The Corynebacterium glutamicum aecD gene encodes a C-S lyase with alpha, beta-elimination activity that degrades aminoethylcysteine

Rossol, I; Pühler, Alfred

doi:10.1128/jb.174.9.2968-2977.1992

Cited by 46 publications

(33 citation statements)

References 59 publications

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“…Table 4 provides a complete overview of the ATs plus some PLP-containing proteins as results from the various approaches based on genome information for C. glutamicum and functional studies. The PLP-containing MetC (AecD) is not an AT, but it has ␤-lyase activity toward cystathionine (27) or the unnatural amino acid S-(2-aminoethyl)-D,L-cysteine (35). We also did not find any AT activity with NCgl2491, which is adjacent in the genome to a putative T-protein of a glycine cleavage system.…”

Section: Vol 187 2005 Activities Of Aminotransferases In Corynebactmentioning

confidence: 72%

Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

et al. 2005

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Twenty putative aminotransferase (AT) proteins of Corynebacterium glutamicum, or rather pyridoxal-5-phosphate (PLP)-dependent enzymes, were isolated and assayed among others with L-glutamate, L-aspartate, and L-alanine as amino donors and a number of 2-oxo-acids as amino acceptors. One outstanding AT identified is AlaT, which has a broad amino donor specificity utilizing (in the order of preference) L-glutamate > 2-aminobutyrate > L-aspartate with pyruvate as acceptor. Another AT is AvtA, which utilizes L-alanine to aminate 2-oxo-isovalerate, the L-valine precursor, and 2-oxo-butyrate. A second AT active with the L-valine precursor and that of the other two branched-chain amino acids, too, is IlvE, and both enzyme activities overlap partially in vivo, as demonstrated by the analysis of deletion mutants. Also identified was AroT, the aromatic AT, and this and IlvE were shown to have comparable activities with phenylpyruvate, thus demonstrating the relevance of both ATs for L-phenylalanine synthesis. We also assessed the activity of two PLPcontaining cysteine desulfurases, supplying a persulfide intermediate. One of them is SufS, which assists in the sulfur transfer pathway for the Fe-S cluster assembly. Together with the identification of further ATs and the additional analysis of deletion mutants, this results in an overview of the ATs within an organism that may not have been achieved thus far.

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Section: Vol 187 2005 Activities Of Aminotransferases In Corynebactmentioning

confidence: 72%

Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

et al. 2005

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“…With the others, a correlation to L-serine is probably less apparent (see Discussion). Most interestingly, the cystathionine ␤-lyase mRNA level (metC) is increased 2.4-fold, and the respective enzyme of L-methionine synthesis (24), catalyzing a ␤-elimination reaction, has been reported to have a broad substrate specificity in C. glutamicum and in E. coli, also reacting with L-cysteine, which is structurally related to L-serine (1,45,59).…”

Section: Resultsmentioning

confidence: 99%

Cometabolism of a Nongrowth Substrate:l-Serine Utilization byCorynebacterium glutamicum

Netzer

Peters‐Wendisch

Eggeling

et al. 2004

Appl Environ Microbiol

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C-labeled L-serine and analysis of cellularly derived metabolites by nuclear magnetic resonance spectroscopy revealed that the carbon skeleton of L-serine is mainly converted to pyruvate-derived metabolites such as L-alanine. The sdaA gene was identified in the genome of C. glutamicum, and overexpression of sdaA resulted in (i) functional L-serine dehydratase (L-SerDH) activity, and therefore conversion of L-serine to pyruvate, and (ii) growth of the recombinant strain on L-serine as the single substrate. In contrast, deletion of sdaA decreased the L-serine cometabolism rate with glucose by 47% but still resulted in degradation of L-serine to pyruvate. Cystathionine ␤-lyase was additionally found to convert L-serine to pyruvate, and the respective metC gene was induced 2.4-fold under high internal L-serine concentrations. Upon sdaA overexpression, the growth rate on glucose is reduced 36% from that of the wild type, illustrating that even with glucose as a single substrate, intracellular L-serine conversion to pyruvate might occur, although probably the weak affinity of L-SerDH (apparent K m , 11 mM) prevents substantial L-serine degradation.Cometabolism is often observed for xenobiotic compounds which do not enable growth as a single carbon-and energy source (21). This is due, for example, to long degradation pathways and unnatural structures. On the other hand, microorganisms with a restricted metabolism, such as Lactococcus lactis, are dependent on cometabolism of essential natural compounds, e.g., amino acids (35). The amino acid L-serine is characterized by the fact that several organisms have the ability to introduce it into the central metabolism via pyruvate (35,2,16). Another distinguishing feature is its high cellular demand, exceeding the simple provision of L-serine for protein synthesis, since L-serine is additionally required for glycine, cysteine, tryptophan, and phospholipid synthesis as well as for 1-carbonunit generation (52). Glycine, in turn, is a precursor for purines and heme. In Corynebacterium glutamicum about 7.5% of the total carbon flux toward L-serine is utilized for these purposes (28). Prior estimates for Escherichia coli determined that as much as 15% of the carbon assimilated from glucose involves L-serine (42). Due to the high demand and its key position in the precursor supply, L-serine has to be regarded as an intermediate of the central metabolism (52).In spite of the presence of L-serine dehydratase (L-SerDH) (47) and the key position of L-serine, growth of E. coli on L-serine as a carbon source is very poor, allowing doubling times of about 60 h only (63). When the organism is additionally exposed to low concentrations of glycine, isoleucine, and threonine, growth is enhanced (36). Interestingly, during growth on tryptone broth, where a number of amino acids are present, L-serine is utilized immediately and earlier than any other amino acid (43). Taken together, L-serine is clearly a poor growth substrate for E. coli and is preferably cometabolized. Klebsiella aerogenes and ...

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“…A routine check for protein homology revealed that the deduced amino acid sequence of MalY (24) showed small but significant homology (22.5% identity) to the sequence of the AecD protein of C. glutamicum, an enzyme that, when overproduced, confers resistance to S-2-aminoethyl-L-cysteine (AEC; also called thiolysine) in this bacterium (27). AecD has been identified as a ␤C-S lyase forming ammonia and pyruvate from amino acids containing a ␤C-S linkage (27). The availability of the MalY protein in purified form allowed us to test the enzymatic activity of MalY as a ␤C-S lyase.…”

Section: Resultsmentioning

confidence: 99%

MalY of Escherichia coli is an enzyme with the activity of a beta C-S lyase (cystathionase)

et al. 1995

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The Escherichia coli maltose system consists of a number of genes whose products are involved in the uptake and metabolism of maltose and maltodextrins. MalT is the central positive gene activator of the regulon and is, together with the cyclic AMP-catabolite gene activator protein system, necessary for the expression of the maltose genes. Expression of malY, a MalT-independent gene, leads to the repression of all MalT-dependent genes. We have purified MalY to homogeneity and found it to be a pyridoxal-5-phosphate-containing enzyme with the enzymatic activity of a ␤C-S lyase (cystathionase). MalY is a monomeric protein of 42,000 to 44,000 Da. Strains expressing MalY constitutively abolish the methionine requirement of metC mutants. The enzymatic activity of MetC, the cleavage of cystathionine to homocysteine, ammonia, and pyruvate, can be catalyzed by MalY. However, the cystathionase activity is not required for the function of MalY in repressing the maltose system. By site-directed mutagenesis, we changed the conserved lysine residue at the pyridoxal phosphate binding site (position 233) of MalY to isoleucine. This abolished ␤C-S lyase activity but not the ability of the protein to repress the maltose system. Also, the overexpression of plasmid-encoded metC did not affect mal gene expression, nor did the deduced amino acid sequence of MetC show homology to that of MalY.The maltose regulon of Escherichia coli consists of two sets of genes which encode proteins involved in the uptake and metabolism of maltose and maltodextrins (␣1,4-linked D-glucose polymers) (29). Expression of the maltose genes is dependent on the presence of the inducer, maltotriose, bound to the positive regulator, MalT (23). Mutants lacking MalT function do not express any mal genes and are phenotypically Mal Ϫ , whereas malT(Con) mutations render mal gene expression independent of (or less dependent on) the inducer, maltotriose (10, 11). The expression of malT, as well as of some of the mal genes, is dependent on activation by the cyclic AMP-catabolite gene activator protein complex (9). Several observations demonstrate that the regulation of the maltose system is not as straightforward as implied above. First, there is the phenomenon of internal induction (12). Second, MalK, the ATP-consuming subunit of the maltose transport system, acts phenotypically as a repressor of the system, affecting the function of MalT (6,18,19,26). The third regulatory circuit affecting mal gene expression is derived from the malI malX malY gene cluster. malI was discovered as a mutation which strongly reduced the high and constitutive expression of a malK-lacZ fusion (14). Molecular analysis of malI (25) and its adjacent genes revealed that malI encodes a typical repressor protein, analogous to LacI and GalR, which prevents the expression of the adjacent and divergently oriented malX malY operon. The gene product of malX is a protein homologous to the enzyme II Glc of the phosphotransferase system. malY encodes a protein with sequence homology, including the ch...

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The Corynebacterium glutamicum aecD gene encodes a C-S lyase with alpha, beta-elimination activity that degrades aminoethylcysteine

Cited by 46 publications

References 59 publications

Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

Functional Analysis of All Aminotransferase Proteins Inferred from the Genome Sequence ofCorynebacterium glutamicum

Cometabolism of a Nongrowth Substrate:l-Serine Utilization byCorynebacterium glutamicum

MalY of Escherichia coli is an enzyme with the activity of a beta C-S lyase (cystathionase)

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