Centromere pairing enables correct segregation of meiotic chromosomes.

Proper chromosome segregation in meiosis I relies on the formation of connections between homologous chromosomes. Crossovers between homologs provide a connection that allows them to attach correctly to the meiosis I spindle. Tension is transmitted across the crossover when the partners attach to microtubules from opposing poles of the spindle.

Surprising connections between DNA binding and function for the near-complete set of yeast transcription factors.

DNA sequence-specific transcription factors (TFs) modulate transcription and chromatin architecture, acting from regulatory sites in enhancers and promoters of eukaryotic genes. How TFs locate their DNA targets and how multiple TFs cooperate to regulate individual genes is still unclear. Most yeast TFs are thought to regulate transcription via binding to upstream activating sequences, situated within a few hundred base pairs upstream of the regulated gene.

Yeast Mediator facilitates transcription initiation at most promoters via a Tail-independent mechanism.

Mediator (MED) is a conserved factor with important roles in basal and activated transcription. Here, we investigate the genome-wide roles of yeast MED by rapid depletion of its activator-binding domain (Tail) and monitoring changes in nascent transcription. Rapid Tail depletion surprisingly reduces transcription from only a small subset of genes.

Putative Cooperative ATP-DnaA Binding to Double-Stranded DnaA Box and Single-Stranded DnaA-Trio Motif upon Replication Initiation Complex Assembly.

is a region of the bacterial chromosome at which the initiator protein DnaA interacts with specific sequences, leading to DNA unwinding and the initiation of chromosome replication. The general architecture of s is universal; however, the structure of and the mode of orisome assembly differ in distantly related bacteria. In this work, we characterized of , which consists of two DnaA box clusters and a DNA unwinding element (DUE); the latter can be subdivided into a GC-rich region, a DnaA-trio and an AT-rich region.

BET family members Bdf1/2 modulate global transcription initiation and elongation in .

Human bromodomain and extra-terminal domain (BET) family members are promising targets for therapy of cancer and immunoinflammatory diseases, but their mechanisms of action and functional redundancies are poorly understood. Bdf1/2, yeast homologues of the human BET factors, were previously proposed to target transcription factor TFIID to acetylated histone H4, analogous to bromodomains that are present within the largest subunit of metazoan TFIID. We investigated the genome-wide roles of Bdf1/2 and found that their important contributions to transcription extend beyond TFIID function as transcription of many genes is more sensitive to Bdf1/2 than to TFIID depletion.

Two roles for the yeast transcription coactivator SAGA and a set of genes redundantly regulated by TFIID and SAGA.

Deletions within genes coding for subunits of the transcription coactivator SAGA caused strong genome-wide defects in transcription and SAGA-mediated chromatin modifications. In contrast, rapid SAGA depletion produced only modest transcription defects at 13% of protein-coding genes - genes that are generally more sensitive to rapid TFIID depletion. However, transcription of these 'coactivator-redundant' genes is strongly affected by rapid depletion of both factors, showing the overlapping functions of TFIID and SAGA at this gene set.

origin of chromosomal replication with two putative unwinding elements.

DNA replication is controlled mostly at the initiation step. In bacteria, replication of the chromosome starts at a single origin of replication called . The initiator protein, DnaA, binds to specific sequences (DnaA boxes) within and assembles into a filament that promotes DNA double helix opening within the DNA unwinding element (DUE).

Structure and Function of the Chromosome Replication Origin.

is the leading bacterial cause of foodborne infections worldwide. However, our understanding of its cell cycle is poor. We identified the probable origin of replication () - a key element for initiation of chromosome replication, which is also important for chromosome structure, maintenance and dynamics.

Mechanistic Differences in Transcription Initiation at TATA-Less and TATA-Containing Promoters.

A yeast system was developed that is active for transcription at both TATA-containing and TATA-less promoters. Transcription with extracts made from cells depleted of TFIID subunit Taf1 demonstrated that promoters of both classes are TFIID dependent, in agreement with recent findings. TFIID depletion can be complemented by additional recombinant TATA binding protein (TBP) at only the TATA-containing promoters.

Initiation of Chromosomal Replication in Predatory Bacterium .

is a small Gram-negative predatory bacterium that attacks other Gram-negative bacteria, including many animal, human, and plant pathogens. This bacterium exhibits a peculiar biphasic life cycle during which two different types of cells are produced: non-replicating highly motile cells (the free-living phase) and replicating cells (the intracellular-growth phase). The process of chromosomal replication in must therefore be temporally and spatially regulated to ensure that it is coordinated with cell differentiation and cell cycle progression.

Unique and Universal Features of Epsilonproteobacterial Origins of Chromosome Replication and DnaA-DnaA Box Interactions.

In bacteria, chromosome replication is initiated by the interaction of the initiator protein DnaA with a defined region of a chromosome at which DNA replication starts (). While DnaA proteins share significant homology regardless of phylogeny, regions exhibit more variable structures. The general architecture of s is universal, i.

oriC-encoded instructions for the initiation of bacterial chromosome replication.

Replication of the bacterial chromosome initiates at a single origin of replication that is called oriC. This occurs via the concerted action of numerous proteins, including DnaA, which acts as an initiator. The origin sequences vary across species, but all bacterial oriCs contain the information necessary to guide assembly of the DnaA protein complex at oriC, triggering the unwinding of DNA and the beginning of replication.

The atypical response regulator HP1021 controls formation of the Helicobacter pylori replication initiation complex.

The replication of a bacterial chromosome is initiated by the DnaA protein, which binds to the specific chromosomal region oriC and unwinds duplex DNA within the DNA-unwinding element (DUE). The initiation is tightly regulated by many factors, which control either DnaA or oriC activity and ensure that the chromosome is duplicated only when the conditions favor the survival of daughter cells. The factors controlling oriC activity often belong to the protein families of two-component systems.

Assembly of Helicobacter pylori initiation complex is determined by sequence-specific and topology-sensitive DnaA-oriC interactions.

In bacteria, chromosome replication is initiated by binding of the DnaA initiator protein to DnaA boxes located in the origin of chromosomal replication (oriC). This leads to DNA helix opening within the DNA-unwinding element. Helicobacter pylori oriC, the first bipartite origin identified in Gram-negative bacteria, contains two subregions, oriC1 and oriC2, flanking the dnaA gene.

Beyond DnaA: the role of DNA topology and DNA methylation in bacterial replication initiation.

The replication of chromosomal DNA is a fundamental event in the life cycle of every cell. The first step of replication, initiation, is controlled by multiple factors to ensure only one round of replication per cell cycle. The process of initiation has been described most thoroughly for bacteria, especially Escherichia coli, and involves many regulatory proteins that vary considerably between different species.

Helicobacter pylori oriC--the first bipartite origin of chromosome replication in Gram-negative bacteria.

Binding of the DnaA protein to oriC leads to DNA melting within the DNA unwinding element (DUE) and initiates replication of the bacterial chromosome. Helicobacter pylori oriC was previously identified as a region localized upstream of dnaA and containing a cluster of DnaA boxes bound by DnaA protein with a high affinity. However, no unwinding within the oriC sequence has been detected.

The level of AdpA directly affects expression of developmental genes in Streptomyces coelicolor.

AdpA is a key regulator of morphological differentiation in Streptomyces. In contrast to Streptomyces griseus, relatively little is known about AdpA protein functions in Streptomyces coelicolor. Here, we report for the first time the translation accumulation profile of the S.

DiaA/HobA and DnaA: a pair of proteins co-evolved to cooperate during bacterial orisome assembly.

Replication of the bacterial chromosome is initiated by binding the DnaA protein to oriC. Various factors control the ability of DnaA to bind and unwind DNA. Among them, Escherichia coli DiaA and Helicobacter pylori HobA have been characterized recently.