The Altered Functions of Shelterin Components in ALT Cells.

Telomeres are nucleoprotein complexes that cap the ends of eukaryotic linear chromosomes. Telomeric DNA is bound by shelterin protein complex to prevent telomeric chromosome ends from being recognized as damaged sites for abnormal repair. To overcome the end replication problem, cancer cells mostly preserve their telomeres by reactivating telomerase, but a minority (10-15%) of cancer cells use a homologous recombination-based pathway called alternative lengthening of telomeres (ALT). Recent studies have found that shelterin components play an important role in the ALT mechanism. The binding of TRF1, TRF2, and RAP1 to telomeres attenuates ALT activation, while the maintenance of ALT telomere requires TRF1 and TRF2. POT1 and TPP1 can also influence the occurrence of ALT. The elucidation of how shelterin regulates the initiation of ALT remains elusive. This review presents a comprehensive overview of the current findings on the regulation of ALT by shelterin components, aiming to enhance the insight into the altered functions of shelterin components in ALT cells and to identify potential targets for the treatment of ALT tumor cells.

Distinct Expression of the Two NO-Forming Nitrite Reductases in Thermus antranikianii DSM 12462T Improved Environmental Adaptability.

Hot spring ecosystems are analogous to some thermal environments on the early Earth and represent ideal models to understand life forms and element cycling on the early Earth. Denitrification, an important component of biogeochemical nitrogen cycle, is highly active in hot springs. Nitrite (NO2-) reduction to nitric oxide (NO) is the significant and rate-limiting pathway in denitrification and is catalyzed by two types of nitrite reductases, encoded by nirS and nirK genes. NirS and NirK were originally considered incompatible in most denitrifying organisms, although a few strains have been reported to possess both genes. Herein, we report the functional division of nirS and nirK in Thermus, a thermophilic genus widespread in thermal ecosystems. Transcriptional levels of nirS and nirK coexisting in Thermus antranikianii DSM 12462T were measured to assess the effects of nitrite, oxygen, and stimulation time. Thirty-nine Thermus strains were used to analyze the phylogeny and distribution of nirS and nirK; six representative strains were used to assess the denitrification phenotype. The results showed that both genes were actively transcribed and expressed independently in T. antranikianii DSM 12462T. Strains with both nirS and nirK had a wider range of nitrite adaptation and revealed nir-related physiological adaptations in Thermus: nirK facilitated adaptation to rapid changes and extended the adaptation range of nitrite under oxygen-limited conditions, while nirS expression was higher under oxic and relatively stable conditions.

A novel thermal Cas12b from a hot spring bacterium with high target mismatch tolerance and robust DNA cleavage efficiency.

Clustered regularly interspaced short palindromic repeats (CRISPR)-associated proteins (Cas), such as Cas9 and Cpf1, are RNA-guided endonucleases that target and degrade nucleic acids, providing powerful genomic editing and molecular diagnostic tools. Cas12b enzymes are distinct effectors; however, their features and catalytic boundaries require further characterization. We identified BrCas12b from the thermophile bacterium Brevibacillus sp. SYSU G02855 as a novel ortholog of cas12b. Biochemical analyses revealed that BrCas12b is a dual-RNA-guided endonuclease with higher optimum reaction temperature than that of other reported members of Cas12b. The seed sequence of BrCas12b is only 4 nt in length, indicating that it has greater target mismatch tolerance than that of previously reported Cas effectors; however, it contains a compensatory effect at the position of the cleavage site. Using fluorescence-based detection method to evaluate target cleavage efficiency, we showed that BrCas12b has robust enzymatic cleavage activity (Kcat/Km (s-1 M-1) = 8.80 × 1011), which is significantly higher than that of AacCas12b (Kcat/Km (s-1 M-1) = 7.56 × 108) from Alicyclobacillus acidoterrestris. The results increase our understanding of the catalytic mechanism of Cas12b family members and suggest that BrCas12b might be useful in the application of genomic editing and molecular diagnosis.

Comparative genomics analysis of Nitriliruptoria reveals the genomic differences and salt adaptation strategies.

The group Nitriliruptoria, recently classified as a separate class of phylum Actinobacteria, has five members at present, which belong to halophilic or halotolerant Actinobacteria. Here, we sequenced the genomes of Egicoccus halophilus EGI 80432T and Egibacter rhizosphaerae EGI 80759T, and performed a comparative genomics approach to analyze the genomic differences and salt adaptation mechanisms in Nitriliruptoria. Phylogenetic analysis suggested that Euzebya tangerina F10T has a closer phylogenetic relationship to Euzebya rosea DSW09T, while genomic analysis revealed highest genomic similarity with Nitriliruptor alkaliphilus ANL-iso2T and E. halophilus EGI 80432T. Genomic differences of Nitriliruptoria were mainly observed in genome size, gene contents, and the amounts of gene in per functional categories. Furthermore, our analysis also revealed that Nitriliruptoria possess similar synthesis systems of solutes, such as trehalose, glutamine, glutamate, and proline. On the other hand, each member of Nitriliruptoria species possesses specific mechanisms, K+ influx and efflux, betaine and ectoine synthesis, and compatible solutes transport to survive in various high-salt environments.

Bacillus camelliae sp. nov., isolated from Pu'er tea.

A novel aerobic, Gram-stain-positive, sporogenous, rod-shaped bacterial strain, 7578-1T, was isolated from ripened Pu'er tea. Based on 16S rRNA gene sequence similarity comparisons, strain 7578-1T was grouped into the genus Bacillus and appeared to be closely related to the type strains Bacillus shackletoniiLMG 18435T (98.4 %), Bacillus acidicolaDSM 14745T (97.6 %), Bacillus paralicheniformis KACC 18426T (97.2 %) and Bacillus ginsengihumi KCTC 13944T (96.7 %). The fatty acid profile containing the major fatty acids, iso-C15 : 0, anteiso-C15 : 0 and anteiso-C17 : 0 supported the allocation of strain 7578-1T to the genus Bacillus. The strain had a cell-wall type A1γ peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. The major menaquinone was MK-7 (95 %). The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, one unidentified phospholipid and one unidentified lipid. The average nucleotide identity values between strain 7578-1T and its most closely related species were 67.8-82.4 % by OrthoANIu analysis. The DNA-DNA relatedness value between strain 7578-1T and the type strains of closely related species were 17-39 %, again indicating that strain 7578-1T represented a novel species in the genus Bacillus. The DNA G+C content of strain 7578-1T was 36.0 mol%. On the basis of the presented polyphasic evidence, strain 7578-1T is considered to represent a novel species of the genus Bacillus, for which we propose the name Bacillus camelliae sp. nov. The type strain is 7578-1T (=CGMCC 1.15374T=KCTC 33845T).

Pullulanibacillus camelliae sp. nov., isolated from Pu'er tea.

A novel Gram-stain-positive, strictly aerobic, endospore-forming, rod-shaped bacterial strain 7578-24T was isolated from ripened Pu'er tea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 7578-24T clustered with species of the genus Pullulanibacillus in the family Sporolactobacillaceae with 97.8-95.2 % sequence similarities, and was most closely related to Pullulanibacillus pueri YN3T with 97.8 % 16S rRNA gene sequence similarity. The DNA-DNA relatedness value between strain 7578-24T and P. pueri YN3T was 35 %. Strain 7578-24T had a cell-wall type A1γ peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. The major menaquinone was menaquinone 7 (MK-7). C18 : 1ω7c (45.4 %), anteiso-C17 : 0 (30.6 %) and anteiso-C15 : 0 (10.1 %) were the predominant fatty acids, and diphosphatidylglycerol, phosphatidylglycerol, five unknown phospholipids and one unknown aminolipid were the major polar lipids. The DNA G+C content of strain 7578-24T was 45.2 mol%. Strain 7578-24T could be differentiated from other related species of the genus Pullulanibacillus based on phenotypic characteristics, chemotaxonomic differences, phylogenetic analysis and DNA-DNA hybridization data. On the basis of polyphasic evidence from this study, a novel species of the genus Pullulanibacillus named Pullulanibacillus camelliae sp. nov. is proposed, with strain 7578-24T (=CGMCC 1.15371T=JCM 31236T) as the type strain.

Aeromicrobium camelliae sp. nov., isolated from Pu'er tea.

A novel Gram-reaction-positive, aerobic and non-spore-forming rod-shaped bacterial strain, YS17T, was isolated from ripened Pu'er tea. Growth of the strain was observed at 15-50 °C (optimum 30-37 °C) and at pH 5.5-10.5 (optimum 6.0-9.5). Phylogenetic analysis of 16S rRNA gene sequences indicated that the strain represented a member of the genus Aeromicrobium. The strains most closely related to YS17T were Aeromicrobium erythreum DSM 8599T, Aeromicrobium alkaliterrae JCM 13518T and Aeromicrobium ginsengisoli JCM 14732T, with 16S rRNA gene sequence similarities of 96.8, 96.8 and 96.7 %, respectively. DNA-DNA hybridization of YS17T with the type strains of the most closely related species, A. erythreum DSM 8599T, A. alkaliterrae JCM 13518T and A. ginsengisoli JCM 14732T, yielded reassociation values of 10.9, 16.8 and 10.9 %, respectively. The diagnostic diamino acid of the cell wall peptidoglycan was ll-diaminopimelic acid. The predominant menaquinones were menaquinone MK-9(H4) (76 %) and MK-8(H4) (17 %). The major fatty acids were C16 : 0, 10-methyl C18 : 0 and C18 : 1ω9c. The DNA G+C content of YS17T was 66 mol%. YS17T could be differentiated from recognized species of the genus Aeromicrobium on the basis of phenotypic characteristics, chemotaxonomic differences, phylogenetic analysis and DNA-DNA hybridization data. On the basis of evidence from the polyphasic analyses performed as part of this study a novel species, Aeromicrobium camelliae sp. nov., is proposed, with strain YS17T ( = CGMCC 1.12942T = JCM 30952T) as the type strain.

Pullulanibacillus pueri sp. nov., isolated from Pu'er tea.

A novel Gram-stain-positive, aerobic, endospore-forming, rod-shaped bacterial strain YN3(T) was isolated from ripened Pu'er tea. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain belonged to the family Sporolactobacillaceae and was closely related to Pullulanibacillus naganoensis DSM 10191(T) (95.8% 16S rRNA gene sequence similarity) and Pullulanibacillus uraniitolerans DSM 19429(T) (95.4%). Growth of the strain was observed at 20-50 °C (optimum 30-37 °C), at pH 4.0-8.0 (optimum pH 5.0-6.0). The strain had a cell-wall type A1γ peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinone was menaquinone-7 (MK-7). The major fatty acids were anteiso-C15:0, anteiso-C17:0 and C18:1ω7c. The DNA G+C content of strain YN3(T) was 38.7 mol%. Strain YN3(T) could be differentiated from recognized species of the genus Pullulanibacillus based on phenotypic characteristics, chemotaxonomic differences, phylogenetic analysis and DNA-DNA hybridization data. On the basis of polyphasic evidence from this study, Pullulanibacilluspueri sp. nov., is proposed, with strain YN3(T) ( = CGMCC 1.12777(T ) = JCM 30075(T)) as the type strain.