The malX malY operon of Escherichia coli encodes a novel enzyme II of the phosphotransferase system recognizing glucose and maltose and an enzyme abolishing the endogenous induction of the maltose system

Reidl, Joachim; Boos, Winfried

doi:10.1128/jb.173.15.4862-4876.1991

Cited by 96 publications

(88 citation statements)

References 79 publications

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“…Similarity of the malY gene product, with aminotransferases has been suggested previously (Reidl and Boos, 1991); it is confirmed here in a quantitative manner. The malY protein appears to fulfil some regulatory function in metabolism (Reidl and Boos, 1991) while the other three gene products are essential components in important metabolic pathways in bacteria, i.e. cobalamin synthesis, nitrogen fixation and synthesis of p-aminobenzoic acid.…”

supporting

confidence: 74%

Homology of pyridoxal‐5′‐phosphate‐dependent aminotransferases with the cobC (cobalamin synthesis), nifS (nitrogen fixation), pabC (p‐aminobenzoate synthesis) and malY (abolishing endogenous induction of the maltose system) gene products

Mehta

Christen

1993

European Journal of Biochemistry

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Bacterial deletion mutants have indicated that the gene products of cobC, nifS, pabC and malY participate in important metabolic pathways, i.e. cobalamin synthesis, nitrogen fixation, synthesis of p‐aminobenzoate and the regulation of the maltose system, respectively. However, the proteins themselves and their specific functions have not yet been identified. In the course of our studies on the evolutionary relationships among aminotransferases, we have found that the above gene products are homologous to aminotransferases. Profile analysis [Gribskov, M., Lüthy, R. & Eisenberg, D. (1990) Methods Enzymol. 183, 146–159] based on the amino acid sequences of certain subgroups of aminotransferases as probes attributed significant Z scores in the range 5–20 SD to the deduced amino acid sequences of the above gene products as included in the protein data base. Reciprocal profile analyses confirmed the homologies. All known aminotransferases are pyridoxal‐5′‐phosphate‐dependent enzymes and catalyze the reversible transfer of amino groups from amino acids to oxo acids. The sequence homologies suggest that the above gene products are aminotransferases or other closely related pyridoxal‐5′‐phosphate‐dependent enzymes probably catalyzing transformations of amino acids involving cleavage of a bond at Cα.

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supporting

confidence: 74%

Homology of pyridoxal‐5′‐phosphate‐dependent aminotransferases with the cobC (cobalamin synthesis), nifS (nitrogen fixation), pabC (p‐aminobenzoate synthesis) and malY (abolishing endogenous induction of the maltose system) gene products

Mehta

Christen

1993

European Journal of Biochemistry

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“…Exposure to air or treatment of maltose 6P hydrolase with sulfhydryl-reactive agents leads to rapid loss of enzyme activity. These findings, together with the activation of the enzyme upon incubation of an extract in an anaerobic environment containing H 2 ( , and 28 Ni 2ϩ serve a structural or catalytic role has not been ascertained. It is notable that the four metals occur sequentially in the transition series of elements and usually exhibit a coordination number of 6.…”

Section: Discussionmentioning

confidence: 99%

“…Reports of maltose-PEP:PTS activity have engendered debate (5,12,20,28,41,49), and while phospho-␣-glucosidase (maltose phosphate hydrolase) activity in Streptococcus mutans has been suggested (49), the putative enzyme has never been isolated. Recent studies of carbohydrate metabolism by pathogenic fusobacteria (33,34,45) resulted, fortuitously, in the first preparative isolation of maltose 6P from any bacterial species (32).…”

mentioning

confidence: 99%

Purification from Fusobacterium mortiferum ATCC 25557 of a 6-phosphoryl-O-alpha-D-glucopyranosyl:6-phosphoglucohydrolase that hydrolyzes maltose 6-phosphate and related phospho-alpha-D-glucosides

et al. 1995

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6-Phosphoryl-O-␣-D-glucopyranosyl:6-phosphoglucohydrolase (6-phospho-␣-glucosidase) has been purified from Fusobacterium mortiferum ATCC 25557. p-Nitrophenyl-␣-D-glucopyranoside 6-phosphate (pNP␣Glc6P) served as the chromogenic substrate for detection and assay of enzyme activity. The O 2 -sensitive, metaldependent phospho-␣-glucosidase was stabilized during purification by inclusion of dithiothreitol and Mn 2؉ ion in chromatography buffers. Various 6-phosphoryl-O-␣-linked glucosides, including maltose 6-phosphate, pNP␣Glc6P, trehalose 6-phosphate, and sucrose 6-phosphate, were hydrolyzed by the enzyme to yield D-glucose 6-phosphate and aglycone moieties in a 1:1 molar ratio. 6-Phospho-␣-glucosidase (M r of ϳ49,000; pI of ϳ4.9) is activated by Fe 2؉, Mn 2؉, Co 2؉, and Ni 2؉, and the maximum rate of pNP␣Glc6P hydrolysis occurs at 40؇C within the pH range 7.0 to 7.5. The sequence of the first 32 amino acids of 6-phospho-␣-glucosidase exhibits 67% identity (90% similarity) to that deduced for the N terminus of a putative phospho-␤-glucosidase (designated ORF f212) encoded by glvG in Escherichia coli. Western blots involving highly specific polyclonal antibody against 6-phospho-␣-glucosidase and spectrophotometric analyses with pNP␣Glc6P revealed only low levels of the enzyme in glucose-, mannose-, or fructose-grown cells of F. mortiferum. Synthesis of 6-phospho-␣-glucosidase increased dramatically during growth of the organism on ␣-glucosides, such as maltose, ␣-methylglucoside, trehalose, turanose, and palatinose.A landmark in our understanding of carbohydrate dissimilation by microorganisms was established in 1964 by the serendipitous discovery of the phosphoenolpyruvate-dependent: sugar phosphotransferase system (PEP:PTS) by Saul Roseman and his colleagues (17, 35). Although first described for Escherichia coli, this group translocation system is now recognized as the primary mechanism for sugar accumulation by many species from both gram-negative (21, 26) and gram-positive bacterial genera (15,30,42,44). In a series of sequential transfers of the high-energy phosphoryl moiety from PEP, this multicomponent system catalyzes the simultaneous translocation and phosphorylation of sugars into the cell (21,26,36).The phosphorylated products of hexose-and polyol-specific PEP:PTSs may directly enter the energy-generating (fermentation) pathways of the organism. By contrast, further metabolism of intracellular disaccharide phosphates necessitates the initial cleavage of these compounds to yield the appropriate free and phosphorylated hexose moieties. Sugar-specific (and frequently inducible) hydrolases catalyze the cleavage of the O-glycosidic linkage of the various disaccharide phosphates. Several such enzymes have been described, including those responsible for the hydrolysis of 6-phospho-␤-galactosides (6, 14, 16), 6-phospho-␤-glucosides (38, 39, 48), sucrose 6-phosphate (sucrose 6P) (7,18,46), cellobiose 6P (22), and trehalose 6P (31).Reports of maltose-PEP:PTS activity have engendered debate (5, 12, 20, 28, 41, 49),...

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“…In addition, MalT is negatively controlled by at least three proteins: MalY, MalK, and Aes. MalY is an enzyme with cystathionine ␤-lyase activity (9,10), which interacts directly with the amino terminus of MalT (11,12), seemingly through a patch made up of a hydrophobic core surrounded by highly polar residues (13). MalK, the ATP-hydrolyzing subunit of the maltose transport system (14), has been reported to interact directly with MalT (15), probably through some residues localized in its C-terminal domain (16).…”

mentioning

confidence: 99%

The Aes Protein and the Monomeric α-Galactosidase fromEscherichia coli Form a Non-covalent Complex

Mandrich¹,

Caputo²,

Martin³

et al. 2002

Journal of Biological Chemistry

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Aes, a 36-kDa acetylesterase from Escherichia coli, belongs to the hormone-sensitive lipase family, and it is involved in the regulation of MalT, the transcriptional activator of the maltose regulon. The activity of MalT is depressed through a direct protein-protein interaction with Aes. Although the effect is clear-cut, the meaning of this interaction and the conditions that trigger it still remain elusive. To perform a comparative thermodynamic study between the mesophilic Aes protein and two homologous thermostable enzymes, Aes was overexpressed in E. coli and purified. At the last step of the purification procedure the enzyme was eluted from a Mono Q HR 5/5 column as a major form migrating, anomalously, at 56 kDa on a calibrated Superdex 75 column. A minor peak that contains the Aes protein and a polypeptide of 50 kDa was also detected. By a combined analysis of size-exclusion chromatography and surface-enhanced laser desorption ionization-time of flight mass spectrometry, it was possible to demonstrate the presence in this peak of a stable 87-kDa complex, containing the Aes protein itself and the 50-kDa polypeptide in a 1:1 ratio. The homodimeric molecular species of Aes and of the 50-kDa polypeptide were also detected. The esterase activity associated with the 87-kDa complex, when assayed with p-nitrophenyl butanoate as substrate, proved 6-fold higher than the activity of the major Aes form of 56 kDa. Amino-terminal sequencing highlighted that the 50-kDa partner of Aes in the complex was the ␣-galactosidase from E. coli. The E. coli cells harboring plasmid pT7-SCII-aes and, therefore, expressing Aes were hampered in their growth on a minimal medium containing raffinose as a sole carbon source. Because ␣-galactosidase is involved in the metabolism of raffinose, the above findings suggest a potential role of Aes in the regulation of carbohydrate metabolism in E. coli.The Escherichia coli aes (or ybac) gene encodes the 36-kDa cytoplasmic protein Aes (1), a carboxylesterase belonging to the hormone-sensitive lipase family (HSL) 1 (2). Although the physiological role of this enzyme is still obscure, it has recently received greater attention due to the discovery that Aes is involved in the regulation of the maltose regulon in E. coli (reviewed in Ref. 3). The E. coli maltose system consists of 10 genes encoding proteins for the uptake and metabolism of maltodextrin and maltose (3). MalT is the transcriptional activator of the maltose regulon and the prototype of a new family of transcription factors (4, 5) and integrates several signals through its amino-terminal three domains (6). To activate mal genes transcription MalT acts together with the cyclic AMPcatabolite protein complex, the inducer maltotriose, and ATP (7). Several regulatory circuits modulate the activity of MalT, e.g. MalT expression is regulated by Mlc, a glucose-inducible repressor (8). In addition, MalT is negatively controlled by at least three proteins: MalY, MalK, and Aes. MalY is an enzyme with cystathionine ␤-lyase activity (9, 10), which ...

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The malX malY operon of Escherichia coli encodes a novel enzyme II of the phosphotransferase system recognizing glucose and maltose and an enzyme abolishing the endogenous induction of the maltose system

Cited by 96 publications

References 79 publications

Homology of pyridoxal‐5′‐phosphate‐dependent aminotransferases with the cobC (cobalamin synthesis), nifS (nitrogen fixation), pabC (p‐aminobenzoate synthesis) and malY (abolishing endogenous induction of the maltose system) gene products

Homology of pyridoxal‐5′‐phosphate‐dependent aminotransferases with the cobC (cobalamin synthesis), nifS (nitrogen fixation), pabC (p‐aminobenzoate synthesis) and malY (abolishing endogenous induction of the maltose system) gene products

Purification from Fusobacterium mortiferum ATCC 25557 of a 6-phosphoryl-O-alpha-D-glucopyranosyl:6-phosphoglucohydrolase that hydrolyzes maltose 6-phosphate and related phospho-alpha-D-glucosides

The Aes Protein and the Monomeric α-Galactosidase fromEscherichia coli Form a Non-covalent Complex

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