INVESTIGADORES
ALVAREZ Hector Manuel
artículos
Título:
Cloning and characterization of a gene involved in triacylglycerol biosynthesis and identification of additional homologous genes in the oleogenous bacterium Rhodococcus opacus PD630
Autor/es:
ALVAREZ AF,; ALVAREZ HM; KALSCHEUER R,; WALTERMANN M; STEINBÜCHEL A,
Revista:
MICROBIOLOGY-UK
Editorial:
Society for General Microbiology (SGM)
Referencias:
Lugar: UK; Año: 2008 vol. - p. 2327 - 2335
ISSN:
1350-0872
Resumen:
The oleaginous bacterium Rhodococus opacus strain PD630 serves as a model organism to
investigate the metabolism of storage triacylglycerols (TAGs) in bacteria. The key enzyme
catalysing the last step of TAG biosynthesis in bacteria is a promiscuous acyltransferase (Atf),
exhibiting acyl-CoA acyltransferase activity to both diacylglycerols (DGAT activity) and fatty
alcohols (wax ester synthase, WS activity). An 800 bp PCR product was obtained from
chromosomal DNA of strain PD630 by using degenerate primers designed from conserved
stretches of Atf proteins of Acinetobacter baylyi strain ADP1 and Mycobacterium smegmatis
mc2155. The atf fragment was used as a probe on a strain PD630 gene library, resulting in the
identification of a 3948 bp chromosomal DNA fragment containing the complete atf1 gene. An
atf1 disruption mutant of strain PD630 exhibited a TAG-leaky phenotype and accumulated up to
50% less fatty acids than the wild-type, with significantly reduced oleic acid content when
cultivated in the presence of gluconate or oleic acid. Whereas DGAT activity was drastically
reduced in comparison to the wild-type, WS activity remained almost unchanged in the mutant.
RT-PCR analysis of gluconate-grown cells of strain PD630 showed that there is expression of
atf1 under conditions of TAG synthesis. To identify additional Atfs in strain PD630, PCR
employing non-degenerate primers deduced from Rhodococcus jostii RHA1 sequence data was
used. This yielded nine additional atf-homologous genes exhibiting 8899% sequence identity to
the corresponding strain RHA1 enzymes. Besides Atf1 only Atf2 exhibited high DGAT and/or
WS activity when heterologously expressed in Escherichia coli.