Lysine Decarboxylase Activity Research Articles

Development of a continuous l-lysine bioconversion system for cadaverine production

Abstract Cadaverine, a five carbon diamine (1,5-diaminopentane), plays a role as a building block of polyamides and it can be made by fermentation or direct bioconversion. To improve its production by increasing reusability of immobilized enzyme and avoid separation of enzyme in bioconversion, a continuous l -lysine bioconversion process for cadaverine production has been developed. Various divalent cations, alginate concentrations, cell density with alginate and flow rate of feed were examined to maximize the lysine decarboxylase activity of the whole-cell immobilized beads. Under the selected conditions, 123 h of continuous cadaverine production has been performed and 5.5 L of 819 mM cadaverine were produced with 14 mL reactor resulting in 466.5 g of cadaverine. Cadaverine production was possible with small volume reactor maintaining relatively high concentration of substrate.

Heat and acid resistance depend on growth pH in the food-borne pathogen Bacillus cereus ATCC 14579

Bacillus cereus is a toxin producing bacterium responsible for food-borne toxi-infections. To monitor the ability of the food-borne opportunistic pathogen Bacillus cereus to survive during minimal processing of food products conditions were established which allowed the cells to adapt to heat and acid stresses. Cells were grown in chemostat at different pH (7.0 and 5.5) and at a growth rate of 0,2 h-1 . Cells were submitted during 40 minutes to an acid shock at pH 4 or to a heat shock at 50°C. The effect of preadaptation at a subletal temperature (42°C -15 min) was studied. Cells grown at low pH (pH 5.5) shown an acid stress adaptation with induction of an Acid Tolerance Response (ATR). Cross-adaptations was observed between thermotolerance and acidotolerance which suggested that a common mechanism was involved in the acid and heat stress responses in B. cereus ATCC 14579. Adaptive levels of stressor were found to induce the over expression of different genes encoding classical heat shock proteins such as dnaK, dnaJ sigB and GroEL and gene involved in internal pH homeostasis encoding ATPase, arginine decarboxylase or deiminase and lysine decarboxylase activities. These data shown that during mild processing, a cross-protection between acid and heat was occurred in B. cereus. These common mechanisms between acid and heat stress response may result in increasing survival of B. cereus cells in foods and can rising the pathogenicity of this bacteria. The virulence of this bacterium poses a major problem in public health in food poisoning.

Biofilm Lysine Decarboxylase, a New Therapeutic Target for Periodontal Inflammation

Lysine, a nutritionally essential amino acid, enters the oral cavity in gingival crevicular fluid (GCF). During oral hygiene restriction (OHR), lysine decarboxylase (LDC) in dento-gingival biofilms converts lysine to cadaverine. Lysine depletion impairs the dental epithelial barrier to bacterial proinflammatory products. Antibodies to LDC from Eikenella corrodens (Ecor-LDC) inhibit LDC activity and retard gingival inflammation in beagle dogs. Whether E. corrodens is the major source of LDC in dental biofilms and whether the lysine analog tranexamic acid (TA) inhibits LDC activity, biofilm accumulation, and GCF exudation in a human gingivitis model were examined. Antibodies raised in goats to LDC-rich extracts from E. corrodens cell surfaces were used to inhibit Ecor-LDC and detect it in biofilm extracts using Western blots. Ecor-LDC activity was measured at pH 4.0 to 11.0 and its TA dissociation constant (Ki) at pH 7.0. Young adults used a 5% or 10% TA mouthwash three times daily during OHR for 1 week. Ecor-LDC antibodies and TA inhibited biofilm LDC. Ki of TA for Ecor-LDC was 940 μM. TA reduced plaque index (PI) by downshifting the PI correlation with biofilm lysine content after OHR without TA. GCF was correspondingly suppressed. However, greater TA retention in saliva partially relieved GCF suppression but not biofilm lysine depletion. TA slightly inhibits LDC but strongly reduces biofilm by inhibiting bacterial lysine uptake. Unfortunately, TA may impair dental epithelial attachments by also inhibiting lysine transporter uptake. Ecor-LDC inhibitors other than lysine analogs may maintain sufficient lysine levels and attachment integrity to prevent periodontal inflammation.

Biotransformation of lysine into cadaverine using barium alginate-immobilized Escherichia coli overexpressing CadA.

In this study, Escherichia coli cells overexpressing lysine decarboxylase (CadA) were used for cadaverine production. Barium alginate was selected as a matrix for immobilization of E. coli YH91. Free cells and immobilized cells (IC) were characterized for their physiochemical properties, and the optimum pH and temperature were determined as 6 and 37 °C, respectively. Immobilized cells were three times more thermally stable compared to free cells at the optimum temperature and had a half-life (t 1/2) of 131 h. The free cells lost most of lysine decarboxylase activity after nine cycles, but in contrast immobilized cells retained 56% of their residual activity even after the 18th cycle. The immobilized cells gave a maximum production of cadaverine (75.8 g/L) with 84% conversion.

A Liquid-Based Colorimetric Assay of Lysine Decarboxylase and Its Application to Enzymatic Assay.

A liquid-based colorimetric assay using a pH indicator was introduced for high-throughput monitoring of lysine decarboxylase activity. The assay is based on the color change of bromocresol purple, measured at 595 nm in liquid reaction mixture, due to an increase of pH by the production of cadaverine. Bromocresol purple was selected as the indicator because it has higher sensitivity than bromothymol blue and pheonol red within a broad range and shows good linearity within the applied pH. We applied this for simple determination of lysine decarboxylase reusability using 96-well plates, and optimization of conditions for enzyme overexpression with different concentrations of IPTG on lysine decarboxylase. This assay is expected to be applied for monitoring and quantifying the liquid-based enzyme reaction in biotransformation of decarboxylase in a high-throughput way.

Directed evolution and mutagenesis of lysine decarboxylase from Hafnia alvei AS1.1009 to improve its activity toward efficient cadaverine production

Lysine decarboxylase (LDC) exhibits a significant role in cadaverine (1,5-pentanediamine, diaminopentane) production from lysine. In this study, an error-prone PCR and DNA shuffling were performed to improve the activity of LDC from Hafnia alvei AS1.1009 for cadaverine production. A sensitive high-throughput screening strategy based on a pH indicator was established for directed evolution of LDC. Several improved mutants were obtained from directed evolution and LDCV147F/E583G mutant showed highest activity to catalyze lysine to cadaverine. This mutant showed 1.62-fold high LDC activity when compared to wild-type. Further analysis by site-directed mutagenesis reveled that only the mutant E583G was sufficient for higher catalytic activity. Wild type LDC and mutant LDCE583G were purified by an improved method including hydrophobic chromatography. These purified enzymes were characterized and the kinetic parameters were compared between LDCE583G and WT LDC. V max of LDCE583G was 1.32-fold higher than that of WT LDC. Use of LDCE583G mutant showed 1.48-fold improved productivity of cadaverine when compared to wild type. The concentration of cadaverine in E. coli JM109/pTrc99a-ldc2-41 was 63.9 g/L with conversion yield of 93.4% during 5 h. These results indicate that the mutation has positive effects on improving LDC activity and a potential candidate for cadaverine production.

Changes in amino acid decarboxylation in maize (Zea mays; Poaceae) tissues in response to bird cherry-oat aphid (Rhopalosiphum padi; Aphididae) infestation

The study was focused on changes in the activities of ornithine decarboxylase (ODC), lysine decarboxylase (LDC) and tyrosine decarboxylase (TyDC) in maize seedlings infested by bird cherry-oat aphid (Rhopalosiphum padi L.).Obtained results showed that the aphid infestation induced LDC activity strongly within tissues of less aphid-settled maize (Waza cv.) during the first week of the infestation in comparison to the control plants and the activity was suppressed after two weeks. However, TyDC activity fluctuated under the aphid infestation. In relation to the control, the enzyme activity was inhibited on the first day, activated after the first week and reduced again two weeks into the experiment. A significant reduction in ODC activity was also observed in seedlings of aphid-infested maize Waza cv. during the first week. In a more susceptible maize cv. (Złota Karłowa), an increase in LDC and TyDC activities in relation to the control and a simultaneous decrease in ODC activity were noted after the first day of the infestation. After one week of aphid attack, TyDC activity was induced and ODC was inhibited, whereas after two weeks ODC activity was decreased with a simultaneous increase in LDC activity in the Złota Karłowa seedlings.

Aquipuribacter nitratireducens sp. nov., isolated from a soil sample of a mud volcano.

A novel Gram-stain-positive, coccoid, non-motile bacterium, designated strain AMV4T, was isolated from a soil sample collected from a mud volcano located in the Andaman Islands, India. The colony was pale orange. Strain AMV4T was positive for oxidase, aesculinase, lysine decarboxylase and ornithine decarboxylase activities and negative for amylase, catalase, cellulase, protease, urease and lipase activities. 16S rRNA gene sequence analysis indicated that strain AMV4T was a member of the order Actinomycetales and was closely related to Aquipuribacter hungaricus with a sequence similarity of 97.13% (pairwise alignment). Phylogenetic analyses showed that strain AMV4T clustered with Aquipuribacter hungaricus and was distantly related to the other genera of the family Intrasporangiaceae. DNA-DNA hybridization between strains AMV4T and Aquipuribacter hungaricus IV-75T showed a relatedness of 28%. The predominant cellular fatty acids were iso-C15 : 0 (6.9%), anteiso-C15 : 0 (25.3%), C16 : 0 (12.9%), anteiso-C16 : 0 (5.6%), C18 : 1ω9c (19.8%) and C18 : 3ω6,9,12c (9.1%). The diagnostic diamino acid in the cell-wall peptidoglycan of strain AMV4T was meso-diaminopimelic acid. Strain AMV4T contained MK-10(H4) as the predominant respiratory quinone. The polar lipids consisted of phosphatidylglycerol, one unidentified glycolipid, two unidentified phospholipids and five unidentified lipids. The DNA G+C content of strain AMV4T was 74.3 mol%. Based on data from this taxonomic study using a polyphasic approach, it is proposed that strain AMV4T represents a novel species of the genus Aquipuribacter, with the suggested name Aquipuribacter nitratireducens sp. nov. The type strain is AMV4T ( = CCUG 58430T = DSM 22863T = NBRC 107137T).

Application of diethyl ethoxymethylenemalonate (DEEMM) derivatization for monitoring of lysine decarboxylase activity

Aliphatic diamines have been used as chemical reagents for the monomers of polyamides (i.e., Nylon 46, Nylon 510, Nylon 66, Nylon 610 and so on), and can be made from lysine, arginine or ornithine by the metabolism of microbes through decarboxylases. However, the conventional derivatization methods for the HPLC-based quantitative analysis of aliphatic diamines exhibit poor sensitivity and efficiency for the monitoring of enzyme activity. In this study, a chemical derivatization method using diethyl ethoxymethylenemalonate (DEEMM) was applied to monitor lysine decarboxylase activity for the production of cadaverine by measuring the levels of intracellular and secreted lysine and cadaverine. The calibration graphs for the determination of 2,4-diaminobutyrate, 2,6-diaminopimelic acid, ornithine, arginine, lysine, 1,3-diaminopropane, putrescine dihydrochloride, cadaverine, hexamethylenediamine, and 1,7-diaminoheptane were measured by the highly sensitive method using DEEMM, and a linear relationship was observed for each dimaine compound, with limits of detection up to 0.001mM. Application of this method will be useful for the sensitive monitoring of lysine decarboxylase reactions through the detection of substrates containing amine groups and products with diamines using HPLC and a UV detector.

Acid-adapted strains of Escherichia coli K-12 obtained by experimental evolution.

Enteric bacteria encounter a wide range of pHs throughout the human intestinal tract. We conducted experimental evolution of Escherichia coli K-12 to isolate clones with increased fitness during growth under acidic conditions (pH 4.5 to 4.8). Twenty-four independent populations of E. coli K-12 W3110 were evolved in LBK medium (10 g/liter tryptone, 5 g/liter yeast extract, 7.45 g/liter KCl) buffered with homopiperazine-N,N'-bis-2-(ethanosulfonic acid) and malate at pH 4.8. At generation 730, the pH was decreased to 4.6 with HCl. By 2,000 generations, all populations had achieved higher endpoint growth than the ancestor at pH 4.6 but not at pH 7.0. All evolving populations showed a progressive loss of activity of lysine decarboxylase (CadA), a major acid stress enzyme. This finding suggests a surprising association between acid adaptation and moderation of an acid stress response. At generation 2,000, eight clones were isolated from four populations, and their genomes were sequenced. Each clone showed between three and eight missense mutations, including one in a subunit of the RNA polymerase holoenzyme (rpoB, rpoC, or rpoD). Missense mutations were found in adiY, the activator of the acid-inducible arginine decarboxylase (adiA), and in gcvP (glycine decarboxylase), a possible acid stress component. For tests of fitness relative to that of the ancestor, lacZ::kan was transduced into each strain. All acid-evolved clones showed a high fitness advantage at pH 4.6. With the cytoplasmic pH depressed by benzoate (at external pH 6.5), acid-evolved clones showed decreased fitness; thus, there was no adaptation to cytoplasmic pH depression. At pH 9.0, acid-evolved clones showed no fitness advantage. Thus, our acid-evolved clones showed a fitness increase specific to low external pH.

In vitro inhibition of lysine decarboxylase activity by organophosphate esters

Organophosphate esters (OPEs), a major group of organophosphorus flame retardants, are regarded as emerging environmental contaminants of health concern. Amino acid decarboxylases catalyze the conversion of amino acids into polyamines that are essential for cell proliferation, hypertrophy and tissue growth. In this paper, inhibitory effect of twelve OPEs with aromatic, alkyl or chlorinated alkyl substituents on the activity of lysine decarboxylase (LDC) was assessed quantitatively with an economic and label-free fluorescence sensor and cell assay. The sensor comprises a macrocyclic host (cucurbit[7]uril) and a fluorescent dye (acridine orange) reporter. The twelve OPEs were found to vary in their capacity to inhibit LDC activity. Alkyl group substituted OPEs had no inhibitory effect. By contrast, six OPEs substituted with aromatic or chlorinated alkyl groups inhibited LDC activity significantly with IC50 ranging from 1.32μM to 9.07μM. Among them, the inhibitory effect of tri-m-cresyl phosphate (TCrP) was even more effective as an inhibitor than guanosine 5′-diphosphate-3′-diphosphate (ppGpp) (1.60μM), an LDC natural inhibitor in vivo. Moreover, at non-cytotoxic concentrations, these six OPEs showed perceptible inhibitory effects on LDC activity in PC12 living cells, and led to a marked loss in the cadaverine content. Molecular docking analysis of the LDC/OPE complexes revealed that different binding modes contribute to the difference in their inhibitory effect. Our finding suggested that LDC, as a new potential biological target of OPEs, might be implicated in toxicological and pathogenic mechanism of OPEs.

Cellular target recognition of perfluoroalkyl acids: In vitro evaluation of inhibitory effects on lysine decarboxylase

Perfluoroalkyl acids (PFAAs) have been shown to bind with hepatic peroxisome proliferator receptor α, estrogen receptors and human serum albumin and subsequently cause some toxic effects. Lysine decarboxylase (LDC) plays an important role in cell growth and developmental processes. In this study, the inhibitory effect of 16 PFAAs, including 13 perfluorinated carboxylic acids (PFCAs) and 3 perfluorinated sulfonic acids (PFSAs), on lysine decarboxylase (LDC) activity was investigated. The inhibition constants obtained in fluorescence enzyme assays fall in the range of 2.960μM to 290.8μM for targeted PFCAs, and 41.22μM to 67.44μM for targeted PFSAs. The inhibitory effect of PFCAs increased significantly with carbon chain (7–18 carbons), whereas the short chain PFCAs (less than 7 carbons) did not show any effect. Circular dichroism results showed that PFAA binding induced significant protein secondary structural changes. Molecular docking revealed that the inhibitory effect could be rationalized well by the cleft binding mode as well as the size, substituent group and hydrophobic characteristics of the PFAAs. At non-cytotoxic concentrations, three selected PFAAs inhibited LDC activity in HepG2 cells, and subsequently resulted in the decreased cadaverine level in the exposed cells, suggesting that LDC may be a possible target of PFAAs for their in vivo toxic effects.

The effect of a mealybug infestation on the activity of amino acid decarboxylases in orchid leaves

Changes in the activity of lysine decarboxylase (LDC), tyrosine decarboxylase (TyDC), and ornithine decarboxylase (ODC) within orchid (Phalaenopsis × hybridum ‘Innocence’) leaves, infested by two mealybug species: Pseudococcus longispinus (Targ. Tozz.) and Pseudococcus maritimus (Ehrh.) were quantified. The pattern of changes was dependent on the insect species and duration of infestation. P. longispinus feeding increased LDC and TyDC activity after one week during the total period of observations. This species inhibited ODC activity after one week but increased later. P. maritimus decreased LDC activity in orchid leaves at all studied terms. TyDC action also went up during the first week of the infestation and was reduced after two weeks, while ODC was decreased after one day and induced later. The mechanism for the participation of analysed amino acid decarboxylases in local and/or systemic steps of orchid responses to mealybug infestation is discussed.

Participation of amino acid decarboxylases in biochemical interactions between triticale (Triticosecale; Poaceae) and bird cherry-oat aphid (Rhopalosiphum padi; Aphididae)

The roles of ornithine decarboxylase, lysine decarboxylase and tyrosine decarboxylase in biochemical interactions of two cultivars of winter triticale (Triticosecale), Tornado and Witon, and bird cherry-oat aphid (Rhopalosiphum padi L.) were determined. Results showed the resistant Witon had higher lysine decarboxylase activity than the susceptible Tornado. There was a significant negative correlation between the density of R. padi populations and lysine decarboxylase activity. Such correlations did not occur for the other decarboxylases. Aphid feeding induced a decrease of lysine decarboxylase activity within both cultivars after one week of infestation and increased its activity after two weeks in the moderately resistant Witon. Ornithine decarboxylase activity was induced in tissues of the susceptible Tornado and inhibited in Witon after two weeks of infestation. Aphid infestations did not change tyrosine decarboxylase activity in Witon, whereas in Tornado it decreased in activity after one day of aphid feeding and then increased after two weeks. It was concluded that of the three enzymes studied, lysine decarboxylase was the most important in the response of winter triticale to infestation by R. padi.

Burkholderia pseudomultivorans sp. nov., a novel Burkholderia cepacia complex species from human respiratory samples and the rhizosphere

Eleven Burkholderia cepacia-like isolates of human clinical and environmental origin were examined by a polyphasic approach including recA and 16S rRNA sequence analysis, multilocus sequence analysis (MLSA), DNA base content determination, fatty acid methyl ester analysis, and biochemical characterization. The results of this study demonstrate that these isolates represent a novel species within the B. cepacia complex (Bcc) for which we propose the name Burkholderia pseudomultivorans. The type strain is strain LMG 26883T (=CCUG 62895T). B. pseudomultivorans can be differentiated from other Bcc species by recA gene sequence analysis, MLSA, and several biochemical tests including growth at 42°C, acidification of sucrose and adonitol, lysine decarboxylase and β-galactosidase activity, and esculin hydrolysis.

Oceanospirillum nioense sp. nov., a marine bacterium isolated from sediment sample of Palk bay, India

A novel Gram-negative, spiral shaped, motile bacterium, designated strain NIO-S6(T), was isolated from a sediment sample collected from Off-shore Rameswaram, Tamilnadu, India. Strain NIO-S6(T) was found to be positive for oxidase, DNase and lysine decarboxylase activities and negative for catalase, gelatinase, lipase, ornithine decarboxylase, nitrate reductase, aesculinase, amylase and urease activities. The fatty acids were determined to be dominated by C10:0 3OH, C16:0, C16:1 and C18:1. Strain NIO-S6(T) contains Q-8 as the major respiratory quinone. The DNA G+C content of the strain NIO-S6(T) was determined to be 49.5 ± 0.6 mol %. Phylogenetic analysis based on 16S rRNA gene sequence of strain NIO-S6(T) indicated Oceanospirillum linum and Oceanospirillum maris of the family Oceanospirillaceae (phylum Proteobacteria) are the closest related species with sequence similarities of 98.4 and 97.8 % respectively. Other members of the family showed sequence similarities <96.4 %. However, DNA-DNA hybridization with Oceanospirillum linum LMG 5214(T) and Oceanospirillum maris LMG 5213(T) showed a relatedness of 31.5 and 46.9 % with respect to strain NIO-S6(T). Based on the phenotypic characteristics and on phylogenetic inference, strain NIO-S6(T) is proposed as a novel species of the genus Oceanospirillum as Oceanospirillum nioense sp. nov. and the type strain is NIO-S6(T) (=MTCC 11154(T) = KCTC 32008(T)).

Engineering Escherichia coli for renewable production of the 5‐carbon polyamide building‐blocks 5‐aminovalerate and glutarate

Through metabolic pathway engineering, novel microbial biocatalysts can be engineered to convert renewable resources into useful chemicals, including monomer building-blocks for bioplastics production. Here we describe the systematic engineering of Escherichia coli to produce, as individual products, two 5-carbon polyamide building blocks, namely 5-aminovalerate (AMV) and glutarate. The modular pathways were derived using "parts" from the natural lysine degradation pathway of Pseudomonas putida KT2440. Endogenous over-production of the required precursor, lysine, was first achieved through metabolic deregulation of its biosynthesis pathway by introducing feedback resistant mutants of aspartate kinase III and dihydrodipicolinate synthase. Further disruption of native lysine decarboxylase activity (by deleting cadA and ldcC) limited cadaverine by-product formation, enabling lysine production to 2.25 g/L at a glucose yield of 138 mmol/mol (18% of theoretical). Co-expression of lysine monooxygenase and 5-aminovaleramide amidohydrolase (encoded by davBA) then resulted in the production of 0.86 g/L AMV in 48 h. Finally, the additional co-expression of glutaric semialdehyde dehydrogenase and 5-aminovalerate aminotransferase (encoded by davDT) led to the production of 0.82 g/L glutarate under the same conditions. At this output, yields on glucose were 71 and 68 mmol/mol for AMV and glutarate (9.5 and 9.1% of theoretical), respectively. These findings further expand the number and diversity of polyamide monomers that can be derived directly from renewable resources.

EFFECT OF PEA APHID INFESTATION ON ACTIVITY OF AMINO ACID DECARBOXYLASES IN PEA TISSUES

The study examined changes in lysine decarboxylase (LDC), ornithine decarboxylase (ODC) and tyrosine decarboxylase (TyDC) activity in tissues of pea (Pisum sativum L.) infested by the pea aphid (Acyrthosiphon pisum Harris). The aphid induced increased ODC activity after one day and at two weeks. The effect was clearly systemic. TyDC activity increased after one day and at one week at feeding sites (aerial parts), while LDC activity increased only after one day of infestation and then decreased. Attack by aphids also affected enzyme activity in root tissues not directly damaged by the herbivores. The mechanisms of the response induced by pea aphid infestation in pea are discussed.

Marinilabilia nitratireducens sp. nov., a lipolytic bacterium of the family Marinilabiliaceae isolated from marine solar saltern

A Gram-negative, rod shaped, motile bacterium, was isolated from a marine solar saltern sample collected from Kakinada, India. Strain AK2(T) was determined to be positive for nitrate reduction, catalase, Ala-Phe-Pro-arylamidase, β-galactosidase, β-N-acetylglucosaminidase, β-glucosidase, β-xylosidase, α-glucosidase, α-galactosidase and phosphatase activities, hydrolysis of aesculin, Tween 20/40/60/80 and urea. It was determined to be negative for oxidase, lysine decarboxylase and ornithine decarboxylase activities and could not hydrolyze agar, casein, gelatin and starch. The predominant fatty acids were identified as iso-C(15:0) (28.2 %), anteiso-C(15:0) (23.2 %), iso-C(13:0) (19.9 %) and iso-C(15:0) 3-OH (13.9 %). Strain AK2(T) was found to contain menaquinone with seven isoprene units (MK-7) as the sole respiratory quinone and phosphatidylethanolamine, one unidentified phospholipid and three unidentified lipids as polar lipids. The 16S rRNA gene sequence analysis indicated the strain AK2(T) as a member of the genus Marinilabilia and is closely related to Marinilabilia salmonicolor with pair-wise sequence similarity of 98.2 %. Phylogenetic analysis of 16S rRNA gene revealed that the strain AK2(T) clustered with M. salmonicolor. However, DNA-DNA hybridization with M. salmonicolor JCM 21150(T) showed a relatedness of 48 ± 0.5 % with respect to strain AK2(T). The DNA G+C content of the strain was determined to be 40.2 mol%. Based on the phenotypic characteristics and phylogenetic inference, it is proposed that the strain AK2(T) represents a novel species of the genus Marinilabilia, for which the name Marinilabilia nitratireducens sp. nov. is proposed. The type strain of M. nitratireducens sp. nov. is AK2(T) (= MTCC 11402(T) = JCM 17679(T)).

Evolution of a novel lysine decarboxylase in siderophore biosynthesis

Structural backbones of iron-scavenging siderophore molecules include polyamines 1,3-diaminopropane and 1,5-diaminopentane (cadaverine). For the cadaverine-based desferroxiamine E siderophore in Streptomyces coelicolor, the corresponding biosynthetic gene cluster contains an ORF encoded by desA that was suspected of producing the cadaverine (decarboxylated lysine) backbone. However, desA encodes an l-2,4-diaminobutyrate decarboxylase (DABA DC) homologue and not any known form of lysine decarboxylase (LDC). The only known function of DABA DC is, together with l-2,4-aminobutyrate aminotransferase (DABA AT), to synthesize 1,3-diaminopropane. We show here that S. coelicolor desA encodes a novel LDC and we hypothesized that DABA DC homologues present in siderophore biosynthetic clusters in the absence of DABA AT ORFs would be novel LDCs. We confirmed this by correctly predicting the LDC activity of a DABA DC homologue from a Yersinia pestis siderophore biosynthetic pathway. The corollary was confirmed for a DABA DC homologue, adjacent to a DABA AT ORF in a siderophore pathway in the cyanobacterium Anabaena variabilis, which was shown to be a bona fide DABA DC. These findings enable prediction of whether a siderophore pathway will utilize 1,3-diaminopropane or cadaverine, and suggest that the majority of bacteria use DABA AT and DABA DC for siderophore, rather than norspermidine/polyamine biosynthesis.