Yeong‐Jae Seok

The histidine phosphocarrier protein (HPr) is an essential element in sugar transport by the bacterial phosphoenolpyruvate:sugar phosphotransferase system. Ligand fishing, using surface plasmon resonance, was used to show the binding of HPr to a nonphosphotransferase protein in extracts of Escherichia coli; the protein was subsequently identified as glycogen phosphorylase (GP). The high affinity (association constant approximately 10(8) M-1), species-specific interaction was also demonstrated in

The bacterial phosphoenolpyruvate:sugar phosphotransferase system regulates a variety of physiological processes as well as effecting sugar transport. The crr gene product (enzyme IIA(Glc) (IIA(Glc))) mediates some of these regulatory phenomena. In this report, we characterize a novel IIA(Glc)-binding protein from Escherichia coli extracts, discovered using ligand-fishing with surface plasmon resonance spectroscopy. This protein, which we named FrsA (fermentation/respiration switch protein), is

Bacteria respond to nutritional stresses by changing the cellular concentration of the alarmone (p)ppGpp. This control mechanism, called the stringent response, depends on two enzymes, the (p)ppGpp synthetase RelA and the bifunctional (p)ppGpp synthetase/hydrolase SpoT in <i>Escherichia coli</i> and related bacteria. Because SpoT is the only enzyme responsible for (p)ppGpp hydrolysis in these bacteria, SpoT activity needs to be tightly regulated to prevent the uncontrolled accumulation of (p)ppG

In addition to the phosphoenolpyruvate:sugar phosphotransferase system (sugar PTS), most proteobacteria possess a paralogous system (nitrogen phosphotransferase system, PTS(Ntr)). The first proteins in both pathways are enzymes (enzyme I(sugar) and enzyme I(Ntr)) that can be autophosphorylated by phosphoenolpyruvate. The most striking difference between enzyme I(sugar) and enzyme I(Ntr) is the presence of a GAF domain at the N-terminus of enzyme I(Ntr). Since the PTS(Ntr) was identified in 1995,

Because the phosphoenolpyruvate:sugar phosphotransferase system plays multiple regulatory roles in addition to the phosphorylation-coupled transport of many sugars in bacteria, synthesis of its protein components is regulated in a highly sophisticated way. Thus far, the cAMP receptor protein (CRP) complex and Mlc are known to be the major regulators of ptsHIcrr and ptsG expression in response to the availability of carbon sources. In this report, we performed ligand fishing experiments by using

While the proteins of the phosphoenolpyruvate:carbohydrate phosphotransferase system (carbohydrate PTS) have been shown to regulate numerous targets, little such information is available for the nitrogen-metabolic phosphotransferase system (nitrogen-metabolic PTS). To elucidate the physiological role of the nitrogen-metabolic PTS, we carried out phenotype microarray (PM) analysis with Escherichia coli K-12 strain MG1655 deleted for the ptsP gene encoding the first enzyme of the nitrogen-metaboli

Phosphorylation is the most important modification for protein regulation; it controls many signal transduction pathways in all organisms. While several tools to detect phosphorylated proteins have been developed to study a variety of basic cellular processes involving protein phosphorylation, these methods have several limitations. Many proteins exhibit a phosphorylation-dependent electrophoretic mobility shift (PDEMS) in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and

An Escherichia coli mutant devoid of enzyme IIA(Ntr) (EIIA(Ntr) ) of the nitrogen PTS is extremely sensitive to leucine-containing peptides due to decreased expression of acetohydroxy acid synthase. This decreased expression is due to defective potassium homeostasis. We further elucidate here the mechanism for regulation of gene expression by the intracellular level of K(+) . The leucine hypersensitivity of a ptsN (encoding EIIA(Ntr) ) mutant was suppressed by deleting rpoS, encoding the station

The first protein component of the Escherichia coli phosphoenolpyruvate: sugar phosphotransferase system (PTS) is the 64-kDa protein enzyme I (EI), which can be phosphorylated by phosphoenolpyruvate (PEP) and carry out phosphotransfer to the acceptor heat-stable protein (HPr). The isolated amino-terminal domain (EIN) of E. coli EI is no longer phosphorylated by PEP but retains the ability to participate in reversible phosphotransfer to HPr. An expression vector was constructed for the production

Bacteria sense continuous changes in their environment and adapt metabolically to effectively compete with other organisms for limiting nutrients. One system which plays an important part in this adaptation response is the phosphoenol-pyruvate:sugar phosphotransferase system (PTS). Many proteins interact with and are regulated by PTS components in bacteria. Here we review the interaction with and allosteric regulation of Escherichia coli glycogen phosphorylase (GP) activity by the histidine phos

To survive in a continuously changing environment, bacteria sense concentration gradients of attractants or repellents, and purposefully migrate until a more favourable habitat is encountered. While glucose is known as the most effective attractant, the flagellar biosynthesis and hence chemotactic motility has been known to be repressed by glucose in some bacteria. To date, the only known regulatory mechanism of the repression of flagellar synthesis by glucose is via downregulation of the cAMP l

Faecalibacterium prausnitzii (F. prausnitzii) is one of the most abundant bacteria in the human intestine, with its anti-inflammatory effects establishing it as a major effector in human intestinal health. However, its extreme sensitivity to oxygen makes its cultivation and physiological study difficult. F. prausnitzii produces butyric acid, which is beneficial to human gut health. Butyric acid is a short-chain fatty acid (SCFA) produced by the fermentation of carbohydrates, such as dietary fibr

Sugar transport by some permeases in Escherichia coli is allosterically regulated by the phosphorylation state of the intracellular regulatory protein, enzyme IIAglc of the phosphoenolpyruvate:sugar phosphotransferase system. A sensitive radiochemical assay for the interaction of enzyme IIAglc with membrane-associated lactose permease was used to characterize the binding reaction. The binding is stimulated by transportable substrates such as lactose, melibiose, and raffinose, but not by sugars t

The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) consists of two general energy-coupling proteins [enzyme I and histidine phosphocarrier protein (HPr)] and several sugar-specific enzyme IIs. Although, in addition to the phosphorylation-coupled transport of sugars, various regulatory roles of PTS components have been identified in Escherichia coli, much less is known about the PTS in the opportunistic human pathogen Vibrio vulnificus. In this study, we have identified pyruv

Faecalibacterium prausnitzii is a dominant member of healthy human colon microbiota, regarded as a beneficial gut bacterium due to its ability to produce anti-inflammatory substances. However, little is known about how F. prausnitzii utilizes the nutrients present in the human gut, influencing its prevalence in the host intestinal environment. The phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS) is a widely distributed and highly efficient carbohydrate transport system foun