Biomedical subjects

Hae Choon Chang

Publications and source records attributed to Hae Choon Chang.

4 recordsLinked to original sources

PubMed2005

Cloning and characterization of the bifunctional alcohol/acetaldehyde dehydrogenase gene (adhE) in Leuconostoc mesenteroides isolated from kimchi.

A bifunctional alcohol/acetaldehyde dehydrogenase (AdhE) gene (adhE) was cloned from Leuconostoc mesenteroides C7 (LMC7), which is the dominant lactic acid bacterium produced during heterofermentation of kimchi. The nucleotide sequence of the DNA fragment containing putative adhE, which is 2685 bp long and encodes an 886 amino acid polypeptide, exhibits 99% homology with Leu. mesenteroides sp. cremoris. The deduced AdhE comprises two conserved domains: alcohol dehydrogenase (Adh) and acetaldehyde dehydrogenase (Aldh). Moreover, two NAD-binding sites were observed, based on the presence of the GXGXXG motif. A pADHE containing the adhE gene expressed AdhE at the translational level in Escherichia coli BL21, which was at a higher level than in E. coli DH5alpha and E. coli JM109. The AdhE of LMC7 showed Adh and Aldh activities that, when expressed in E. coli. BL21, were 7.5 and 5.7 U mg(-1) , respectively.

Alcohol Dehydrogenase↗

PubMed2005

Cloning and characterization of the gene encoding phosphoketolase in Leuconostoc mesenteroides isolated from kimchi.

The gene encoding phosphoketolase, which is 2749 bp long and contains 814 amino acid polypeptides with a total molecular mass of 91.9 kDa, was cloned from Leuconostoc mesenteroides C7 (LMC7) and expressed in Escherichia coli. It exhibited a homology of >58% with phosphoketolases from other lactic acid bacteria. The phosphoketolase of LMC7 belongs to the xylulose 5-phosphate (X5P)/fructose 6-phosphate (F6P) phosphoketolase (Xfp) family, which is an enzyme with dual specificity for X5P and F6P. The members of this family contain typical thiamin pyrophosphate (TPP) binding sites as reported for other TPP-dependent enzymes, and several highly conserved regions as signature patterns for phosphoketolases. The plasmid pGPK containing the Xfp gene (xfp) exhibits phosphoketolase activity in E. coli. The specific activities of the enzyme from E. coli BL21 and E. coli EC101 harboring xfp were 0.28 and 0.14 units/mg, respectively. They both exhibited a 1.5-fold increase in the production of acetic acid from acetyl phosphate compared with their corresponding original strain.

Aldehyde-Lyases↗

PubMed2004

Characterization of pC7 from Lactobacillus paraplantarum C7 derived from Kimchi and development of lactic acid bacteria--Escherichia coli shuttle vector.

A cryptic plasmid pC7 was characterized, which was isolated from Lactobacillus paraplantarum C7 derived from Kimchi, a traditional korean vegetable food. The plasmid pC7 is a circular molecule of 2,134 base-pairs in length with a G + C content of 38.5%. The nucleotide sequence analysis revealed the presence of an open reading frame encoding a putative 317 amino acids protein homologous to replication proteins RepA. Furthermore, a putative double and a single-strand origin were identified. Together with features of nucleotide sequences, the detection of single-stranded intermediate DNA in Lb. paraplantarum demonstrated that pC7 replicates via a rolling circle mechanism. A cloning vector for lactic acid bacteria was developed on the basis of the pC7 replicon, into which were inserted an erythromycin resistance gene as a marker, multiple cloning sites, and Escherichia coli ColE1 replication origin. E. coli and several species of Lactobacillus and Leuconostoc can be transformed with the resultant vector. Therefore, pC7 derivatives may be useful LAB-E. coli shuttle vectors, which are essential in engineering important strains in food fermentation.

Amino Acid Sequence↗

PubMed2003

New integration vector using a cellulase gene as a screening marker for Lactobacillus.

The new integration vector for Lactobacillus, pJC4, was developed using the extracellular endoglucanase A gene (celA) of Clostridium thermocellum as a screening marker. pJC4 was transformed into four Lactobacillus species, Lb. johnsonii, Lb. gasseri, Lb. bulgaricus, and Lb. plantarum. In each species, the pJC4 integrants were easily and accurately detected by the appearance of a clear halo on a cellulase screening plate without any false transformants. Polymerase chain reaction and Southern hybridization indicated that all transformants with clear halos contained pJC4 in their chromosomal DNAs. The celA gene could be a useful screening marker for other lactic acid bacteria.

Cellulase↗