Abstract:
Beta ketoacyl-ACP synthase I (KAS I) is a fatty acid synthase (FAS) that catalyze the
elongation of growing fatty acid chains from butyryl-ACP (C4:0) to palmitoyl-ACP
(Cl 6:0). In this study, the partial-length of KAS I cDNA clone was isolated and
characterized to understand the regulatory mechanism of fatty acid biosynthesis
pathway in Chiarella sp. at molecular level. Four heterologous forward primers
designed from the conserved regions of the KAS I gene were used in combination
with KPN-adaptor reverse primer to amplify the corresponding 3'-end region of the
gene by using RT-PCR technique. PCR amplification successfully produced five
putative DNA fragments with size ranging between 600 bp to 1000 bp. Cloning and
sequencing of the fragments revealed that clone designated as pKASI-Ch5 showed
significant (74-75%) nucleotide and amino acid sequence identities to KAS I gene
from various plant species such as Helianthus annus, Glycine max and Arabidopsis
thaliana. The pKAS1-Ch5 clone (1008 bp) consists of 639 bp open reading frame
(ORF) encoding a partial KAS I polypeptide of 213 amino acids with a 369 bp long
3 '-untranslated region. This sequence had been registered in GenBank under accession
number EU590913. The isolation of this KAS I cDNA clone is a significant step
towards the genetic manipulation of marine microalgae to enhance the production of
saturated fatty acids for biodiesel industry.
