ABSTRACT
Protein lysine methylation is a prevalent post-translational modification (PTM) and plays critical roles in all domains of life. However, its extent and function in photosynthetic organisms are still largely unknown. Cyanobacteria are a large group of prokaryotes that carry out oxygenic photosynthesis and are applied extensively in studies of photosynthetic mechanisms and environmental adaptation. Here we integrated propionylation of monomethylated proteins, enrichment of the modified peptides, and mass spectrometry (MS) analysis to identify monomethylated proteins in Synechocystis sp. PCC 6803 (Synechocystis). Overall, we identified 376 monomethylation sites in 270 proteins, with numerous monomethylated proteins participating in photosynthesis and carbon metabolism. We subsequently demonstrated that CpcM, a previously identified asparagine methyltransferase in Synechocystis, could catalyze lysine monomethylation of the potential aspartate aminotransferase Sll0480 both in vivo and in vitro and regulate the enzyme activity of Sll0480. The loss of CpcM led to decreases in the maximum quantum yield in primary photosystem II (PSII) and the efficiency of energy transfer during the photosynthetic reaction in Synechocystis. We report the first lysine monomethylome in a photosynthetic organism and present a critical database for functional analyses of monomethylation in cyanobacteria. The large number of monomethylated proteins and the identification of CpcM as the lysine methyltransferase in cyanobacteria suggest that reversible methylation may influence the metabolic process and photosynthesis in both cyanobacteria and plants.
Subject(s)
Bacterial Proteins/metabolism , Lysine/metabolism , Methyltransferases/metabolism , Photosynthesis , Protein Processing, Post-Translational , Synechocystis/growth & developmentABSTRACT
BACKGROUND:The main treatment of lumbar isthmic spondylolisthesis is the surgery, in a broader attempt to decompression, reduction, fixation and fusion of the lesioned segments. The golden standard of the treatment is biological fusion, while internal fixation is a reliable assistance for fusion therapy. ＜br> OBJECTIVE:To discuss the clinical value and curative effect of intervertebral fusion cage combined with pedicle screw systems for the treatment of lumbar isthmic spondylolisthesis. ＜br> METHODS:From March 2010 to March 2013, 21 cases of isthmic spondylolisthesis were treated with intervertebral fusion cage combined with pedicle screw systems, including 18 cases of spondylolisthesis of degree II and 3 cases of spondylolisthesis of degree III. Al patients were fol owed up regularly, taking JOA lumbago score and visual analog scale score as the objective evaluation criteria of pain in postoperative fol ow-ups. The curative effect was assessed by Macrab standard, and the functional recovery was evaluated based on indicators such as Prolo, and the spinal fusion rate was assessed according to Lenke criteria. Changes of slippage rate, slippage angle, sacral inclination angle and intervertebral space post height in preoperative and postoperative periods were evaluated by iconography data. ＜br> RESULTS AND CONCLUSION:Al the 21 patients with isthmic spondylolisthesis were fol owed up for 12-16 months. JOA lumbago score and vasual analog scale score of al patients were improved after treatment, and the difference was statistical y significant compared with before treatment (P=0.000). According to Macrab evaluation criteria, there were 17 excellent cases and 4 good cases. Each indicator evaluated by preoperative Prolo activities and symptom grading showed significant differences in preoperative and postoperative periods (P=0.003). Postoperative lumbar spondylolisthesis was basical y reset, the slippage angle was significantly reduced, the sacral inclination angle was increased, and the height of the intervertebral space was recovered basical y. Intervertebral fusion cage combined with pedicle screw systems was one of the effective strategies to treat lumbar isthmic spondylolisthesis.
ABSTRACT
BACKGROUND:Telomerase reverse transcriptase (TERT) plays an important role in telomerase activation, however there is rare report addressing the construction of the lentivirus targeted its genes to inhibit its expression in the spinal cord astrocytes. OBJECTIVE:To construct recombinant lentivirus vector expressing smal interfering RNA against TERT gene and to evaluate its potential for inhibiting the TERT expression. METHODS:After shRNA-TERT sequence was designed and synthesized, the sequence was amplified by PCR and then connected to plasmid pLentilox3.7U6-hTERT to construct recombinant plasmid. The recombinant plasmid was then transfected to DH5αcel s to screen positive colony, and the sequence was identified. The recombinant plasmid pLentilox3.7U6-TERT was transfected in 293T cel s, generating recombinant lentivirus Le-TERT. The titer of recombinant lentivirus was determined and Le-TERT was transfected into the rat spinal cord astrocytes. The expression of TERT in astrocytes was detected by RT-PCR, western blot and immunofluorescence assay. RESULTS AND CONCLUSION:The gene sequencing analysis confirmed that, recombinant plasmid pLentilox3.7U6-TERT was successful y constructed. The real-time quantitative PCR, western blot analysis and immunofluorescence assay indicated that, after Le-TERT was transfected in the astrocytes for 4 days, the inhibition rate of TERT mRNA was (63.98±2.6)%, and Le-TERT was lowly expressed in the transfected astrocytes. Recombinant expression vector pLentilox3.7U6-TERT can produce the lentivirus at high titer and effectively inhibit TERT expression in the transfected astrocytes.
ABSTRACT
BACKGROUND:Telomerase reverse transcriptase (TERT) plays an important role in telomerase activation. OBJECTIVE:To construct the targeting short hairpin RNA plasmid vector expressing TERT gene from astrocytes by using pLentilox3.7.U6. METHODS:By using two sequences from TERT gene, we synthetized sense and antisense strand template sequences of RNA interference molecular in vitro, and then obtained the complementary strands through annealing procedure. We connected the strands with pLentilox3.7.U6 that was sequenced and transfected into the Escherichia coli. In the end, we tested its effect of reducing the TERT gene expressing by using cultured astrocytes from rat spinal cord in vitro through western blot and immunofluorescence technique. RESULTS AND CONCLUSION:Western blot and immunofluorescence assay showed that, compared with the control group, the interference groups had a lower TERT expression in astrocytes. The targeting short hairpin RNA plasmid vector expressing TERT gene is useful to reduce the TERT gene expression. The targeting short hairpin RNA plasmid vector expressing TERT gene is valid for us to do the further test learning the mechanism of astrocytes in spinal cord injury.
ABSTRACT
Objective To investigate the relationship between telomerase reverse transcriptase (TERT) gene expression and astrocyte activation.Methods Twenty neonatal 3-day-old male SD rats were used for culture of the astrocytes.The astrocytes were divided into Group A (activated,non-transfected astrocytes),Group B (activated,transfected astrocytes),Group C (unactivated astrocytes) and Group D (activated,empty plasmid transfected astrocytes) according to the random number table,with 5 rats per group.The cell proliferation rate in each group was detected by cell counting kit-8 (CCK-8) ;TERT expression by immunocytochemical method; expressions of TERT and glial fibrillary acidic protein (GFAP) genes by RT-PCR assay.Results Astrocytic proliferation ability in Group B lowered significantly as compared with that in Groups A,D and C (F =43.418,P ＜ 0.01).Expressions of TERT and GFAP mRNAs in Groups A and D were significantly higher than those in Group B and C,and no significant difference was found between Groups A and D.Besides,there was a linear correlation between mRNAs expressions of both genes in Groups A and D (r =0.701,0.704,P ＜ 0.01),while no significant linear correlation was observed in Groups B and C (r =0.260,P ＞ 0.05).Expressions of TERT and GFAP proteins in Groups A and D were markedly higher than those in Groups B and C and no significant difference was found between Groups A and D.Conclusion TERT genes are involved in the activation of astrocytes and exert effect on promoting the activation of astrocytes.