Biology subjects

Lv, Z.

Publications and source records attributed to Lv, Z..

4 recordsLinked to original sources

bioRxiv2018

Preliminary Study of the Potential Mechanism of CTSD in the Aging Process of Sepiella japonica: Fundamental Function Analysis

Cathepsin D, a kind of endopeptidase, can degrade peptides and proteins in lysosomes, which are involved in cell apoptosis. Previous transcriptome analysis of optic glands of Sepiella japonica across four growth stages, expression of a cathepsin D-like segment was found to be significantly different. Based on the complete cDNA sequence of S. japonica, the CTSD gene (also called sjCTSD, GenBank accession no. KY745896.1) was cloned using RACE amplification; this gene is 1389 bp in length and encodes proteins composed of 393 amino acids. Spatio-temporal expression profiles of the sjCTSD gene were determined using qPCR assays, which showed that the expression levels of sjCTSD constantly increased across four growth stages in 9 of 11 tissues that were investigated. In the optic glands, as well as pancreas and liver cells, sjCTSD expression levels sharply increased during the post-spawning phase. To investigate the potential role of the sjCTSD gene in aging progress, we constructed the prokaryotic expression vector of pET28a/sjCTSD. After induced by IPTG, the recombinant protein sjCTSD was obtained in the form of inclusion bodies, with a molecular size of approximately 40.3 kDa, the inclusion body of sjCTSD can be converted to soluble protein through the denaturation and renaturation. The results of functional experiments showed that sjCTSD could degrade bovine hemoglobin under acidic conditions, and inhibit the growth of Escherichia coli and Vibrio alginolyticus, which was speculated that the increased expression of sjCTSD may help inhibit the invasion of pathogenic bacteria with the immune function of cuttlefish declines during the aging process. To a certain extent, these results indicated the potential functional role of the sjCTSD gene in the aging process of S. japonica. This study provides insights to further understand the roles of lysosomal proteins on anti-aging effects in S. japonica and other cephalopoda species.

genetics↗

bioRxiv2018

Molecular Detection of H.pylori Antibiotic-Resistant Genes and Bioinformatics Predictive Analysis

To explore the mutation characteristics of H.pylori resistance-related genes to antibiotics of clarithromycin, levofloxacin and metronidazole. 23S rRNA, gyrA, gyrB, rdxA and frxA genes were amplified and sequenced, respectively. Their structural alteration after mutation was predicted using bioinformatics software. In the clarithromycin-resistant strains, the mutation rate in site A2143G was 74.2% (n=23). The mutations in sites C1883T, C2131T and T2179G might cause structural alteration. In the levofloxacin-resistant strains, the mutation rates in 87 (N to K/I) and 91 (D to N/Y/G) of gyrA were 28.6% (n=16) and 12.5% (n =7), respectively. Meanwhile, one of the mutation strains in site 91 was accompanied by D99N variation. Additionally, a D143E mutation was found in one drug-resistant strain. Some changes of tertiary structure occurred after these mutations. The mutation types of RdxA protein consisted of protein truncation caused by premature stop codons (n=26, 33.3%), frameshift mutations (n=8, 10.3%), FMN-binding sites (n=16, 20.5%) and the others (n=11, 14.1%). Predictive analysis showed that mutations in the first three groups and the A118S of the last group could lead to structural alteration. Our study suggested the clarithromycin-resistant sites of H.pylori were mainly located in A2143G of 23S rRNA. C1883T, C2131T and T2179G might also be related to resistance. Levofloxacin resistance was mainly based on the amino acid changes in 87 and 91 sites of gyrA. The new sites D99N and D143E might also be associated with resistance. Metronidazole resistance was related to RdxA protein truncation, frameshift, and FMN binding. The new site A118S might also be linked to drug resistance.

microbiology↗

bioRxiv2018

Phospholipid membranes promote the early stage assembly of α-synuclein aggregates

Development of Parkinsons disease is associated with spontaneous self-assembly of -synuclein (-syn). Efforts aimed at understanding this process have produced little clarity and the mechanism remains elusive. We report a novel effect of phospholipid bilayers on the catalysis of -syn aggregation from monomers. We directly visualized -syn aggregation on supported lipid bilayers using time-lapse atomic force microscopy. We discovered that -syn assemble in aggregates on bilayer surfaces even at the nanomolar concentration of monomers in solution. The efficiency of the aggregation process depends on the membrane composition, being highest for a negatively charged bilayer. Furthermore, assembled aggregates can dissociate from the surface, suggesting that on-surface aggregation can be a mechanism by which pathological aggregates are produced. Computational modeling revealed that interaction of -syn with bilayer surface changes the protein conformation and its affinity to assemble into dimers, and these properties depend on the bilayer composition. A model of the membrane-mediated aggregation triggering the assembly of neurotoxic aggregates is proposed.

neuroscience↗

bioRxiv2017

A "molecular guillotine" reveals an interphase function of Kinesin-5

Motor proteins are important for transport and force generation in a variety of cellular processes and morphogenesis. Here we design a general strategy for conditional motor mutants by inserting a protease cleavage site at the \"neck\" between the head domain and the stalk of the motor protein, making the protein susceptible to proteolytic cleavage at the neck by the corresponding protease. To demonstrate the feasibility of this approach, we inserted the cleavage site of TEV protease into the neck of the tetrameric motor Kinesin-5. Application of TEV protease led to a specific depletion and functional loss of Kinesin-5 in Drosophila embryos. By this, we revealed that Kinesin-5 stabilized the microtubule network during interphase in syncytial embryos. The \"molecular guillotine\" can potentially be applied to many motor proteins due to the conserved structures of kinesin, dynein and myosin with accessible necks.\n\nAuthor summaryWe design a general strategy for conditional motor mutants by inserting a protease cleavage site between head and stalk domain of the motor protein, making it susceptible to specific proteolytic cleavage. We demonstrate the feasibility of the approach with the motor Kinesin-5 and the protease TEV in Drosophila embryos. This approach can potentially be applied to motor proteins kinesin, dynein and myosin due to the conserved structures.

developmental biology↗