Ji‐Sook Hahn

Heat shock transcription factor (HSF) is an evolutionarily conserved protein that mediates eukaryotic transcriptional responses to stress. Although the mammalian stress-responsive HSF1 isoform is activated in response to a wide array of seemingly unrelated stresses, including heat shock, pharmacological agents, infection and inflammation, little is known about the precise mechanisms or pathways by which this factor is activated by many stressors. The baker's yeast Saccharomyces cerevisiae encode

2-Phenylethanol (2-PE), a fragrance compound with a rose-like odor, is widely used in perfumery and cosmetics. Here, we report the first metabolic engineering approach for 2-PE production in Saccharomyces cerevisiae. 2-PE can be produced from the catabolism of L-phenylalanine via Ehrlich pathway, consisting of transamination to phenylpyruvate by Aro9, decarboxylation to phenylacetaldehyde by Aro10, and reduction to 2-PE by alcohol dehydrogenases. We demonstrated that Ald3 is mainly responsible f

Hsf1 and Msn2/Msn4 transcription factors in Saccharomyces cerevisiae play important roles in cellular homeostasis by activating gene expression in response to multiple stresses including heat shock, oxidative stress and nutrient starvation. Although it has been known that nuclear import of Msn2 is inhibited by PKA-dependent phosphorylation, the mechanism for PKA-dependent regulation of Hsf1 is not well understood. Here we demonstrate that Yak1 kinase, which is under the negative control of PKA,

Heat shock transcription factor (HSF) mediates the transcriptional response of eukaryotic cells to heat, infection and inflammation, pharmacological agents, and other stresses. Although genes encoding heat shock proteins (HSPs) are the best characterized targets of HSF, recent genome-wide localization of Saccharomyces cerevisiae HSF revealed novel HSF targets involved in a wide range of cellular functions. One such target, the RPN4 gene, encodes a transcription factor that directly activates exp

The Slt2/Mpk1 mitogen-activated protein kinase (MAPK) cell integrity pathway is involved in maintenance of cell shape and integrity during vegetative growth and mating in Saccharomyces cerevisiae. Slt2 is activated by dual phosphorylation of a threonine and tyrosine residue in response to several environmental stresses that perturb cell integrity. Negative regulation of Slt2 is achieved via dephosphorylation by two protein-tyrosine phosphatases, Ptp2 and Ptp3, and a dual specificity phosphatase,

Microbial lactic acid (LA) production under acidic fermentation conditions is favorable to reduce the production cost, but circumventing LA toxicity is a major challenge. A d-LA-producing Saccharomyces cerevisiae strain JHY5610 is generated by expressing d-lactate dehydrogenase gene (Lm. ldhA) from Leuconostoc mesenteroides, while deleting genes involved in ethanol production (ADH1, ADH2, ADH3, ADH4, and ADH5), glycerol production (GPD1 and GPD2), and degradation of d-LA (DLD1). Adaptive laborat

Rim15 kinase, a downstream effector of PKA and TORC1 signaling pathways, initiates the quiescent program upon nutrient starvation via induction of genes whose expression depends on transcription factors Msn2, Msn4, and Gis1. Here, we demonstrate that Rim15 also induces expression of Hsf1 target genes upon glucose depletion by both transcriptional activation and stabilization of the transcripts. Rim15 phosphorylates Hsf1 in vitro, suggesting that Rim15 might directly activate Hsf1. In addition, I

Genes encoding a homolog of Escherichia coli OxyR (oxyR) and an alkyl hydroperoxide reductase system (ahpC and ahpD) have been isolated from Streptomyces coelicolor A3(2). The ahpC and ahpD genes constitute an operon transcribed divergently from the oxyR gene. Expression of both ahpCD and oxyR genes was maximal at early exponential phase and decreased rapidly as cells entered mid-exponential phase. Overproduction of OxyR in Streptomyces lividans conferred resistance against cumene hydroperoxide

Nod1 and Nod2 proteins play important roles in mammalian innate immune responses as intracellular sensors for bacterial peptidoglycan. Nod1 and Nod2 share structural homology with many R proteins involved in plant disease resistance. It has been demonstrated that plant Hsp90 and its co-chaperone RAR1 are implicated in R-mediated disease resistance. Here the Chp-1 gene encoding a mammalian homologue of plant RAR1 was identified as a new target for transcriptional activation by heat shock factor 1

Streptomyces coelicolor produces three distinct catalases to cope with oxidative and osmotic stresses and allow proper growth and differentiation. The major vegetative catalase A (CatA) is induced by H(2)O(2) and is required for efficient aerobic growth. In order to investigate the H(2)O(2)-dependent regulatory mechanism, an H(2)O(2)-resistant mutant (HR40) overproducing CatA was isolated from S. coelicolor A3(2). Based on the genetic map location of the mutated locus in HR40, the wild type catR

In Saccharomyces cerevisiae, Haa1 and War1 transcription factors are involved in cellular adaptation against hydrophilic weak acids and lipophilic weak acids, respectively. However, it is unclear how these transcription factors are differentially activated depending on the identity of the weak acid. Using a field-effect transistor (FET)-type biosensor based on carbon nanofibers, in the present study we demonstrate that Haa1 and War1 directly bind to various weak acid anions with different affini

Bacterial genes responsible for poly(3-hydroxybutyrate) (PHB) biosynthesis were targeted to plant peroxisomes by adding a carboxy-terminal targeting sequence. The enzymes evidently were transported into peroxisomes, retained their catalytic activity, and reacted with peroxisomally available precursors because PHB synthesis in transgenic plant cells was localized to peroxisomes. Up to 2 mg/g fresh weight PHB was produced in suspension cultures of Black Mexican Sweet maize cells after biolistic tr

Aro80, a member of the Zn(2)Cys(6) family proteins, activates expression of the ARO9 and ARO10 genes involved in catabolism of aromatic amino acids in response to aromatic amino acids that act as inducers. ARO9 and ARO10 are also under the control of nitrogen catabolite repression, but the direct roles for GATA factors, Gat1 and Gln3, in this regulation have not yet been elucidated. Here, we demonstrate that Aro80 is constitutively bound to its target promoters and activated by inducers at the l