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PubMed2002

Enhanced detection and characterization of protocatechuate 3,4-dioxygenase in Acinetobacter lwoffii K24 by proteomics using a column separation.

Acinetobacter lwoffii K24 known as an aniline degrading bacterium has also been found to utilize p-hydroxybenzoate as a sole carbon source. In this study, 2-DE using Q-Sepharose column separation was attempted for fast screening of protocatechuate 3,4-dioxygenase for catabolism of p-hydroxybenzoate in A. lwoffii K24. Two protocatechuate 3,4-dioxygenase subunits, pcaG and pcaH were detected and identified with N-terminal and internal sequencing, suggesting proteomics using a column separation may be helpful for the identification of specific protein spots and maximizing the detectable protein spots on the 2-DE gel. The PCR process using degenerate primers for protocatechuate 3,4-dioxygenase and sequence analyses of the PCR products revealed the existence of pcaH and pcaG in A. lwoffii K24. These two subunits were found to be closely located and share extensive homology with pcaH and pcaG of Pseudomonas marginata or Pseudomonas cepacia, providing the evidence that A. lwoffi K24 has the protocatechuate branches as well as catechol branches of beta-ketoadipate pathway.

Acinetobacter↗
PubMed2002

A novel beta-diketone-cleaving enzyme from Acinetobacter johnsonii: acetylacetone 2,3-oxygenase.

A novel Fe+Zn containing oxygenase from Acinetobacter johnsonii catalyses 2,3-cleavage of acetylacetone to acetate and methylglyoxal has been purified. The stoichiometry of reactants and products conforms to a classical dioxygenase. The pure protein is a homotetramer of 64kD with variable amounts of Fe(2+) and Zn(2+). Activity of the enzyme is more closely related to the Fe(2+) content than to the amount of protein. A purification of acetylacetone 2,3-oxygenase, some of its physical properties, and the preference for some analogous substrates are described.

Acinetobacter↗
PubMed1992

Phosphorylation of Acinetobacter isocitrate lyase.

During growth on succinate, Acinetobacter calcoaceticus contains two forms of the enzyme isocitrate dehydrogenase. Addition of acetate to a lag-phase culture grown on succinate causes a dramatic increase in activity of form II of isocitrate dehydrogenase and in isocitrate lyase. Form II of isocitrate dehydrogenase may be responsible for the partition of isocitrate between the TCA cycle and the glyoxylate by-pass. This report describes the phosphorylation of the enzyme isocitrate lyase from A. calcoaceticus. This phosphorylation may be a regulatory mechanism for the glyoxylate by-pass.

Acinetobacter calcoaceticus↗
PubMed2000

Synthesis of neoglycoproteins containing D-glycero-D-talo-oct-2-ulopyranosylonic acid (Ko) ligands corresponding to core units from Burkholderia and Acinetobacter lipopolysaccharide.

Glycal esters of Kdo derivatives were converted into 2,3-anhydro intermediates, which were transformed into D-glycero-D-talo-oct-2-ulopyranosylonic acid (Ko), as well as 3-O- and 4-O-p-nitrobenzoyl-Ko derivatives. The exo-allyl orthoester derivative, methyl [5,7,8-tri-O-acetyl-4-O-(4-nitrobenzoyl)-2,3-O-[(1-exo-allyloxy)-ethylidene]-D-glycero-beta-D-talo-oct-2-ulopyranos]onate, prepared from the 4-O-pNBz-protected Ko derivative, was elaborated into the alpha-Ko allyl ketoside, the reducing disaccharide alpha-Kdop-(2-->4)-Ko and the disaccharide alpha-Kdop-(2-->4)-Kop-(2-->OAll). Conversely, methyl[4,5,7,8-tetra-O-acetyl-3-O-(4-nitrobenzoyl)-alpha-D-glycero-D-talo-2-octulopyranosyl bromide]onate [Carbohydr. Res., 244 (1993) 69-84], was coupled with a Kdo acceptor to give the disaccharide alpha-Kop-(2-->4)-Kdop-(2-->OAll) after orthoester rearrangement and deprotection. The allyl glycosides were treated with cysteamine and converted into neoglycoproteins. The ligands correspond to inner core units from Acinetobacter haemolyticus and Burkholderia cepacia lipopolysaccharides.

Acinetobacter↗
PubMed1997

Structure of the O18 antigen from Acinetobacter baumannii.

The polymeric O antigen was obtained from lipopolysaccharide extracted from isolated, defatted cell walls of the reference strain for Acinetobacter baumannii serogroup O18. Monosaccharide analyses and NMR spectra established that the polymer had a regular structure with a repeating unit based on residues of D-galactose (2), N-acetyl-D-galactosamine (1), and N-acetyl-D-mannosamine (1). Further interpretation of the NMR spectra, combined with the results of methylation analysis and a Smith degradation, showed that the repeating unit had the following structure. beta-D-ManpNAc-(1-->4)-alpha-D-Galp 1 decreases 4 -->3)-beta-D-GalpNAc-(1-->3)-beta-D-Galp-(1-->.

Acinetobacter↗
PubMed1998

Structure of the O-7 antigen from Acinetobacter baumannii.

The polymeric O-antigen was isolated from the lipopolysaccharide of the reference of the reference strain for Acinetobacter baumannii serogroup O-7. Both the lipopolysaccharide and the isolated polymer reacted with the homologous antiserum. Monosaccharide analyses and NMR spectra showed that the polymer had a hexasaccharide repeating unit constructed from residues of L-rhamnose (4) and N-acetyl-D-glucosamine (2). The following structure for the repeating unit was established by means of detailed interpretation of the NMR spectra, methylation analysis, and chemical degradations. The tetrasaccharide backbone is identical to that for the O-10 antigen of A. baumannii, which has alpha-D-ManpNAc as the lateral substituent in place of the disaccharide present in the O-7 antigen. [formula: see text]

Acinetobacter↗
PubMed1999

Structure of the O-specific polysaccharide for Acinetobacter baumannii serogroup O1.

A polymeric fraction containing D-galactose, N-acetyl-D-galactosamine, and N-acetyl-D-glucosamine was isolated from the lipopolysaccharide produced by the reference strain for Acinetobacter baumannii serogroup O1. By means of NMR spectroscopy, methylation analysis, and chemical degradation, the repeating unit of the polymer was identified as a branched trisaccharide of the following structure. [formula: see text].

Acinetobacter↗
PubMed1999

Purification and characterization of a major 40 kDa outer membrane protein of Acinetobacter baumannii.

Acinetobacter baumannii, an opportunistic pathogen, is well known to cause a wide spectrum of nosocomial infections particularly in intensive care units. The major outer membrane (OM) protein, OmpAb, of 40 kDa from A. baumannii has been identified and purified to homogeneity from cultures grown at 30 degrees C and 100 mM NaCl. The synthesis of OM proteins of A. baumannii is thermoregulated and osmoregulated. The pore forming ability of the purified OmpAb and the diffusion of uncharged solutes in proteoliposomes has been demonstrated by following the liposomal swelling assay. The trimeric OmpAb is characterized as a porin with a pore size of 1.3 nm and is found to be similar to the OmpF of Escherichia coli and can possibly be classified as a general diffusion pore. It appears that OmpAb plays an important role in the diffusion properties of the outer membrane of A. baumannii.

Acinetobacter↗
PubMed1999

On the binding of ATP to the autophosphorylating protein, Ptk, of the bacterium Acinetobacter johnsonii.

The autophosphorylating protein, Ptk, of the bacterium Acinetobacter johnsonii was overproduced, purified to homogeneity and assayed for ATP binding by using the nucleotide analog 5'-p-fluorosulfonylbenzoyl adenosine. The ATP binding site of this bacterial autophosphorylating protein was found to be different from that generally used by eukaryotic protein kinases. It consists of two amino acid sequences that closely resemble the Walker motifs A and B. This observation was confirmed by site-directed mutagenesis experiments which showed, in addition, that the ATP molecule bound to these motifs is effectively employed by the bacterial protein to autophosphorylate on tyrosine. It is concluded that even though the overall autophosphorylation reaction is similar in eukaryotic and prokaryotic proteins, the mechanism involved is likely different.

Acinetobacter↗
PubMed2002

X-ray crystal structure of benzoate 1,2-dioxygenase reductase from Acinetobacter sp. strain ADP1.

One of the major processes for aerobic biodegradation of aromatic compounds is initiated by Rieske dioxygenases. Benzoate dioxygenase contains a reductase component, BenC, that is responsible for the two-electron transfer from NADH via FAD and an iron-sulfur cluster to the terminal oxygenase component. Here, we present the structure of BenC from Acinetobacter sp. strain ADP1 at 1.5 A resolution. BenC contains three domains, each binding a redox cofactor: iron-sulfur, FAD and NADH, respectively. The [2Fe-2S] domain is similar to that of plant ferredoxins, and the FAD and NADH domains are similar to members of the ferredoxin:NADPH reductase superfamily. In phthalate dioxygenase reductase, the only other Rieske dioxygenase reductase for which a crystal structure is available, the ferredoxin-like and flavin binding domains are sequentially reversed compared to BenC. The BenC structure shows significant differences in the location of the ferredoxin domain relative to the other domains, compared to phthalate dioxygenase reductase and other known systems containing these three domains. In BenC, the ferredoxin domain interacts with both the flavin and NAD(P)H domains. The iron-sulfur center and the flavin are about 9 A apart, which allows a fast electron transfer. The BenC structure is the first determined for a reductase from the class IB Rieske dioxygenases, whose reductases transfer electrons directly to their oxygenase components. Based on sequence similarities, a very similar structure was modeled for the class III naphthalene dioxygenase reductase, which transfers electrons to an intermediary ferredoxin, rather than the oxygenase component.

Acinetobacter↗
PubMed1997

Incorporation of 2-hydroxyl fatty acids by Acinetobacter calcoaceticus RAG-1 to tailor emulsan structure.

Acinetobacter calcoaceticus RAG-1 was cultured on different chain length saturated 2-hydroxyl fatty acid (2-HOFA) carbon sources as follows: C12:0 (2-OH), C14:0 (2-OH), C16:0 (2-OH) and C18:0 (2-OH). These 2-HOFAs were used as either sole carbon sources or cosubstrates with C14:0 (total 1% w/v) to form new emulsans (EMs) having controlled side chain FA structure and, therefore, unique emulsifier characteristics. EM yields and cell dry weights ranged from 0.6 to 1.8 g/l and 0.9 to 3.9 g/l, respectively, depending on the carbon source(s) and the cultivation conditions. The content of C12:0 (2-OH) EM substituents reached high levels (306 nmol/mg-EM, 64.4 mol% of total FAs) by selectively feeding this FA. Substantial quantities of 2-HOFAs with chain lengths > or = C14-up to 96 nmo1/mg-EM or 15.2 mol% for C16:0 (2-OH)-were also incorporated in EMs by providing the corresponding 2-HOFA carbon source in the medium. By increasing the medium 2-HOFA concentration large increases in EM total FA contents resulted. The EM FA content was as high as 955 nmol/mg-EM or 23 wt% for a culture containing 0.75 g/100 ml C18:0 (2-OH). An important metabolic pathway involved in EM side chain formation from C16:0 (2-OH) and C18:0 (2-OH) involves decarboxylation, oxidation of the alkanol to the corresponding n-1 FA-CoA intermediate and formation of odd chain length substituent side chain linkages by an EM acyl transferase. Addition of the enzyme alkylating agent iodoacetamide to cultures was used to: (i) enhance the incorporation into EMs of both C12:0 (2-OH) and C16:0 (2-OH) substituents; and (ii) increase by 1.3 to 1.8 fold (by wt.) the total EM FA content. Finally, it was concluded that enhanced emulsification activity of EMs is not necessarily achieved by forming products with relatively high 2- and 3-hydroxydodecanoic acid contents.

Acinetobacter calcoaceticus↗
PubMed2003

Characterization of class 1 integron resistance gene cassettes and the identification of a novel IS-like element in Acinetobacter baumannii.

Based on hybridization studies, 21/32 multi-resistant clinical isolates of Acinetobacter baumannii contain class 1 integrons. Amplification products were obtained from 20 of the hybridization-positive strains. A single dfrA7 cassette was identified in 18 of the isolates and an integron with two cassettes (aadB-aadA4) was found in only one strain. Amplicons were not obtained from one of the hybridization positive strains. DNA sequence analysis of a 6.080-kb fragment, cloned from this strain, identified the remnant of an integron, following insertion of IS26 into the 5(')-end of intI1. The 6.080-kb sequence carries an aminoglycoside resistance gene, linked to a portion of IS1133, which in turn is linked to a sequence that has properties of IS elements, including sequences that could stimulate transcription, and ORFs encoding amino acid sequences with similarity to a transposase from Deinococcus radiodurans.

Acinetobacter baumannii↗
PubMed2002

Failure to demonstrate involvement of antibodies to Acinetobacter calcoaceticus in transmissible spongiform encephalopathies of animals.

Acinetobacter calcoaceticus, a soil microbe, contains molecular sequences which resemble those found in neurofilaments of the brain tissue. It was hypothesized that if cattle ingest large amounts of feedstuff containing A. calcoaceticus, they may develop an autoimmune reaction, with consequences of pathological changes associated with transmissible spongiform encephalopathies (TSEs). The hypothesis was tested using a small number of serum samples collected from cattle and it was found that affected individuals had elevated serum antibody levels to this organism. If this finding was substantiated, it would provide a possible means of diagnosing TSEs in vivo. In the present communication, a larger number of cattle, elk and sheep with or without TSEs were tested using A. calcoaceticus whole cell and lipopolysaccharide antigens as well as myelin basic protein (MBP). It was found that antibody levels in normal and affected animals overlapped considerably, thus casting doubt on the usefulness of these antigens as diagnostic tools for TSEs and on the hypothesis of A. calcoaceticus being a cause of TSEs.

Acinetobacter calcoaceticus↗
PubMed2001

Cloning and characterization of a novel gene encoding L-ribose isomerase from Acinetobacter sp. strain DL-28 in Escherichia coli.

The gene encoding a novel L-ribose isomerase (L-RI) from Acinetobacter sp. was cloned into Escherichia coli and nucleotide sequence was determined. The gene corresponded to an open reading frame of 747 bp that codes for a deduced protein of 249 amino acids, which showed no amino acid sequence similarity with any other sugar isomerases. After expression of the gene in E. coli using pUC118 the recombinant L-RI was purified to homogeneity using different chromatographic methods. The overall enzymatic properties of the purified recombinant L-RI were the same as those of the authentic L-RI. To our knowledge, this is the first time report concerning the L-RI gene.

Acinetobacter↗
PubMed1997

Cloning and sequencing of genes encoding malonate decarboxylase in Acinetobacter calcoaceticus.

Malonate decarboxylase from Acinetobacter calcoaceticus was isolated and characterized (Kim, Y.S., Byun, H.S., J. Biol. Chem. 269 (1994) 29636-29641), and its subunits were reanalyzed recently to be alpha, beta, gamma, and delta. The genes for the subunits, MdcA (548 a.a.), B (295 a.a.), C (238 a.a.), and D (102 a.a.), of the enzyme have been cloned by using oligonucleotide primers deduced from amino acid sequences of peptides isolated from the purified enzyme, and sequenced to be clustered in an operon in the order of A-D-B-C. The operon was found to encode more genes than mdcABCD. The Escherichia coli, transformed with the vector containing the insert mdcADBC and about 1.7 kb of an upstream region, expressed the four subunits of the enzyme but the proteins did not show enzyme activity. It indicates that, like the enzymes from Malonomonas rubra and Klebsiella pneumoniae, more genes are needed for the formation of the functional malonate decarboxylase.

Acinetobacter calcoaceticus↗
PubMed2000

Flow cytometric techniques to characterise physiological states of Acinetobacter calcoaceticus.

Monitoring biotechnological processes involves acquiring information about key metabolic events and, ideally, single cell states should be determined to obtain comprehensive data on the physiological status of the surveyed population. In this paper, growth stages of the strain Acinetobacter calcoaceticus 69-V were characterised at the single cell level using flow cytometry. Four methods for analysing bacterial cellular characteristics by fluorescence were compared with respect to their sensitivity to changes in the physiological states induced by changing micro-environmental conditions. DNA analysis was confirmed to be highly informative with regard to the multiplication activity of the population. Measuring the membrane potential related fluorescence intensity (MPRFI) and the rRNA content were found to be useful for describing high-active cell states. A method for the measurement of the fluidity related fluorescence intensity (FRFI) was developed, since it allowed changes in the fluidity of the bacterial membrane to be detected, and thereby provided a valuable means of tracking adaptation of the population to micro-environmental deviations from optimal growth conditions.

Acinetobacter calcoaceticus↗
PubMed2003

Predictive modelling of growth and enzyme production and activity by a cocktail of Pseudomonas spp., Shewanella putrefaciens and Acinetobacter sp.

The possibility was examined of developing a predictive model that combined microbial growth (increase in cellular number) with extracellular lipolytic and proteolytic enzyme activity of a cocktail of four strains of Pseudomonas spp. and one strain each of Acinetobacter sp. and Shewanella putrefaciens. Environmental conditions within the following matrix of conditions were examined: temperature 2-20 degrees C, pH value 4.0-7.5 and water activity (a(w)) 0.95-0.995 and a model was constructed, which predicted growth based on increase in cell number. Data on lipase production and protease activity were generated and will be available as a database, but no function could be identified, which was a good fit to these data, since most enzymatic production and activity occurred, as expected, during transition from exponential to stationary phase. Even at lower cell numbers, in more unfavourable conditions, hydrolysing effects were detectable, which made it difficult to construct a model combining both microbiological and enzymatic data.

Acinetobacter↗
PubMed1996

The use of plasmid profile analysis and ribotyping for typing Acinetobacter baumannii isolates.

Plasmid profiles were used to analyse 39 Acinetobacter baumannii isolates from 36 patients at three hospitals. The isolates were prevously classified by biotyping and rDNA fingerprinting. Ribotyping was useful to establish the lineage of isolates and to confirm genospecies identification. Thirty-seven isolates (94.9%) contained plasmids. The variable number of plasmids with different molecular weights in each isolate enabled the identification of 13 profiles without the need for endonuclease digestion. Fifteen A. baumannii biotype 2 isolates of similar ribotype and antibiotype contained identical plasmids over a two-month outbreak at one hospital. Plasmid typing discriminated these isolates from sporadic A. baumannii isolates of close ribotype obtained from different hospitals. A few isolates of different lineage, however, showed similar plasmid profile. Our results suggest that plasmid typing is a practical method to assist infection control of nosocomial A baumannii. A combination of plasmid typing and ribotyping is suggested to confirm genospecies classification and to identify strains against reference band profiles.

Acinetobacter↗