type	Journal Article
authors	Bae, J.H.; Sohn, J.H.; Park, C.S.; Rhee, J.S.; Choi, E.S.
title	Integrative transformation system for the metabolic engineering of the sphingoid base-producing yeast Pichia ciferrii
journal	Appl Environ Microbiol
Activity	2.3.1.50
Family	2.3.1.50.b
sel	selected
ui	12570999
year	(2003)
volume	69
number	2
pages	812-9
keywords	Acyltransferases
abstract	We have developed an integrative transformation system for metabolic engineering of the tetraacetyl phytosphingosine (TAPS)-secreting yeast Pichia ciferrii. The system uses (i) a mutagenized ribosomal protein L41 gene of P. ciferrii as a dominant selection marker that confer resistance to the antibiotic cycloheximide and (ii) a ribosomal DNA (rDNA) fragment of P. ciferrii as a target for multicopy gene integration into the chromosome. A locus within the nontranscribed region located between 5S and 26S rDNAs was selected as the integration site. A maximum frequency of integrative transformation of approximately 1,350 transformants/ microg of DNA was observed. To improve the de novo synthesis of sphingolipid, the LCB2 gene, encoding a subunit of serine palmitoyltransferase, which catalyzes the first committed step of sphingolipid synthesis, was cloned from P. ciferrii and overexpressed under the control of the P. ciferrii glyceraldehyde-3-phosphate dehydrogenase promoter. After transformation of an LCB2 gene expression cassette, several transformants that contained approximately five to seven copies of transforming DNA in the chromosome and exhibited about 50-fold increase in LCB2 mRNA relative to the wild type were identified. These transformants were observed to produce approximately two times more TAPS than the wild type.
last changed	2007/10/18 13:12