Developmentally Programmed Switches in DNA Replication: Gene Amplification and Genome-Wide Endoreplication in .

Locus-specific gene amplification and genome-wide endoreplication generate the elevated copy number of ribosomal DNA (rDNA, 9000 C) and non-rDNA (90 C) chromosomes in the developing macronucleus of . Subsequently, all macronuclear chromosomes replicate once per cell cycle during vegetative growth. Here, we describe an unanticipated, programmed switch in the regulation of replication initiation in the rDNA minichromosome.

A germline-limited piggyBac transposase gene is required for precise excision in Tetrahymena genome rearrangement.

Developmentally programmed genome rearrangement accompanies differentiation of the silent germline micronucleus into the transcriptionally active somatic macronucleus in the ciliated protozoan Tetrahymena thermophila. Internal eliminated sequences (IES) are excised, followed by rejoining of MAC-destined sequences, while fragmentation occurs at conserved chromosome breakage sequences, generating macronuclear chromosomes. Some macronuclear chromosomes, referred to as non-maintained chromosomes (NMC), are lost soon after differentiation.

Proximity Interactions among Basal Body Components in Trypanosoma brucei Identify Novel Regulators of Basal Body Biogenesis and Inheritance.

Unlabelled: The basal body shares similar architecture with centrioles in animals and is involved in nucleating flagellar axonemal microtubules in flagellated eukaryotes. The early-branching Trypanosoma brucei possesses a motile flagellum nucleated from the basal body that consists of a mature basal body and an adjacent pro-basal body. Little is known about the basal body proteome and its roles in basal body biogenesis and flagellar axoneme assembly in T.

Impact of salinity-tolerant MCM6 transgenic tobacco on soil enzymatic activities and the functional diversity of rhizosphere microbial communities.

The development of genetically modified plants for agriculture has provided numerous economic benefits, but has also raised concern over the potential impact of transgenic plants upon the environment. The rhizosphere is the soil compartment that is directly under the influence of living roots; it constitutes a complex niche likely to be exploited by a wide variety of bacteria potentially influenced by the introduction of transgenes in genetically modified plants. In the present study, the impact of overexpression of the salinity stress-tolerant minichromosome maintenance complex subunit 6 (MCM6) gene upon functional diversity and soil enzymatic activity in the rhizosphere of transgenic tobacco in the presence and absence of salt stress was examined.

Plant MCM proteins: role in DNA replication and beyond.

Mini-chromosome maintenance (MCM) proteins form heterohexameric complex (MCM2-7) to serve as licensing factor for DNA replication to make sure that genomic DNA is replicated completely and accurately once during S phase in a single cell cycle. MCMs were initially identified in yeast for their role in plasmid replication or cell cycle progression. Each of six MCM contains highly conserved sequence called "MCM box", which contains two ATPase consensus Walker A and Walker B motifs.

The Cdc45·Mcm2-7·GINS protein complex in trypanosomes regulates DNA replication and interacts with two Orc1-like proteins in the origin recognition complex.

Accurate DNA replication requires a complex interplay of many regulatory proteins at replication origins. The CMG (Cdc45·Mcm2-7·GINS) complex, which is composed of Cdc45, Mcm2-7, and the GINS (Go-Ichi-Ni-San) complex consisting of Sld5 and Psf1 to Psf3, is recruited by Cdc6 and Cdt1 onto origins bound by the heterohexameric origin recognition complex (ORC) and functions as a replicative helicase. Trypanosoma brucei, an early branched microbial eukaryote, appears to express an archaea-like ORC consisting of a single Orc1/Cdc6-like protein.

Promoter of a salinity and cold stress-induced MCM6 DNA helicase from pea.

The eukaryotic hetrohexameric mini-chromosome maintenance (MCM2-7) proteins complex provides DNA unwinding function during the DNA replication. The complex also functions as DNA replication licensing factor which ensures that the DNA in genome is replicated only once per cell division cycle. Recently, a single subunit MCM6 from pea has been shown to contain helicase and ATPase activities in vitro.

A single subunit MCM6 from pea promotes salinity stress tolerance without affecting yield.

The eukaryotic pre-replicative complex (Pre-RC), including heterohexameric minichromosome maintenance (MCM2-7) proteins, ensures that the DNA in genome is replicated only once per cell division cycle. The MCMs provide DNA unwinding function during the DNA replication. Since MCM proteins play essential role in cell division and most likely are affected during stress conditions therefore their overexpression in plants may help in stress tolerance.

A single subunit MCM6 from pea forms homohexamer and functions as DNA helicase.

The initiation of DNA replication starts from origins and is controlled by a multiprotein complex, which involves about twenty protein factors. One of the important factors is hetrohexameric minichromosome maintenance (MCM2-7) protein complex which is evolutionary conserved and functions as essential replicative helicase for DNA replication. Here we report the isolation and characterization of a single subunit of pea MCM protein complex, the MCM6.

Pea lectin receptor-like kinase promotes high salinity stress tolerance in bacteria and expresses in response to stress in planta.

The plant lectin receptor-like kinases (LecRLKs) are involved in various signaling pathways but their role in salinity stress tolerance has not heretofore been well described. Salinity stress negatively affects plant growth/productivity and threatens food security worldwide. Based on functional gene-mining assay, we have isolated 34 salinity tolerant genes out of one million Escherichia coli (SOLR) transformants containing pea cDNAs grown in 0.

Isolation of high salinity stress tolerant genes from Pisum sativum by random overexpression in Escherichia coli and their functional validation.

Salinity stress is one of the major factors which reduce crop plants growth and productivity resulting in significant economic losses worldwide. Therefore, it would be fruitful to isolate and functionally identify new salinity stress-induced genes for understanding the mechanism and developing salinity stress tolerant plants. Based on functional gene screening assay, we have isolated few salinity tolerant genes out of one million Escherichia coli (SOLR) transformants containing pea cDNAs.