P450-dependent benzoate hydroxylation in microsomes. The other
gene is CIPA, which encodes isoflavone reductase (IfR), an enzyme involved in the synthesis
of phytoalexin, which catalyzes an
intermediate step in pisatin biosynthesis. The expression profile of these two
genes was determined in a series of
signaling deficiency mutants that were grown on different media using a DNA microarray.
Comparison of the expression profile in the two wild type strains and mutants
deficient in the G-protein α or β subunits or in MAPK, revealed a unique control
mechanism for the BPH and CIPA genes. The two genes are highly
expressed during the infection of the host plant leaves and may associate with the fungal response to the host. Signaling
via G-protein or MAPK was shown to be related to cascades that altered the
expression of these genes in response to the growth condition. This work
demonstrates that signal transduction pathways are controlling genes that, although sharing
an environmental dependent response, participate in distinct biosynthesis pathways. Moreover,
the transcriptional profile may point to distinct and shared roles of the
signaling components.