NSE5 subunit interacts with distant regions of the SMC arms in the Physcomitrium patens SMC5/6 complex.

Structural maintenance of chromosome (SMC) complexes play roles in cohesion, condensation, replication, transcription, and DNA repair. Their cores are composed of SMC proteins with a unique structure consisting of an ATPase head, long arm, and hinge. SMC complexes form long rod-like structures, which can change to ring-like and elbow-bent conformations upon binding ATP, DNA, and other regulatory factors.

Characterization of the conserved features of the NSE6 subunit of the Physcomitrium patens SMC5/6 complex.

Structural maintenance of chromosomes (SMC) complexes are molecular machines ensuring chromatin organization at higher levels. They play direct roles in cohesion, condensation, replication, transcription, and DNA repair. Their cores are composed of long-armed SMC, kleisin, and kleisin-associated subunits.

RAD51 and RAD51B Play Diverse Roles in the Repair of DNA Double Strand Breaks in .

RAD51 is involved in finding and invading homologous DNA sequences for accurate homologous recombination (HR). Its paralogs have evolved to regulate and promote RAD51 functions. The efficient gene targeting and high HR rates are unique in plants only in the moss ().

Evolution of plant telomerase RNAs: farther to the past, deeper to the roots.

The enormous sequence heterogeneity of telomerase RNA (TR) subunits has thus far complicated their characterization in a wider phylogenetic range. Our recent finding that land plant TRs are, similarly to known ciliate TRs, transcribed by RNA polymerase III and under the control of the type-3 promoter, allowed us to design a novel strategy to characterize TRs in early diverging Viridiplantae taxa, as well as in ciliates and other Diaphoretickes lineages. Starting with the characterization of the upstream sequence element of the type 3 promoter that is conserved in a number of small nuclear RNAs, and the expected minimum TR template region as search features, we identified candidate TRs in selected Diaphoretickes genomes.

Kleisin NSE4 of the SMC5/6 complex is necessary for DNA double strand break repair, but not for recovery from DNA damage in Physcomitrella (Physcomitrium patens).

Kleisin NSE4 and circular form of SMC5/6 is indispensable for DSB repair and necessary for gene targeting but is not enough for recovery of cells from DNA damage in Physcomitrella. Structural maintenance of chromosomes (SMC) complexes are involved in cohesion, condensation and maintenance of genome stability. Based on the sensitivity of mutants to genotoxic stress the SMC5/6 complex is thought to play a prominent role in DNA stabilization during repair by tethering DNA at the site of lesion by a heteroduplex of SMC5 and SMC6 encircled with non-SMC components NSE1, NSE3 and kleisin NSE4.

Roles of RAD51 and RTEL1 in telomere and rDNA stability in Physcomitrella patens.

Telomeres and ribosomal RNA genes (rDNA) are essential for cell survival and particularly sensitive to factors affecting genome stability. Here, we examine the role of RAD51 and its antagonist, RTEL1, in the moss Physcomitrella patens. In corresponding mutants, we analyse their sensitivity to DNA damage, the maintenance of telomeres and rDNA, and repair of double-stranded breaks (DSBs) induced by genotoxins with various modes of action.

Integrating plant and animal biology for the search of novel DNA damage biomarkers.

Eukaryotic genome surveillance is dependent on the multiple, highly coordinated network functions of the DNA damage response (DDR). Highlighted conserved features of DDR in plants and animals represent a challenging opportunity to develop novel interdisciplinary investigations aimed at expanding the sets of DNA damage biomarkers currently available for radiation exposure monitoring (REM) in environmental and biomedical applications. In this review, common and divergent features of the most relevant DDR players in animals and plants are described, including the intriguing example of the plant and animal kingdom-specific master regulators SOG1 (suppressor of gamma response) and p53.

Bridging Plant and Human Radiation Response and DNA Repair through an In Silico Approach.

The mechanisms of response to radiation exposure are conserved in plants and animals. The DNA damage response (DDR) pathways are the predominant molecular pathways activated upon exposure to radiation, both in plants and animals. The conserved features of DDR in plants and animals might facilitate interdisciplinary studies that cross traditional boundaries between animal and plant biology in order to expand the collection of biomarkers currently used for radiation exposure monitoring (REM) in environmental and biomedical settings.

Genotoxin induced mutagenesis in the model plant Physcomitrella patens.

The moss Physcomitrella patens is unique for the high frequency of homologous recombination, haploid state, and filamentous growth during early stages of the vegetative growth, which makes it an excellent model plant to study DNA damage responses. We used single cell gel electrophoresis (comet) assay to determine kinetics of response to Bleomycin induced DNA oxidative damage and single and double strand breaks in wild type and mutant lig4 Physcomitrella lines. Moreover, APT gene when inactivated by induced mutations was used as selectable marker to ascertain mutational background at nucleotide level by sequencing of the APT locus.

MRE11 and RAD50, but not NBS1, are essential for gene targeting in the moss Physcomitrella patens.

The moss Physcomitrella patens is unique among plant models for the high frequency with which targeted transgene insertion occurs via homologous recombination. Transgene integration is believed to utilize existing machinery for the detection and repair of DNA double-strand breaks (DSBs). We undertook targeted knockout of the Physcomitrella genes encoding components of the principal sensor of DNA DSBs, the MRN complex.