Cloning of mini-mu bacteriophage in cosmids: in vivo packaging into phage lambda heads

Long non-coding RNA VPS9D1-AS1 promotes growth of colon adenocarcinoma by sponging miR-1301-3p and CLDN1

Colon adenocarcinoma is a frequent malignancy among all colon cancer types. Long non-coding RNAs (lncRNAs) are involved in the progression of colon adenocarcinoma. This study aimed to uncover the molecular mechanism of VPS9D1-AS1 in regulating colon adenocarcinoma development. Quantitative reverse transcription-polymerase chain reaction (RT-qPCR) revealed that VPS9D1-AS1 expression was markedly upregulated in colon adenocarcinoma tissues and cell lines. Cell functional experiments showed that knockdown of VPS9D1-AS1 repressed the growth and invasion of colon adenocarcinoma cells but upregulated cell apoptosis. In addition, we confirmed the interaction of VPS9D1-AS1-miR-1301-3p-CLDN1 using a luciferase assay. Downregulation of miR-1301-3p promoted the progression of colon adenocarcinoma cells. In conclusion, VPS9D1-AS1 facilitated cell growth and suppressed apoptosis of colon adenocarcinoma cells by sponging miR-1301-3p and upregulating CLDN1, which may be effective therapeutic strategies for patients with colon adenocarcinoma.

Isolation and nucleotide sequence of the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase gene from Acetobacter xylinum

A genetic locus from Acetobacter xylinum involved in acetan polysaccharide synthesis has been characterized. The chromosomal region was identified by screening a genomic library of A. xylinum in a Xanthomonas campestris mutant defective in xanthan polysaccharide synthesis. The A. xylinum cosmid clone can functionally complement a xanthan-negative mutant. The polymer produced by the recombinant strain was found to be indistinguishable from xanthan. Insertion mutagenesis and subcloning of the cosmid clone combined with complementation studies allowed the identification of a 2.3-kb fragment of A. xylinum chromosomal DNA. The nucleotide sequence of this fragment was analyzed and found to contain an open reading frame (aceA) of 1,182 bp encoding a protein of 43.2 kDa. Results from biochemical and genetic analyses strongly suggest that the aceA gene encodes the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase enzyme, which is responsible for the transfer of an alpha-mannosyl residue from GDP-Man to cellobiosyl-diphosphopolyprenol. A search for similarities with other known mannosyltransferases revealed that all bacterial alpha-mannosyltransferases have a short COOH-terminal amino acid sequence in common.

Vectors with the fd replicon for in vivo cloning and analysis of genes

We have constructed two new mini-Mu derivatives, pMRfP and pBEf, that combine the properties of known mini-Mu vectors and the advantages of the replication origin (orifd) of filamentous phage fd. Mini-Mu pMRfP consists of the left (850 bp) and the right (216 bp) ends of the Mu genome, orifd, packaging signal of fd, and the gene conferring resistance to chloramphenicol. The second mini-Mu, termed pBEf, carries the left end of Mu (1001 bp), which contains the so-called internal activation sequence (enhancer of transposition), required for a higher frequency of transposition, the right end (116 bp) and the gene conferring resistance to kanamycin. These new mini-Mu vectors are suitable for in vivo cloning with the ability of single-stranded DNA preparation using one of the helper phages (M13K07, rv1, IR1, R408) and with a large cloning capacity (the size of the cloned fragment can be up to 35 kb). They can also be used as the hoppers (a transposable ori that can be turned on or off depending on the presence of the fd gene 2 product). Thus, these mini-Mu derivatives can be employed as vectors for in vivo cloning, and as regulated transposons or mobile replicons.

Application of the mini-mu phage for the isolation of lac transcriptional fusions in Bacillus subtilis genes

A cassette containing a selectable cat gene and the lacZ gene without its own promoter has been incorporated into the mini-Mu bacteriophage genome. This mini-Mu derivative, referred to as mMu-Bs, can be used in Escherichia coli for the generation of lacZ transcriptional fusions to Bacillus subtilis genes cloned into plasmids. The resultant fusions can be analyzed in B. subtilis either as multicopy plasmids or as a single copy integrated via a Campbell-like recombination into the wild-type locus of the cloned fragment.

Expression of cloned genes by in vivo insertion of tac promoter using a mini-Mu bacteriophage

The strong trp-lac(tac) promoter has been incorporated into the mini-Mu bacteriophage genome to form a mini-Mu-tac (mMu-tac) expression transposon. This mMu-tac element can transpose efficiently in Escherichia coli cells when derepressed and occasionally insert into a recombinant plasmid. When mMu-tac integration occurs upstream of a cloned gene in the orientation of its transcription, the tac promoter can direct the expression of the gene insert. mMu-tac contains translation stop codons downstream of the tac promoter. Thus, mMu-tac should be useful to express only those genes containing their own translational information. We report here the successful expression in E. coli of several prokaryotic genes using the transposon expression system.

A cos-mini-Mu vector for in vivo DNA cloning

Construction of a mini-Mu plasmid vector containing a cosmid replicon is described. Upon derepression of mini-Mu transposition, bacterial DNA sequences can be flanked by the integrated mini-Mu. These sequences can then be packaged into lambda heads by superinfection with a lambda helper phage. Cosmid clones carrying particular bacterial genes can be recovered by selection after infection of appropriate strains with the cosmid transducing lambda lysate. We report here the successful in vivo cloning of several Escherichia coli genes using the transposoncosmid vector.

In vivo cloning of DNA into multicopy cosmids by mini-Mu-cosduction

A general in vivo procedure for cloning Escherichia coli genes into cosmids has been developed. The method we describe here uses a deleted Mu phage (a mini-Mu) to transpose E. coli genes into cosmids during mini-Mu replication. The resulting cosmids clones are packaged in vivo into lambda phage particles. Plasmids carrying a particular DNA sequence can be selectively recovered after infection of a new host with the in vivo constructed genomic cosmid library. This system was used successfully to clone several E. coli genes.