Experimental murine hyalohyphomycosis with soil-derived isolates of Fusarium solani

Two strains of soil-borne Fusarium solani, both characterized for their ability to produce cyclosporin A and C, were examined for their pathogenicity in severe combined immunodeficiency (SCID) and BALB/c male mice. Intravenous (i.v.) infections with F. solani conidia were performed. No mortality was observed after infection with 0.3-1.6 x 10(7) cfu per mouse in SCID and BALB/c mice. When mice were infected with 0.8-1.5 x 10(6) cfu per mouse and 2 days later with 1.2-1.9 x 10(6) cfu per mouse, 28.6-85.7% survival occurred over a 25-day period, depending on the F. solani strain and the inbred mouse line used. Death was preceded by renal insufficiency affecting both kidneys. Furthermore, i.v. injection with heat-killed conidia followed 2 days later by injecting viable conidia resulted in renal infection in both breeds of mice. F. solani isolated from infected organs was more virulent than the original isolate, and 3/8 (37.5%) of BALB/c and 4/7 (57.1%) of SCID mice died after receiving a single dose. Dissemination to the brain was found only in SCID mice, but torticollis was observed in both mouse breeds. Soil-borne F. solani isolates possess poor pathogenic potential for mice, but either two successive infective doses or a primary injection with heat-killed conidia followed by a single infective dose breaks through host defenses in normal and immunoincompetent mice. Mouse passage increased the pathogenicity of two soil-derived F. solani strains.

Structure and localization of cyclosporin synthetase, the key enzyme of cyclosporin biosynthesis in Tolypocladium inflatum

The electron microscopic image of native cyclosporin synthetase molecules showed large globular complexes of 25 nm in diameter, built up by smaller interconnected units. Compartmentation of cyclosporin synthetase and the functionally interconnected D-alanine racemase was revealed after sucrose density gradient centrifugation of subcellular fractions and immunoelectron microscopy. A considerable proportion of cyclosporin synthetase and D-alanine racemase was detected at the vacuolar membrane. The product cyclosporin was localized in the fungal vacuole.

Applications of peptide synthetases in the synthesis of peptide analogues

Enzymatically formed peptides show positional variations as well as highly conserved amino acids. In the cases of gramicidin S, tyrocidine, linear gramicidins, enniatins, echinocandins and viridogrisein in vivo and in vitro studies indicate substrate selection at the level of amino acid activation as a major control step. Evidence for proof-reading steps beyond activation has been obtained in penicillin and cyclosporin biosynthesis. Activated substrate analogues may promote the formation of side products such as dipeptides and cyclodipeptides. Modifications of intermediates, such as N-methylation, influence the rates of peptide synthesis. These control steps pose limitations for the application of such enzyme systems in the production of peptide libraries. They may originate from a target oriented evolution of these synthetases.

Cyclosporin C is the main antifungal compound produced by Acremonium luzulae

A strain of Acremonium luzulae (Fuckel) W. Gams was selected in screening new microorganisms for biological control of fruit postharvest diseases, especially gray and blue mold diseases on apples and strawberries. This strain manifests a very strong activity against a large number of phytopathogenic fungi. In this work, the product responsible for this antifungal activity was isolated from modified Sabouraud dextrose broth cultures of A. luzulae. It was purified to homogeneity by reverse-phase column chromatography. On the basis of UV, infrared, and 1H and 13C nuclear magnetic resonance spectra, mass spectral analysis, and the amino acid composition of the acid hydrolysates, the antibiotic was determined to be cyclosporin C. Cyclosporin C showed a broad-spectrum activity against filamentous phytopathogenic fungi but no activity against bacteria or yeasts. Its antifungal activity is only fungistatic. In contrast to Tolypocladium inflatum, another cyclosporin-producing strain, A. luzulae, did not produce additional cyclosporins. This was confirmed by in vivo-directed biosynthesis.

A unique repeated DNA sequence in the cyclosporin-producing strain of Tolypocladium inflatum (ATCC 34921)

Recombinant lambda clones containing repeated DNA sequences were isolated from the cyclosporin A-producing fungus Tolypocladium inflatum (ATCC 34921) by differential hybridization with total fungal DNA and rDNA probes. From this survey 1% of the lambda clones appeared to contain repeated sequences. Subsequent analysis led to the identification of a dispersed repetitive DNA element. It was named CPA element (cyclosporin production associated) and appears to be strain specific, since it is absent from other related strains or fungi. Hybridization with chromosomal restriction fragments indicates an equal distribution of the CPA element in the genome. The copy number was estimated to be between 20 and 30 per haploid genome. Sequence analysis of a 0.9-kb XhoI fragment from three copies of the CPA element revealed strong conservation of this sequence among all copies. A 200-bp region exhibits similarities to a repeated sequence from Zea diploperennis. The use of this DNA sequence as a molecular marker for identification of this cyclosporin-producing strain ATCC 34921 is discussed as is the relevance of repeated DNA sequences for rearrangements of fungal karyotypes.

Reversal of multidrug resistance by novel cyclosporin A analogues and the cyclopeptolide SDZ 214-103 biosynthesized in vitro

It was shown that cyclopeptolide SDZ 214-103 (10 microM) is more active in rhodamine-123 accumulation in actinomycin-D-resistant human lymphoma cells CCRF/ACTD400 than cyclosporin A (10 microM), but equipotent in the doxorubicin-resistant Friend erythroleukemia cell line F4-6/ADR. In F4-6/ADR cells, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay showed comparable cytotoxic effects of doxorubicin at various concentrations in the presence of SDZ 214-103 and cyclosporin A. For the other novel cyclosporin A analogues minor multidrug-resistance-modulating potency was demonstrated. At equipotent modulating doses of verapamil (10 microM) and cyclosporin A (10 microM) in the MTT assay regarding doxorubicin cytotoxicity, cyclosporin A was efficient in the rhodamine-123-uptake assay while verapamil was not active when identical incubation times were used.

In vitro biosynthesis of ring-extended cyclosporins

Cyclosporin synthetase, a multifunctional polypeptide, catalyses the biosynthesis of the set of natural cyclosporins. We report that this enzyme is also capable of introducing a beta-alanine into position 7 or 8 of the ring instead of the alpha-alanines present at these positions in cyclosporin A. This leads to 34-membered rings in contrast to the 33-membered ring of the cyclo-undecapeptide cyclosporin A. Both [beta Ala7]CyA and [beta Ala8]CyA show immunosuppressive activity. The cyclosporin synthetase-related enzyme peptolide SDZ 214-103 synthetase, on the other hand, does not incorporate either beta-alanine into position 7 or beta-hydroxy acids into position 8, confirming the previously described higher substrate specificity of this enzyme compared with cyclosporin synthetase [Lawen and Traber (1993) J. Biol. Chem. 268, 20452-20465].

Substrate specificities of cyclosporin synthetase and peptolide SDZ 214-103 synthetase. Comparison of the substrate specificities of the related multifunctional polypeptides

The recently discovered multifunctional polypeptide cyclosporin synthetase is capable of synthesizing the cyclic undecapeptide cyclosporin A in a batch reaction. Substrates are the unmethylated constitutive amino acids of cyclosporin A. Exchange of one or more of these by various amino acids gives a picture of the substrate specificity of the enzyme in vitro, which is different from the known picture obtained by in vivo studies. The uncommon amino acid butenylmethylthreonine in position 1 of the cyclosporin ring can be exchanged by an unexpected large spectrum of different amino acids, showing a great flexibility of this site. Position 2, on the other hand, which shows the greatest variability in vivo, has an only slightly lower specificity in vitro. Position 3 has a very high degree of specificity; positions 4, 6, 7, 9, and 10 have marginally less. The variability of positions 5 and 11 is moderate, whereas position 8 shows only low substrate specificity in vitro. In general, most sites of SDZ 214-103 synthetase appear to be more specific than those of cyclosporin synthetase. Site 11 has nearly identical substrate specificity compared with that of cyclosporin synthetase. The D-2-hydroxy acid position (position 8) can be occupied by a large spectrum of substrates varying from D-lactic acid to D-2-hydroxyisocaproic acid. Within the limits of the present data, the addition of further functional groups to the D-2-hydroxy acid moiety are apparently not tolerated by the enzyme.

Efficient production of the cyclosporin metabolite AM1 by rabbit hepatic enzymes

We describe here conditions for the in vitro preparation of the main metabolite of cyclosporin A, namely AM1, with rabbit liver enzymes. The compound was purified and was identified by comparison with the metabolite isolated from urine of rats treated with [3H]CsA and by its Mass-Spectrometry Fast Ion Bombardment (MS-FIB) and 1HNMR spectra. The procedure is simple and with the enzyme fraction derived from one rabbit liver 3-4 mg of the pure metabolite can be obtained.

Enzymatic biosynthesis of cyclosporin A and analogues

The final assembly of the undecapeptide chain of cyclosporin A and its cyclization is accomplished in Beauveria nivea by cyclosporin synthetase. This multienzyme is the largest integrated enzyme structure so far reported. Its size has been estimated at approximately 1,400 kDa by two different methods: 1), by 3% SDS-PAGE using the related multienzymes ACV synthetase and gramicidin S synthetase 2 as references (420 and 556 kDa, respectively); and 2), by CsCl density gradient centrifugation experiments using fluorescence-labeled cyclosporin synthetase. Besides cyclosporin A and a number of cyclosporins known from fermentation studies cyclosporin synthetase is capable of synthesizing some new cyclosporins which are so far unobtainable by fermentation. So, for example the synthesis of [N-methyl-(+)-2-amino-3-hydroxy-4,4-dimethyloctanoic acid1]CyA, dihydro-CyA, [L-norvaline2,5, N-methyl-L-norvaline11]CyA, [L-allo-isoleucine5, N-methyl-L-allo-isoleucine11]CyA, [D-2-aminobutyric acid8]CyA, [beta-chloro-D-alanine8]CyA and some related compounds could be established. By using a related but different enzyme from Cylindrotrichum Bonorden, the peptolide [L-threonine2, L-leucine5,10, D-2-hydroxyisovaleric acid8]CyA could be synthesized in vitro. We were able to synthesize these cyclosporins in sufficient quantities to examine their structure by FAB mass spectroscopy and explore their immunosuppressivity. It was found that all new cyclosporins so far synthesized in the in vitro system are immunosuppressive.

Formation of cyclosporins by Tolypocladium inflatum

Submerged cultures of the low-production strain of Tolypocladium inflatum DSM 63544 formed a mixture of cyclosporins (CS) consisting of CS-A, CS-B, "CS-3" and "CS-4". Glucose, sucrose and maltose were highly favored for biomass production but provided a different physiological state necessary for CS biosynthesis. Not only the magnitude of CS production but also the proportion of individual components of the CS mixture were affected by the C source. Intensive CS synthesis was in correlation with the formation of CS-3. Lower yields of CS were accompanied by an increased proportion of CS-A in the CS complex. The best specific production of CS was achieved on the glucose medium, the highest yield of CS-A on the maltose medium. There was no remarkable relationship between the biomass formation and the intensity of CS synthesis.

In vitro biosynthesis of [Thr2,Leu5,D-Hiv8,Leu10]-cyclosporin, a cyclosporin-related peptolide, with immunosuppressive activity by a multienzyme polypeptide

A new cyclic peptolide (SDZ 214-103), which is produced by the fungus Cylindrotrichumoligospermum (Corda) BONORDEN (Dreyfuss, M. M., Schreier, M. H., Tscherter, H., and Wenger, R. (June 15, 1988) European Patent Application 0 296 123 A2) and is closely related to cyclosporin A (CyA), has as the main structural difference D-2-hydroxyisovaleric acid in ester linkage at position 8 instead of D-alanine in the cyclosporins. This peptolide exerts similar biological activities to CyA. We were able to prepare an enzyme fraction of crude extracts of the mycelium, which is capable of synthesizing the peptolide with consumption of the constitutive amino acids, D-2-hydroxyisovaleric acid, ATP, and S-adenosyl-L-methionine. The in vitro product co-chromatographs with authentic peptolide on thin layer chromatography and high performance liquid chromatography and shows similar immunosuppressive activity in vitro. The enzyme does not synthesize CyA, whereas cyclosporin synthetase does not synthesize the peptolide. Peptolide synthetase has a high molecular weight (in the same range as cyclosporin synthetase) and also does not appear to be glycosylated. The enzyme cross-reacts with antibodies directed specifically against cyclosporin synthetase.

Selective 13C-labelling of cyclosporin A

Cyclosporin A is biosynthetically labelled with 13C by growing an overproducing strain of Tolypocladium inflatum on minimal media containing either [1-13C]-, [2-13C]-, [3-13C]- or [6-13C]glucose as the only carbon source. NMR analysis of the 13C-labelled peptide showed a labelling pattern in which 13C occurs at specific sites. These can be predicted by consideration of the relevant biosynthetic pathways. Quantitation of the site-specific enrichments revealed that the 13C-label incorporation is efficient and selective. Metabolic fluxes through alternative pathways can also be estimated from these results. Isotopically labelled peptides will be a very useful tool for the study of molecular interactions with their receptors.

[Effect of the quality of fat substrate on the dynamics of fatty acid utilization during biosynthesis of cephalosporin C]

Influence of the quality of the fats used on their utilization in the process of cephalosporin C fermentation and accumulation was studied. A decrease in the level of all the fractions of the fatty acids was observed during the fermentation process. The antibiotic yield with the use of oxidized fats was lower. Treatment of the fats with gaseous nitrogen prevented their oxidation. It was supposed that the decreased yields of the antibiotic were associated with the influence of the oxidized fats on the biosynthetic processes.

Isolation and partial characterization of cyclosporin synthetase from a cyclosporin non-producing mutant of Beauveria nivea

Cyclosporin synthetase was isolated from a cyclosporin non-producing mutant of Beauveria nivea, strain YP 582. The enzyme has a molecular mass in the range of active cyclosporin synthetase and also contains 4'-phosphopantetheine as a prosthetic group. It is able to activate all constituent amino acids of cyclosporin A as thioesters and to carry out specific N-methylation reactions. Overall synthesis of the undecapeptide cyclosporin A in the presence of all necessary substrates was not observed, but the formation of the diketopiperazine cyclo-(D-alanyl-N-methyl-leucyl). This diketopiperazine represents a partial sequence of the cyclosporin molecule. It could be detected in the mycelium of the non-producing strain, whereas mycelium of the producing strain 7939/45 did not contain this compound. The results suggest that the inability of this mutant to produce cyclosporin A is caused by a mutation of the polypeptide chain of cyclosporin synthetase.

[High-molecular polyphosphates and pyrophosphate in cyclosporin- producing Tolypocladium sp. and their role in the processes of growth and antibiotic synthesis]

The contents of high-energy phosphorous compounds, i.e. three fractions of polyphosphates, pyrophosphate, and ATP were determined in isogenic strains of Tolypocladium sp. differing in cyclosporine production levels. The content of polyphosphates was 1 to 2 orders of magnitude greater than that of pyrophosphate or ATP and did not depend on the strain productivity. During the period of the mycelial intensive growth and at the beginning of antibiotic synthesis, the level of polyphosphates lowered 2-3-fold and the content of pyrophosphate markedly decreased as well. The activities of polyphosphatase and pyrophosphatase during the culture growth and cyclosporine biosynthesis was higher in the highly productive strain.

Cyclosporin synthetase. The most complex peptide synthesizing multienzyme polypeptide so far described

Cyclosporin A and its homologues are synthesized by a single multifunctional enzyme from their precursor amino acids. Cyclosporin synthetase is a polypeptide chain with a molecular mass of approximately 800 kDa. In 3% polyacrylamide-sodium dodecyl sulfate gels it shows a single band of approximately 650 kDa, which appears to not be glycosylated. The enzyme could be purified to near-homogeneity in five steps. A 72-fold purification was obtained. All constitutive amino acids of cyclosporins are activated as thioesters via aminoadenylation by the same enzyme. Then N-methylation of the thioester-bound amino acids which are present in methylated form in the cyclosporin molecule takes place, whereby S-adenosyl-L-methionine serves as the methyl group donor. Methyltransferase activity is an integral entity of the enzyme; this could be shown by a photoaffinity labeling method. 4'-Phosphopantetheine is a prosthetic group of cyclosporin synthetase similar to other peptide and depsipeptide synthetases. Cyclosporin synthetase shows cross-reactions with monoclonal antibodies directed against enniatin synthetase.

Pigmented variants of Tolypocladium inflatum in relation to cyclosporin A production

We have isolated four distinct colony types of the fungus Tolypocladium inflatum, the producer of the immunosuppressive agent cyclosporin A: morphologically normal white, red, and orange colonies and morphologically diverse tiny brown colonies. In liquid cultures, white normal and brown colonies developed into yellow broths. The broth of the brown colony had a low final pH and low cyclosporin production, whereas orange and red colonies had dark brown and even black broths with higher final pH and high cyclosporin production. The specific production of cyclosporin A by the red colony was three times that of the white normal colonies.

Isolation of (4R)-4-[(E)-2-butenyl]-4-methyl-L-threonine, the characteristic structural element of cyclosporins, from a blocked mutant of Tolypocladium inflatum

By mutagenic treatment of a strain of Tolypocladium inflatum, a cyclosporin non-producing mutant was obtained which accumulated the characteristic building unit of cyclosporins, (4R)-4-[(E)-2-butenyl]-4-methyl-L-threonine (abbreviation Bmt; systematic name: (2S,3R,4R,6E)-2-amino-3-hydroxy-4-methyl-6-octenoic acid) in free form. The isolation from a culture filtrate was performed by extraction, chromatographic separation and final crystallization from methanol - water. The structure and stereochemistry of this amino acid was determined by chemical transformation and correlation to dihydro-MeBmt, with known chirality [(2S,3R,4R)-3-hydroxy-4-methyl-2-methylamino-octanoic acid], obtained by hydrolysis of dihydrocyclosporin A.

[Cyclosporin biosynthesis and dynamics of bioenergetic processes in cyclosporin-producing strain]

An attempt was made to show a correlation between definite bioenergetic parameters of the cells of the cyclosporine-producing culture and biosynthesis of cyclosporine. It was found that the three strains producing cyclosporine used in the study had an alternative cyanide-resistant pathway along with the classical cytochrome chain. In the strain forming only traces of the cyclopeptide during fermentation of the cyanide-resistant respiration constituted 60 to 80%. In the isogenic highly productive strains the cyanide-resistant respiration appeared to be markedly decreased beginning from the 1st day of fermentation and during the maximum biosynthesis of cyclosporine (on day 4 or 5 of fermentation) it reached zero. The ATP content in the cells of the highly productive strain, despite its decrease by the antibiotic biosynthesis peak, remained at a much higher level than that in the strain producing only traces of cyclosporine. A procedure for isolating functionally active mitochondria from the protoplasts was developed and a bioenergetic characterization of the mitochondria isolated from the strains with different antibiotic productions is presented.

Production of cyclosporins by Tolypocladium niveum strains

Nine strains of Tolypocladium niveum (= inflatum) were compared for their production of cyclosporins. Two of the strains, which were originally from the parental NRRL 8044 strain, were among the lower producers, while seventeen Tolypocladium strains belonging to seven other species produced no detectable cyclosporins. Variable cyclosporin production was observed initially. Once extraction and quantitation methods had been established, spore inoculum density and cultural morphology and carbon and nitrogen sources were found to be among the variables affecting cyclosporin production. Cyclosporin A was identified by cochromatography by using high-performance liquid chromatography, and cyclosporins A, B, and C were identified by gas chromatography-mass spectroscopy; all three compounds exhibited biological activity. They were routinely produced as a mixture in the ratio 7:1:2 in T. niveum UAMH 2472, which was selected on the basis of single-spore isolate total cyclosporin production and was used for most studies. This strain routinely produced total cyclosporin levels of 150 to 200 mg.liter-1 after 12 days of growth on a 2% sorbose-1% vitamin assay Casamino Acids medium.

Enhancement of cyclosporin production in a Tolypocladium inflatum strain after epichlorohydrin treatment

Following treatment of conidia of the cyclosporin producer fungus, Tolypocladium inflatum, with 0.15 M epichlorohydrin, strain M6 was isolated. The new strain exhibited a similar growth rate to the parent organism but more extensive conidiation and several-fold higher overall cyclosporin production. Strain M6 reached titres of 318 mg l-1 cyclosporin A in agar cultures, whereas in liquid medium it produced 140 mg l-1 cyclosporin A and 68 mg l-1 cyclosporin C. It also maintained a steady volumetric productivity of 0.48 mg l-1 h-1 cyclosporin A over 2 weeks of submerged cultivation in maltose-based semisynthetic medium. The new strain holds potential for improved cyclosporin production due to the superior titres and demonstrated capacity to sustain elevated production of cyclosporin for periods greater than the wild type.

Cell-free biosynthesis of new cyclosporins

An enzyme preparation, isolated from extracts of the fungus Beauveria nivea (previously designated Tolypocladium inflatum), is able to synthesize cyclosporins (Cy's) in vitro. At suboptimal temperature it was possible to yield about 50 micrograms of CyA per ml. The enzyme also produces several of the naturally occurring congeners of CyA, such as the Cy's B, C, D, G, M, O, Q, U and V and some of the analogues known to be produced by the fungus via precursor directed biosynthesis, like dihydro-CyA, [N-methyl-L-beta-cyclohexylalanine]CyA, [L-allylglycine]CyA and [D-serine]CyA. Furthermore, Cy's not obtainable by the fungus could be prepared by the enzyme system in the presence of the appropriate precursor amino acids; the synthesis of [N-methyl-(+)-2-amino-3-hydroxy-4,4-dimethyloctanoic acid]CyA, [L-norvaline, N-methyl-L-norvaline]CyA, [L-norvaline, N-methyl-L-norvaline]CyA, [L-allo-isoleucine, N-methyl-L-allo-isoleucine]CyA, [L-allo-isoleucine]CyA, [D-2-aminobutyric acid]CyA and [beta-chloro-D-alanine]CyA could be established. The immunosuppressive effects of the new derivatives are discussed.

Cyclosporins--new analogues by precursor directed biosynthesis

Cyclosporin A (ciclosporin), a potent and clinically important immunosuppressive drug (Sandimmun), represents the main component of a group of over 25 closely related, cyclic undecapeptides produced by the fungus Tolypocladium inflatum. By feeding experiments using DL-alpha-allylglycine as precursor, specific incorporation in position 2 was attained leading to [Allylgly2]cyclosporin A. Exogenously supplied L-beta-cyclohexylalanine results in the almost exclusive production of [MeCyclohexylala1]cyclosporin A (replacement of methylbutenyl-methylthreonine-1). D-Alanine in position 8 can be successfully substituted by D-serine. The new [D-Ser8] analogues of the cyclosporins A, C, D and G as well as [Allylgly2]cyclosporin A exhibit high immunosuppressive effects.

Enzymatic synthesis of cyclosporin A

An enzyme fraction, isolated from crude extracts of the fungus Tolypocladium inflatum, strain 7939/F, is able to synthesize the undecapeptide cyclosporin A. The formation of cyclosporin A was monitored by incorporation of the radiolabeled constituent amino acids of cyclosporin A or by using S-adenosyl-L-[14C-methyl] methionine. The structure of cyclosporin A, synthesized enzymatically in vitro, was confirmed by chromatographic comparison with the authentic compound and by amino acid analyses. Replacement of L-2-aminobutyric acid in the reaction mixture by L-alanine, L-threonine, L-valine, or L-norvaline yields the naturally occurring cyclosporins B, C, D, and G. Also, D-alanine could be replaced by D-serine to yield [D-Ser8]cyclosporin A.

Biosynthesis of cyclosporin A: partial purification and properties of a multifunctional enzyme from Tolypocladium inflatum

An enzyme fraction most probably involved in the biosynthesis of cyclosporin A was purified 540-fold from Tolypocladium inflatum. The enzyme was capable of forming covalent enzyme-substrate complexes and catalyzed the ATP-pyrophosphate exchange reactions dependent on the unmethylated constituent amino acids of cyclosporin A. Evidence was obtained that covalent binding of substrate amino acids occurred via thioester linkage. Furthermore, the N-methylation of thio-esterified valine, leucine, and glycine residues with S-adenosyl-L-methionine was demonstrated. De novo synthesis of cyclosporin A was not observed but the formation of the diketopiperazine cyclo-(D-Ala-MeLeu) from D-alanine and L-leucine under the consumption of ATP and S-adenosyl-L-methionine. This cyclodipeptide represents a partial sequence of cyclosporin A. Molecular mass determinations revealed the enzyme activity to be lying in the range of about 700 kDa.

Contribution to knowledge of the biosynthesis of cyclosporin A

3H- and 13C-NMR spectroscopic investigations on the structure of labeled cyclosporin A were performed after feeding of appropriate precursors. The 6 N-methyl groups and the methyl group in position 4 of the epsilon, zeta-unsaturated amino acid No. 1 (Mebmt) are introduced as intact CH3-units from methionine. Four head-to-tail acetate units are involved in the biosynthesis of the 8-carbon chain of the olefinic amino acid.