Stereochemistry of lysine 2,3-aminomutase isolated from Clostridium subterminale strain SB4

Aberhart, D. John; Gould, Stephen J.; Lin, Horng-Jau; Thiruvengadam, T. K.

doi:10.1021/ja00354a046

Cited by 62 publications

(32 citation statements)

References 9 publications

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“…LAM catalyzes the interconversion of L-␣-lysine and L-␤-lysine, which proceeds by migration of the amino group from C2 to C3 concomitant with cross-migration of the 3-pro-R hydrogen of L-␣-lysine to the 2-pro-R position of L-␤-lysine (2). Hydrogen transfer takes place without exchange with solvent protons.…”

mentioning

confidence: 99%

The x-ray crystal structure of lysine-2,3-aminomutase from Clostridium subterminale

Lepore

Ruzicka²,

Frey³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

155

184

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pyridoxal phosphate ͉ radical mechanism ͉ S-adenosylmethionine L ysine-2,3-aminomutase (LAM) was first purified and characterized from Clostridium subterminale SB4 in connection with studies of lysine metabolism in Clostridia (1). LAM catalyzes the interconversion of L-␣-lysine and L-␤-lysine, which proceeds by migration of the amino group from C2 to C3 concomitant with cross-migration of the 3-pro-R hydrogen of L-␣-lysine to the 2-pro-R position of L-␤-lysine (2). Hydrogen transfer takes place without exchange with solvent protons. Enzymatic isomerization reactions of this type typically require adenosylcobalamin as a coenzyme, and the reactions proceed by radical mechanisms initiated by homolytic cleavage of the Co-C5Ј bond to generate the 5Ј-deoxyadenosyl radical. However, LAM does not require a vitamin B 12 coenzyme but instead requires a [4Fe-4S] cluster, S-adenosyl-L-methionine (SAM), and pyridoxal-5Ј-phosphate (PLP) as coenzymes (3,4).A mechanistic feature in the action of LAM, shared in common with adenosylcobalamin-dependent enzymes, is the participation of the 5Ј-deoxyadenosyl radical, which initiates free radical formation. However, in the reaction of LAM, this radical initiator arises from a reversible chemical reaction between SAM and the [4Fe-4S] 1ϩ cluster, leading to the homolytic scission of the C5Ј-S bond in SAM (4, 5). Spectroscopic results indicate that homolysis takes place by reductive cleavage of SAM through electron transfer from the [4Fe-4S] 1ϩ cluster, leading to the [4Fe-4S] 2ϩ cluster and the 5Ј-deoxyadenosyl radical (6, 7). LAM is a member of the radical-SAM superfamily, which is characterized in part by the cysteine motif CxxxCxxC in the amino acid sequences of family members (8). The three cysteine residues in the motif donate three sulfhydryl ligands to three iron atoms in the [4Fe-4S] cluster, leaving a unique iron that accepts ligands from SAM. The actions of these enzymes entail the transient formation of the 5Ј-deoxyadenosyl radical as an enzyme-bound intermediate through the reaction of SAM with the iron-sulfur cluster (4).Spectroscopic studies laid a groundwork for understanding the mechanism by which radical-SAM enzymes catalyze the reductive cleavage of SAM to methionine and the 5Ј-deoxyadenosyl radical. Selenium x-ray absorption spectroscopy of LAM activated by Se-adenosyl-L-selenomethionine (SeSAM) or in complex with Lselenomethionine revealed a direct ligation of selenium with iron (6). Electron nuclear double resonance experiments demonstrating N͞O chelation of the methionyl carboxylate and amino groups of SAM with the unique iron sites of the [4Fe-4S] clusters in pyruvate formate lyase activase and LAM characterized the ligation in the SAM͞[4Fe-4S] complex (7, 9). Taken together, these results suggested an inner sphere pathway for electron transfer in the homolytic scission of the C5Ј-S bond in SAM (7,9). A mechanism such as that shown in Scheme 1 accounts for the reversible cleavage of SAM at the active site of LAM (7). A different mechanism has been proposed for the...

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mentioning

confidence: 99%

The x-ray crystal structure of lysine-2,3-aminomutase from Clostridium subterminale

Lepore

Ruzicka²,

Frey³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

155

184

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“…These mutases cleave and form bonds during catalysis either via a radical-dependent homolytic mechanism or via an ion-dependent heterolytic mechanism. The former reaction requires pyridoxal phosphate and either cobalamin (30,31) or S-adenosylmethionine (32,33) as cofactors, whereas the latter reaction employs either exogenous pyridoxal phosphate (34) or ATP (20,35) or initiates mutase activity by the action of an internal electronegative MIO moiety formed autocatalytically from a conserved active site motif (Asp-Ser-Gly) and requires no external cofactors (21) (Fig. 1B).…”

Section: Resultsmentioning

confidence: 99%

Cloning, Heterologous Expression, and Characterization of a Phenylalanine Aminomutase Involved in Taxol Biosynthesis

Walker

Klettke

Akiyama

et al. 2004

Journal of Biological Chemistry

128

140

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Biosynthesis of the N-benzoyl phenylisoserinoyl side chain of the anticancer drug Taxol starts with the conversion of 2S-␣-phenylalanine to 3R-␤-phenylalanine by phenylalanine aminomutase (PAM). A gene cloning approach was based on the assumption that PAM would resemble the well known plant enzyme phenylalanine ammonia lyase. A phenylalanine ammonia lyase-like sequence acquired from a Taxus cuspidata cDNA library was expressed functionally in Escherichia coli and confirmed as the target aminomutase that is virtually identical to the recombinant enzyme and clone from Taxus The final stages of Taxol biosynthesis (see Fig. 1A) in yew species involve the assembly and attachment to C-13 of the taxane core of the N-benzoyl phenylisoserinoyl side chain, which is an important pharmacophoric descriptor of this anticancer drug (1, 2). In the current practice of Taxol production, this side chain is attached by chemical semisynthesis to baccatin III, which is derived from 10-deacetylbaccatin III, a Taxus (yew) metabolite that is much more readily available than Taxol itself (3-5). In the biosynthetic pathway, five steps are involved in the construction of the side chain. The first step is considered to be the conversion of 2S-␣-phenylalanine to 3R-␤-phenylalanine by an aminomutase that catalyzes an intramolecular migration of the amino group and a partial internal transfer of the pro-3S hydrogen (6, 7). This step is seemingly followed by the ligase-mediated activation to the corresponding CoA ester and then the transfer of ␤-phenylalanoyl to the C-13 hydroxyl of baccatin III. The resulting intermediate (designated ␤-phenylalanoyl baccatin III or N-debenzoyl-2Ј-deoxytaxol) then likely undergoes cytochrome P450-mediated hydroxylation at the side chain 2Ј-position to generate the isoserinoyl moiety and final N-benzoylation of this side chain (8) to complete the biosynthesis of Taxol. cDNAs encoding the two transferases involved in C-13 side chain assembly have been described previously (8,9).The relative abundance of ␤-phenylalanine and side chaindeficient late pathway metabolites such as baccatin III and 10-deacetylbaccatin III in vivo (10) suggests that either the CoA ligase for ␤-phenylalanine or the CoA ester-dependent ␤-phenylalanoyltransferase (9), both of which function downstream of the aminomutase, may be rate limiting in side chain assembly and, thus, in Taxol biosynthesis. Because the phenylalanine aminomutase (PAM) 1 catalyzes the first step of the side chain assembly process and shares its primary metabolite substrate, phenylalanine, with several competing, non-taxoid phenylpropanoid pathway enzymes in plants (11-13), it is therefore an important target for genetic engineering in yew or derived cell cultures to increase Taxol production yields. PAM is also of interest enzymologically because the reaction that is catalyzed is unusual, and, in addition to the adenosylcobalamin-dependent leucine 2,3-aminomutase from Andrographis paniculata and potato tubers (14 -16), it is the only other aminomutase of plant origin d...

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“…The hexameric enzyme with a molecular weight of 285 kDa requires SAM and PLP as cofactors and the presence of iron ions [51,52]. Incubation experiments of cell free extracts of C. subterminale SB4 with (2RS)-[3-13 C,2-15 N]lysine revealed that the amino group is shifted in an intramolecular reaction from the (2S)-position to the (3S)-position in (S)-b-lysine [53]. Similar feeding experiments with (2RS,3R)-[3-2 H] lysine and (2RS,3S)-[3-2 H]lysine demonstrated that the pro-(3R) hydrogen of L-lysine (40) migrates to the pro-(2R) position in (S)-b-lysine (21), while the pro-(3S) hydrogen remains at C-3 (Scheme 4.5) [53].…”

Section: 22mentioning

confidence: 99%

β‐Amino Acid Biosynthesis

Spiteller

2009

Amino Acids, Peptides and Proteins in Organic Chemistry

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Stereochemistry of lysine 2,3-aminomutase isolated from Clostridium subterminale strain SB4

Cited by 62 publications

References 9 publications

The x-ray crystal structure of lysine-2,3-aminomutase from Clostridium subterminale

The x-ray crystal structure of lysine-2,3-aminomutase from Clostridium subterminale

Cloning, Heterologous Expression, and Characterization of a Phenylalanine Aminomutase Involved in Taxol Biosynthesis

β‐Amino Acid Biosynthesis

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