Evidence for the evolutionary relatedness of the proteins of the bacterial phosphoenolpyruvate:Sugar phosphotransferase system

The phosphoenolpyruvate:sugar phosphotransferase system (PTS) consists of two general energy-coupling proteins, enzyme I and HPr, as well as the sugar-specific permeases, commonly referred to as the enzyme II complex (15,19,24,26). The system catalyzes the concomitant transport and phosphorylation of its sugar substrates in a process termed group translocation (16,25). The PTS permeases found in a variety of bacteria may consist of one, two, three, or four distinct polypeptide chains and, in certain instances, some of these sugar-specific proteins are fused to protein domains which serve the general energy-coupling function(s) of enzyme I and/or HPr (8,31,34) (see Fig. 1 and 2 for schematic depictions). Evidence suggesting that the entire enzyme II complex is required for concomitant sugar transport and phosphorylation but that enzyme I and HPr merely function to phosphorylate this complex has been presented (4, 9). The enzyme II complex should therefore be considered the functional unit designated permease in this paper.Recent sequence comparison studies have shown that most of the PTS permeases are homologous, i.e., derived from a common ancestral protein (13,21,28,33). These group translocators, comprising the major group of the enzyme II complexes, generally have similar molecular weights of about 68,000, corresponding to about 635 total amino acyl residues (31). Most of them consist either of a single polypeptide chain, commonly termed enzyme II, or of two proteins, commonly called an enzyme II-III pair or an enzyme IIB-IIA pair (15,31). In a few cases, these permeases consist of three or four proteins (6,14,22 [5, 12a, 14]). These three permeases of the splinter group lack sufficient sequence similarity with the major group of PTS permeases to establish homology with them, but they are clearly homologous to each other.At the present time, well over 12 PTS permeases have been completely sequenced. While the permeases within the major group are homologous, sequence comparisons have revealed that during their evolution, the various hydrophilic and hydrophobic domains have become either fused to each other in different orders and combinations or spliced from each other to become distinct polypeptide chains (2, 13, 22, 31, 34). The various possibilities are illustrated in Fig. 1 and 2. In some cases, sequence similarities among permeases are insufficient to establish homology, either for all or for part of a particular permease complex. Regardless of whether a PTS permease consists of one, two, three, or four polypeptide chains, the entire complex must probably be present in association with the membrane to efficiently transport sugar (4,5,9). It therefore seems that the proteins which constitute a PTS permease function as an enzyme unit, the enzyme II complex, and that the number of polypeptide chains as well as the order of the domains within any one protein constituent of a PTS permease is largely immaterial to the function of that permease.At present there is no uniform nomenclature for the proteins and pr...

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“…2, each half the size of the usual C domain (36). However, in many respects this permease resembles the others (30,35).…”

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confidence: 73%

Proposed uniform nomenclature for the proteins and protein domains of the bacterial phosphoenolpyruvate: sugar phosphotransferase system

1992

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“…The genes encoding more than dozen of these permeases have been sequenced, and their deduced aminoacyl sequences have been analyzed in some detail (4,5,12,56). Sequence comparisons have established that at least several of the PTS permeases are evolutionarily related, but the evolutionary relationships of others have not yet been demonstrable (12,52,56).…”

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confidence: 99%

Nucleotide sequence of the fruA gene, encoding the fructose permease of the Rhodobacter capsulatus phosphotransferase system, and analyses of the deduced protein sequence

Saier

1990

J Bacteriol

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The nucleotide sequence of thefruA gene, the terminal gene in the fructose operon of Rhodobacter capsulatus, is reported. This gene codes for the fructose permease (molecular weight, 58,575; 578 aminoacyl residues), the fructose enzyme II (IIH") of the phosphoenolpyruvate-dependent phosphotransferase system. The deduced aminoacyl sequence of the encoded gene product was found to be 55% identical throughout most of its length with the fructose enzyme H of Escherichia coli, with some regions strongly conserved and others weakly conserved. Sequence comparisons revealed that the first 100 aminoacyl residues of both enzymes II were homologous to the second 100 residues, suggesting that an intragenic duplication of about 300 nucleotides had occurred during the evolution of HF, prior to divergence of the E. coli and R. capsulatus genes. The protein contains only two cysteyl residues, and only one of these residues is conserved between the two proteins. This residue is therefore presumed to provide the active-site thiol group which may serve as the phosphorylation site. 1Fru was found to exhibit regions of homology with sequenced enzymes II from other bacteria, including those specific for sucrose, i-glucosides, mannitol, glucose, N-acetylglucosamine, and lactose. The degree of evolutionary divergence differed for different parts of the proteins, with certain transmembrane segments exhibiting high degrees of conservation. The hydrophobic domain of IIFIU was also found to be similar to several uniport and antiport transporters of animals, including the human and mouse insulin-responsive glucose facilitators. These observations suggest that the mechanism of transmembrane transport may be similar for permeases catalyzing group translocation and facilitated diffusion. (10) cloned the fructose (fru) operon from Rhodobacter capsulatus in preparation for sequence analyses. We had maintained that a fructose PTS might have been the primordial PTS and that analysis of the unusual fructose-specific PTS from these photosynthetic bacteria might provide insight into the evolution of the PTS (47, 52).In this paper, we report the complete nucleotide sequence of the R. capsulatus fruA gene which encodes the fructose enzyme II of the PTS in this organism. We show that the gene encodes a 578-residue protein which exhibits striking sequence identity throughout most of its length with the corresponding E. coli protein. Sequence analyses revealed that the N-terminal 100 amino acids of the primordial protein had been duplicated during its evolution and that it therefore possessed a 100-residue repeat unit at its N terminus.

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“…The 1-phosphohistidine in phospho-HPr undergoes spontaneous phosphohydrolysis independently of the presence of enzyme I or an enzyme II (37). The active site of HPr includes E-85, the C-terminal ␣-carboxyl group.…”

Section: Discussionmentioning

confidence: 99%

“…As shown previously (37), HPr(his-P) spontaneously hydrolyzes, and appropriate utilization of the assay for this reaction can allow estimation of the efficiency of phosphoryl transfer from enzyme I(his-P) to HPr. By using this assay under standard conditions with enzyme I and phosphoenolpyruvate present in excess, the D69E mutant HPr was found to undergo spontaneous hydrolysis at half the rate of the wild-type protein (Fig.…”

Section: Mtlmentioning

confidence: 91%

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Identification of a site in the phosphocarrier protein, HPr, which influences its interactions with sugar permeases of the bacterial phosphotransferase system: kinetic analyses employing site-specific mutants

Koch

Sutrina

et al. 1996

J Bacteriol

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The permeases of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system (PTS), the sugar-specific enzymes II, are energized by sequential phosphoryl transfer from phosphoenolpyruvate to (i) enzyme I, (ii) the phosphocarrier protein HPr, (iii) the enzyme IIA domains of the permeases, and (iv) the enzyme IIBC domains of the permeases which transport and phosphorylate their sugar substrates. A number of site-specific mutants of HPr were examined by using kinetic approaches. Most of the mutations exerted minimal effects on the kinetic parameters characterizing reactions involving phosphoryl transfer from phospho-HPr to various sugars. However, when the well-conserved aspartyl 69 residue in HPr was changed to a glutamyl residue, the affinities for phospho-HPr of the enzymes II specific for mannitol, N-acetylglucosamine, and ␤-glucosides decreased markedly without changing the maximal reaction rates. The same mutation reduced the spontaneous rate of phosphohistidyl HPr hydrolysis but did not appear to alter the rate of phosphoryl transfer from phospho-enzyme I to HPr. The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) catalyzes the concomitant chemoreception, transport, and phosphorylation of its numerous sugar substrates (19,27,32). It also regulates a variety of physiological processes in both gram-negative and gram-positive bacteria (31, 34). These processes include (i) catabolite repression, (ii) carbohydrate transport, (iii) carbon and energy metabolism, (iv) carbon storage, and (v) the coordination of carbon and nitrogen metabolism (20, 36). The regulatory functions of the PTS depend on its ability to serve as a protein kinase system. It phosphorylates various PTS and non-PTS proteins, thereby controlling their interactions with other macromolecules that influence catalysis or transcription. As some of these interactions apparently involve recognition of tertiary structure rather than primary structure (30), they can be influenced by alterations in residues distant from the sites of interaction (11,12,25,26,48,49).The generalized scheme for the PTS phosphoryl transfer chain is as follows (35): sugar sugar IIC sugar PEP™3 I ϳ P™3 HPr ϳ P™3 IIA ϳ P™3 IIB ϳ P™™™™3 sugar-P Several of these PTS proteins can transfer their phosphoryl moieties to non-PTS proteins (34). Central in this scheme is the small, non-sugar-specific phosphoryl transfer protein, HPr. It interacts with enzyme I, a variety of sugar-specific IIA protein constituents of the enzyme II complexes, and with non-PTS phosphorylation targets, including transcriptional antiterminators, non-PTS transport proteins, and enzymes (28,29,31,34).HPr of Escherichia coli is an 85-residue, heat-stable, singledomain, phosphoryl carrier protein (19,27). The amino acyl sequences of this protein and its homologs in various bacteria have been determined. Its homologs include fructose-inducible HPr-like protein domains, termed FPr (7, 50), the nitrogenrelated, regulatory HPr-like protein, termed NPr, encoded within the rpoN operon of ...

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Evidence for the evolutionary relatedness of the proteins of the bacterial phosphoenolpyruvate:Sugar phosphotransferase system

Cited by 81 publications

References 41 publications

Proposed uniform nomenclature for the proteins and protein domains of the bacterial phosphoenolpyruvate: sugar phosphotransferase system

Proposed uniform nomenclature for the proteins and protein domains of the bacterial phosphoenolpyruvate: sugar phosphotransferase system

Nucleotide sequence of the fruA gene, encoding the fructose permease of the Rhodobacter capsulatus phosphotransferase system, and analyses of the deduced protein sequence

Identification of a site in the phosphocarrier protein, HPr, which influences its interactions with sugar permeases of the bacterial phosphotransferase system: kinetic analyses employing site-specific mutants

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