Dyella monticola sp. nov. and Dyella psychrodurans sp. nov., isolated from monsoon evergreen broad-leaved forest soil of Dinghu Mountain, China.

Cells of bacterial strains 4 G-K06T and 4MSK11T, isolated from soil samples collected from monsoon evergreen broad-leaved forest of the Dinghushan Mountain (112° 31' E 23° 10' N), Guangdong Province, PR China, were Gram-stain-negative, aerobic, non-spore-forming, non-motile and rod-shaped. Strain 4 G-K06T grew at 10-37 °C, pH 3.5-7.5 and 0-3.5 % (w/v) NaCl; while 4MSK11T grew at 4-42 °C, pH 3.5-7.5 and 0-2.5 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed strain 4 G-K06T formed a clade with Dyellaflagellata 4 M-K16T, Dyella acidisoli 4M-Z03T, Dyellahumi DHG40T and Dyellanitratireducens DHG59T, while strain 4MSK11T formed a clade with Dyellacaseinilytica DHOB09T and Dyellamobilis DHON07T, both within the genus Dyella. The result of the partial atpD, gyrB and lepA gene sequence analysis supported the conclusion based on 16S rRNA gene sequence analysis, which showed that these two strains represent two novel species of Dyella. The average nucleotide identity and digital DNA-DNA hybridization value for the whole genomes were 75.0-79.0 and 20.3-22.6 % between strains 4 G-K06T, 4MSK11T and those described Dyella species with genome sequences; while the DNA-DNA hybridization rates between strains 4 G-K06T, 4MSK11T and closely related Dyella species (without genome sequence) were 29.5-41.8 %. The major cellular fatty acids of these two strains were iso-C15 : 0, iso-C16 : 0 and iso-C17 : 1ω9c, while the major polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and several unidentified phospholipids and aminophospholipids. The only ubiquinone of these two strains was ubiquinone-8. The DNA G+C contents of 4 G-K06T and 4MSK11T were 60.4 and 61.3 mol%, respectively. On the basis of the evidence presented here, strains 4 G-K06T and 4MSK11T represent two novel species of the genus Dyella, for which the names Dyella monticola sp. nov. (type strain 4 G-K06T=LMG 30268T=GDMCC 1.1188T) and Dyella psychrodurans sp. nov. (type strain 4MSK11T=KCTC 62280T=GDMCC 1.1185T) are proposed.

Transmembrane nuclease NUMEN/ENDOD1 regulates DNA repair pathway choice at the nuclear periphery.

Proper repair of DNA damage lesions is essential to maintaining genome integrity and preventing the development of human diseases, including cancer. Increasing evidence suggests the importance of the nuclear envelope in the spatial regulation of DNA repair, although the mechanisms of such regulatory processes remain poorly defined. Through a genome-wide synthetic viability screen for PARP-inhibitor resistance using an inducible CRISPR-Cas9 platform and BRCA1-deficient breast cancer cells, we identified a transmembrane nuclease (renamed NUMEN) that could facilitate compartmentalized and non-homologous end joining-dependent repair of double-stranded DNA breaks at the nuclear periphery. Collectively, our data demonstrate that NUMEN generates short 5' overhangs through its endonuclease and 3'→5' exonuclease activities, promotes the repair of DNA lesions-including heterochromatic lamina-associated domain breaks as well as deprotected telomeres-and functions as a downstream effector of DNA-dependent protein kinase catalytic subunit. These findings underline the role of NUMEN as a key player in DNA repair pathway choice and genome-stability maintenance, and have implications for ongoing research into the development and treatment of genome instability disorders.