Canonical and noncanonical roles of Hop1 are crucial for meiotic prophase in the fungus Sordaria macrospora.

We show here that in the fungus Sordaria macrospora, the meiosis-specific HORMA-domain protein Hop1 is not essential for the basic early events of chromosome axis development, recombination initiation, or recombination-mediated homolog coalignment/pairing. In striking contrast, Hop1 plays a critical role at the leptotene/zygotene transition which is defined by transition from pairing to synaptonemal complex (SC) formation. During this transition, Hop1 is required for maintenance of normal axis structure, formation of SC from telomere to telomere, and development of recombination foci.

RNAi-Related Dicer and Argonaute Proteins Play Critical Roles for Meiocyte Formation, Chromosome-Axes Lengths and Crossover Patterning in the Fungus .

RNA interference (RNAi) is a cellular process involving small RNAs that target and regulate complementary RNA transcripts. This phenomenon has well-characterized roles in regulating gene and transposon expression. In addition, Dicer and Argonaute proteins, which are key players of RNAi, also have functions unrelated to gene repression.

A single Ho-induced double-strand break at the MAT locus is lethal in Candida glabrata.

Mating-type switching is a complex mechanism that promotes sexual reproduction in Saccharomycotina. In the model species Saccharomyces cerevisiae, mating-type switching is initiated by the Ho endonuclease that performs a site-specific double-strand break (DSB) at MAT, repaired by homologous recombination (HR) using one of the two silent mating-type loci, HMLalpha and HMRa. The reasons why all the elements of the mating-type switching system have been conserved in some Saccharomycotina, that do not show a sexual cycle nor mating-type switching, remain unknown.

Genome editing in the yeast Nakaseomyces delphensis and description of its complete sexual cycle.

The environmental yeast Nakaseomyces delphensis is, phylogenetically, the closest known species to Candida glabrata, a major fungal pathogen of humans. C. glabrata is haploid and described as asexual, while N.

Efficient Mating-Type Switching in Candida glabrata Induces Cell Death.

Candida glabrata is an apparently asexual haploid yeast that is phylogenetically closer to Saccharomyces cerevisiae than to Candida albicans. Its genome contains three MAT-like cassettes, MAT, which encodes either MATa or MATalpha information in different strains, and the additional loci, HML and HMR. The genome also contains an HO gene homolog, but this yeast has never been shown to switch mating-types spontaneously, as S.

Comparative genomics of emerging pathogens in the Candida glabrata clade.

Background: Candida glabrata follows C. albicans as the second or third most prevalent cause of candidemia worldwide. These two pathogenic yeasts are distantly related, C.

A comparative proteomic approach to better define Deinococcus nucleoid specificities.

Compared to radiation-sensitive bacteria, the nucleoids of radiation-resistant Deinococcus species show a higher degree of compaction. Such a condensed nucleoid may contribute to the extreme radiation resistance of Deinococcus by limiting dispersion of radiation-induced DNA fragments. Architectural proteins may play a role in this high degree of nucleoid compaction, but comparative genomics revealed only a limited number of Deinococcus homologs of known nucleoid-associated proteins (NAPs) from other species such as Escherichia coli.

The deinococcal DdrB protein is involved in an early step of DNA double strand break repair and in plasmid transformation through its single-strand annealing activity.

The Deinococcus radiodurans bacterium exhibits an extreme resistance to ionizing radiation. Here, we investigated the in vivo role of DdrB, a radiation-induced Deinococcus specific protein that was previously shown to exhibit some in vitro properties akin to those of SSB protein from Escherichia coli but also to promote annealing of single stranded DNA. First we report that the deletion of the C-terminal motif of the DdrB protein, which is similar to the SSB C-terminal motif involved in recruitment to DNA of repair proteins, did neither affect cell radioresistance nor DNA binding properties of purified DdrB protein.

H2O2 activates the nuclear localization of Msn2 and Maf1 through thioredoxins in Saccharomyces cerevisiae.

The cellular response to hydrogen peroxide (H(2)O(2)) is characterized by a repression of growth-related processes and an enhanced expression of genes important for cell defense. In budding yeast, this response requires the activation of a set of transcriptional effectors. Some of them, such as the transcriptional activator Yap1, are specific to oxidative stress, and others, such as the transcriptional activators Msn2/4 and the negative regulator Maf1, are activated by a wide spectrum of stress conditions.

Combination of different molecular mechanisms leading to fluconazole resistance in a Candida lusitaniae clinical isolate.

We report on the underlying molecular mechanisms likely responsible for the high-level fluconazole resistance in a Candida lusitaniae clinical isolate. Fluconazole resistance correlated with overexpression of ERG11 and of several efflux pump genes, in particular, the orthologs of the Candida albicans MDR1, PDR16, CDR1, CDR2, and YOR1.

Role of Sho1p adaptor in the pseudohyphal development, drugs sensitivity, osmotolerance and oxidant stress adaptation in the opportunistic yeast Candida lusitaniae.

In yeast, external signals such as high osmolarity or oxidant conditions activate the high osmolarity glycerol (HOG) mitogen-activated protein kinase (MAPK) cascade pathway, which consists of two upstream branches, i.e. Sho1p and Sln1p and common downstream elements, including the Pbs2p MAPK kinase and the Hog1p MAPK.

Peroxisomal ABC transporters and beta-oxidation during the life cycle of the filamentous fungus Podospora anserina.

ATP-binding cassette transporters are ubiquitous proteins that facilitate transport of diverse substances across a membrane. However, their exact role remains poorly understood. In order to test their function in a fungus life cycle, we deleted the two Podospora anserina peroxisomal ABC transporter pABC1 and pABC2 genes as well as the three genes involved in peroxisomal (fox2) and mitochondrial (scdA and echA) beta-oxidation.

Insight into the role of HOG pathway components Ssk2p, Pbs2p, and Hog1p in the opportunistic yeast Candida lusitaniae.

In the present study, we have investigated the role of SSK2, PBS2, and HOG1, encoding modules of the high-osmolarity-glycerol mitogen-activated protein kinase pathway in Candida lusitaniae. Functional analysis of mutants indicated that Ssk2p, Pbs2p, and Hog1p are involved in osmotolerance, drug sensitivity, and heavy metal tolerance but not in oxidant stress adaptation.

Contributions of the response regulators Ssk1p and Skn7p in the pseudohyphal development, stress adaptation, and drug sensitivity of the opportunistic yeast Candida lusitaniae.

We recently characterized the histidine kinase receptor genes of Candida lusitaniae. For the present study, we have further investigated the role of SSK1 and SKN7, encoding response regulators. The results of functional analysis of mutants indicated that Ssk1p is involved in osmotolerance and pseudohyphal development, whereas Skn7p appears crucial for oxidative stress adaptation.

The peroxisomal import proteins PEX2, PEX5 and PEX7 are differently involved in Podospora anserina sexual cycle.

PEX5, PEX7 and PEX2 are involved in the peroxisomal matrix protein import machinery. PEX5 and PEX7 are the receptors for the proteins harbouring, respectively, a PTS1 and a PTS2 peroxisomal targeting sequence and cycle between the cytoplasm and the peroxisome. PEX2 belongs to the RING-finger complex located in the peroxisomal membrane and acts in protein import downstream of PEX5 and PEX7; it is therefore required for the import of both PTS1 and PTS2 proteins.

Comparative study of class 1 integron and Vibrio cholerae superintegron integrase activities.

Superintegrons (SIs) and multiresistant integrons (MRIs) have two main structural differences: (i) the SI platform is sedentary, while the MRI platform is commonly associated with mobile DNA elements and (ii) the recombination sites (attC) of SI gene cassette clusters are highly homogeneous, while those of MRI cassette arrays are highly variable in length and sequence. In order to determine if the latter difference was correlated with a dissimilarity in the recombination activities, we conducted a comparative study of the integron integrases of the class 1 MRI (IntI1) and the Vibrio cholerae SI (VchIntIA). We developed two assays that allowed us to independently measure the frequencies of cassette deletion and integration at the cognate attI sites.

Overexpression of a human and a fungal ABC transporter similarly suppresses the differentiation defects of a fungal peroxisomal mutant but introduces pleiotropic cellular effects.

Among the peroxisome membrane proteins, some are required for peroxisome biogenesis (e.g. PEX2) while others are not, e.