Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bacterial two-hybrid system is a newly developed method for studying protein-protein interactions, especially for effects of the environmental factors on the interaction. In our studies of the effect of NH(4)( ) or oxygen on the NifL-NifA interaction, it was found that E.coli strain DHP1 cya(-), when transformed by T18-NifL together with T25-NifA, exhibited high activity of beta-galactosidase in the presence of NH(4)( ), and appeared as red colonies when grown in MacConkey/maltose agar. This indicated the direct interaction of NifL and NifA. However,similar phenomena were also shown in the case of the DHP1 cya(-) strain harboring T18-NifL or T25-NifL alone, respectively, without its interacting counterpart T25-NifA or T18-NifA. In this paper, a brief method is presented to detect the protein-protein interaction using direct assay of the adenylate cyclase, thus minimizing the false positives produced by the beta-galactosidase activity assay or MacConkey/maltose agar plating.
Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai) 2001
PMID:Improvement of Bacterial Two Hybrid System. 1205 Jul 95

The lacZ gene which codes for beta-galactosidase from E.coli does not work in Candida albicans. In this work a reporter system with Kl LAC4 gene was contructed, coding for beta-galactosidase from Kluyveromyces lactis. Kl LAC4 gene was fused to the promoter of ADH1 of Candida albicans with the terminator sequence of ADH1 at the tail. The constructed plasmid, named pYPB1-LAC4, was used to transform Candida albicans. beta-galactosidase activity was measured by plate assay, when cultured on solid medium, and by photometric assay, when cultured in liquid medium. The results suggest that LAC4 of Kluyveromyces lactis can serve as a reporter gene in Candida albicans.
Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai) 2000
PMID:Using Kl LAC4 as a Reporter Gene in Candida albicans. 1205 2

In order to efficiently recover recombinant proteins, a temperature-sensitive lytic system was constructed on the basis of the feature that T4 lysozyme disrupts the bacteria through cutting specific bond in the peptidoglycan layer of cell wall. This system was evaluated by constructing and introducing a low copy plasmid pSC-lys (pSC101 replication origin) into E.coli. The plasmid contained a temperature sensitive T4 lysozyme (LYS(ts)) gene under the control of three tandem tac promoters and the LacI repressor, which is compatible with other plasmids carrying pMB1, ColE1 replication origins, etc. Under the optimum lysis conditions, 2--5 fold condensed cultures resuspended in buffer A, beta-galactosidase, recombinant chaperone GroEL and ZZ-fusion salmon hexamic calcitonin (Cal6) in E.coli were released simply, rapidly, and quantitatively, as co-expressed with LYS(ts). The two tested recombinant proteins maintained their significant productions. Instead of other cumbersome lysising methods, this novel lytic system will be useful in recovery of recombinant proteins for further purification in the field of biotechnology.
Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai) 2000
PMID:The Application of a Novel Lytic System to the Recovery of Recombinant Proteins in E.coli. 1207 42

The level of p21 mRNA and protein in cultured human umbilical arterial vascular smooth muscle cells were assayed by immunochemical staining and RT-PCR. The expression and phosphorylation status of Rb protein were examined by Western blot. It was observed that the senescent vascular smooth muscle cells exerted morphological changes with transmission electron microscope and characterized with beta-galactosidase staining. The flow cytometry was used for cell cycle analysis. Introduction of exogenous Rb gene could induce the expression of p21 gene leading to inhibition of phosphorylation of Rb protein. The senescent vascular smooth muscle cells at G0/G1 phase of the cell cycle were found following transfection of Rb gene recombinant adenovirus. These results show that exogenous Rb gene regulate cell cycle progression and promote cell senescence by induction of p21 gene expression.
Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai) 1999
PMID:Effect of Exogenous Rb Gene on Expression of p21 Gene in Vascular Smooth Muscle Cells. 1213 9

The translation initiation rate is greatly affected by the secondary structure of the translation initiation region (TIR) of mRNA. A novel system was established for improving the translation initiation rate of a foreign gene in E. coli. As a model, the 5' 114 bp coding sequence (38 amino acids from the start codon) of human proliferating cell nuclear antigen (PCNA) gene was fused with the lacZ' gene at its 5' end in vector pTZ19R. A Shine/Dalgarno (SD) sequence GAGGT was inserted to the -8 position of AUG by site-directed mutation. Then the flanking sequences of SD, which were the 6 nucleotides upstream the SD and the 7 nucleotides between SD and AUG, were randomly changed by PCR using a synthetic primer with partially random sequences. This random mutation led to potential variations in the secondary structure of the TIR of mRNA through base pairing with the 5' coding sequence. The 5' PCNA-LacZ' mRNA could be efficiently and specifically transcribed by inducible T7 RNA polymerase in E. coli strain JM 109 (DE3). There were 269 clones of 5' PCNA-LacZ' fusion plasmid selected first by the blue color on X-gal plate and then by hybridization with a 5' PCNA probe. Eight clones with different blue colors among the 269 clones were chosen for beta-galactosidase activity assay. The results showed that the difference between their enzyme activities was more than 20 fold, but there seemed no apparent difference at the transcription level as assayed by RNA dot hybridization, which suggested that the difference in the expression of the fusion protein was due to the different rate of translation initiation. Thus, by this strategy, an effective translation initiation region for the high expression of human PCNA gene in E. coli was obtained.
Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai) 1998
PMID:A New Strategy for Optimizing the Translation Initiation Rate of Foreign Gene Expression in E. coli. 1216 85

The Small Cell lung Carcinoma cell line NCI-H128 cDNA library constructed in Lambda gtll was screened by tumor associated antigen specific monoclonal antibody 2F7. The No.4 positive clone was further investigated. The lysogen of the No.4 clone could be induced at 42 degrees to produce 165 kD fusion protein by IPTG. This fusion protein can be detected by both the monoclonal antibody 2F7 and the anti-beta-galactosidase monoclonal antibody. Antigen Competitive Assay showed that the fusion protein purified by PAGE could compete with the natural tumor associated antigen on the membrane and combine with the monoclonal antibody 2F7. PCR reaction showed the inserted DNA fragment of No.4 Clone to be about 1.3 kb. The DNA inserted fragment was sub-cloned into the plasmid vector Bluescript-sk. Northern blot showed that it was specific for H128 cell line. These results showed that the gene of the tumor associated antigen which specifically reacted with the monoclonal antibody 2F7 was cloned.
Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai) 1996
PMID:Cloning of a Tumor Antigen-related Gene in Small Cell Lung Carcinoma. 1223 4

The vector pIRK was constructed by using a 2.2 kb EcoRI fragment of rDNA from Kluyveromyces lactis for targeted homologous recombination, with the URA3 gene from Saccharomyces cerevisiae acting as a selection marker. By the examination of the copy number, stability and chromosomal location of the vector in K. lactis transformants the results demonstrated that: (1) of the different transformants, the average copy number of the plasmid pIRK was 120 per cell; (2) after 50 generations of growth in rich medium, the vector displayed high stability. (3) all integration events occurred in the chromosome IV where genomic rDNA located. Using this vector, the LAC4 gene cloned from K. fragilis was expressed. The yield of beta-galactosidase related directly to the vector's copy number. The highest activity of beta-galactosidase produced by transformants was 8.6 times higher than that produced by the wild type strain of K. fragilis under the same conditions.
Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai) 1996
PMID:The Construction and Application of the Multi-copy Integration Vector in K. lactis. 1223 16