Structure, Distribution and Function of Wax Esters in Acinetobacter calcoaceticus

Fixter, L. M.; Nagi, Mahmoud N.; McCormack, James G.; Fewson, Charles A.

doi:10.1099/00221287-132-11-3147

Cited by 69 publications

(88 citation statements)

References 27 publications

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“…The accumulation of large amounts of TAGs in bacteria has been frequently reported in strains belonging to the order Actinomycetales such as Mycobacterium (Barksdale & Kim, 1977), Streptomyces (Olukoshi & Packter, 1994;Packter & Olukoshi, 1995), Nocardia and Rhodococcus (Alvarez et al, 1996(Alvarez et al, , 1997a. Moreover, biosynthesis of wax esters (WEs) has often been reported for Acinetobacter species (Fixter et al, 1986). Biosynthesis of WEs has also been sporadically reported in species of the genera Moraxella (Bryn et al, 1977), Micrococcus (Russell & Volkman, 1980) and Alcanivorax (Bredemeier et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Cloning and characterization of a gene involved in triacylglycerol biosynthesis and identification of additional homologous genes in the oleaginous bacterium Rhodococcus opacus PD630

et al. 2008

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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 mc 2 155. 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 88-99 % 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.

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Section: Introductionmentioning

confidence: 99%

Cloning and characterization of a gene involved in triacylglycerol biosynthesis and identification of additional homologous genes in the oleaginous bacterium Rhodococcus opacus PD630

et al. 2008

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“…Species of the Gram-negative genus Acinetobacter are also able to synthesize TAG, but they accumulate only minor amounts. In contrast to others, these organisms accumulate mainly WE as storage lipids (25)(26)(27).…”

Section: Tag and We In Prokaryotesmentioning

confidence: 99%

“…Highest enzymatic activities were measured with C 16 -CoA and linear C 14 to C 18 fatty alcohols (54). Under natural conditions, WE of 32 to 36 carbon atoms represent the main proportion of WE synthesized in A. baylyi (25,55).…”

Section: Atfa From a Baylyi Adp1: A Bacterial Model Enzyme For We Anmentioning

confidence: 99%

Acyltransferases in Bacteria

Röttig

Steinbüchel

2013

Microbiol Mol Biol Rev

151

141

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SUMMARY Long-chain-length hydrophobic acyl residues play a vital role in a multitude of essential biological structures and processes. They build the inner hydrophobic layers of biological membranes, are converted to intracellular storage compounds, and are used to modify protein properties or function as membrane anchors, to name only a few functions. Acyl thioesters are transferred by acyltransferases or transacylases to a variety of different substrates or are polymerized to lipophilic storage compounds. Lipases represent another important enzyme class dealing with fatty acyl chains; however, they cannot be regarded as acyltransferases in the strict sense. This review provides a detailed survey of the wide spectrum of bacterial acyltransferases and compares different enzyme families in regard to their catalytic mechanisms. On the basis of their studied or assumed mechanisms, most of the acyl-transferring enzymes can be divided into two groups. The majority of enzymes discussed in this review employ a conserved acyltransferase motif with an invariant histidine residue, followed by an acidic amino acid residue, and their catalytic mechanism is characterized by a noncovalent transition state. In contrast to that, lipases rely on completely different mechanism which employs a catalytic triad and functions via the formation of covalent intermediates. This is, for example, similar to the mechanism which has been suggested for polyester synthases. Consequently, although the presented enzyme types neither share homology nor have a common three-dimensional structure, and although they deal with greatly varying molecule structures, this variety is not reflected in their mechanisms, all of which rely on a catalytically active histidine residue.

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“…The accumulation of TAGs in large quantities has so far been described only for certain gram-positive bacteria of the actinomycetes group, belonging to the genera Mycobacterium, Nocardia, Rhodococcus, and Streptomyces (2). In contrast, WEs (oxoesters of long-chain primary fatty alcohols and long-chain fatty acids), along with small amounts of TAGs, seem to be common storage lipids within the gram-negative genus Acinetobacter (12,13,14,22). Recently, the key enzyme for storage lipid biosynthesis in Acinetobacter baylyi strain ADP1 (formerly Acinetobacter sp.…”

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confidence: 99%

Analysis of Storage Lipid Accumulation in Alcanivorax borkumensis : Evidence for Alternative Triacylglycerol Biosynthesis Routes in Bacteria

et al. 2007

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Marine hydrocarbonoclastic bacteria, like Alcanivorax borkumensis, play a globally important role in bioremediation of petroleum oil contamination in marine ecosystems. Accumulation of storage lipids, serving as endogenous carbon and energy sources during starvation periods, might be a potential adaptation mechanism for coping with nutrient limitation, which is a frequent stress factor challenging those bacteria in their natural marine habitats. Here we report on the analysis of storage lipid biosynthesis in A. borkumensis strain SK2. Triacylglycerols (TAGs) and wax esters (WEs), but not poly(hydroxyalkanoic acids), are the principal storage lipids present in this and other hydrocarbonoclastic bacterial species. Although so far assumed to be a characteristic restricted to gram-positive actinomycetes, substantial accumulation of TAGs corresponding to a fatty acid content of more than 23% of the cellular dry weight is the first characteristic of large-scale de novo TAG biosynthesis in a gram-negative bacterium. The acyltransferase AtfA1 (ABO_2742) exhibiting wax ester synthase/acyl-coenzyme A:diacylglycerol acyltransferase (WS/DGAT) activity plays a key role in both TAG and WE biosynthesis, whereas AtfA2 (ABO_1804) was dispensable for storage lipid formation. However, reduced but still substantial residual TAG levels in atfA1 and atfA2 knockout mutants compellingly indicate the existence of a yet unknown WS/DGAT-independent alternative TAG biosynthesis route. Storage lipids of A. borkumensis were enriched in saturated fatty acids and accumulated as insoluble intracytoplasmic inclusions exhibiting great structural variety. Storage lipid accumulation provided only a slight growth advantage during short-term starvation periods but was not required for maintaining viability and long-term persistence during extended starvation phases.

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Structure, Distribution and Function of Wax Esters in Acinetobacter calcoaceticus

Cited by 69 publications

References 27 publications

Cloning and characterization of a gene involved in triacylglycerol biosynthesis and identification of additional homologous genes in the oleaginous bacterium Rhodococcus opacus PD630

Cloning and characterization of a gene involved in triacylglycerol biosynthesis and identification of additional homologous genes in the oleaginous bacterium Rhodococcus opacus PD630

Acyltransferases in Bacteria

Analysis of Storage Lipid Accumulation in Alcanivorax borkumensis : Evidence for Alternative Triacylglycerol Biosynthesis Routes in Bacteria

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