Role of extracellular GAPDH in Streptococcus pyogenes virulence.

Pathogens generate molecules, or virulence factors, that enable them to colonize host tissues through several mechanisms, including adhesion to host tissues, or superior invasive capability. Some allow the pathogen to evade the host's immune system. Many of these molecules are proteins that are exported to the cell's surface or secreted.

GAPDH in anesthesia.

Thus far, two independent laboratories have shown that inhaled anesthetics directly affect GAPDH structure and function. Additionally, it has been demonstrated that GAPDH normally regulates the function of GABA (type A) receptor. In light of these literature observations and some less direct findings, there is a discussion on the putative role of GAPDH in anesthesia.

Multiple binding partners.

GAPDH interacts with a plethora of diverse cellular proteins. The network of interacting partners, or interactome, is presented for GAPDH with the interacting molecules grouped into specific functional and structural categories. By organizing the binding partners in this way, certain common structural features are beginning to surface, such as acidic dipeptide sequences that are found in several of these binding proteins.

Dynamic oligomeric properties.

This chapter provides a foundation for further research into the relationship between dynamic oligomeric properties and functional diversity. The structural basis that underlies the conformational sub-states of the GAPDH oligomer is discussed. The issue of protein stability is given a thorough analysis, since it is well-established that the primary strategy for protein oligomerization is to stabilize conformation.

Target for diverse chemical modifications.

The chapter begins with an historical perspective of GAPDH isozymes that is juxtaposed to the fact that there is only one somatic functional gene in humans that is virtually identical among the mammalian species. Over the many years of GAPDH research, dozens of labs have reported the existence of multiple forms of GAPDH, which mostly vary as a function of charge with an occasional report of truncated forms. These observations are in part due to GAPDH being a substrate for many enzymatically-controlled post-translational modifications.

GAPDH, as a virulence factor.

Pathogens, such as bacteria, viruses, protozoa and fungi, generate molecules that provide them with a selective advantage, often at the expense of the host. These molecules, or virulence factors, enable pathogens to colonize the host through several mechanisms. Some molecules offer the pathogen an advantage through better adhesion to host tissues, or superior invasive capability.

Functional diversity.

There is increasing evidence to support a gene economy model that is fully based on the principles of evolution in which a limited number of proteins does not necessarily reflect a finite number of biochemical processes. The concept of 'gene sharing' proposes that a single protein can have alternate functions that are typically attributed to other proteins. GAPDH appears to play this role quite well in that it exhibits more than one function.

Compartmentation of GAPDH.

The concept of the cytosol as a space that contains discrete zones of metabolites is discussed relative to the contribution of GAPDH. GAPDH is directed to very specific cell compartments. This chapter describes the utilization of GAPDH's enzymatic function for focal demands (i.

GAPDH and intermediary metabolism.

GAPDH plays a major enzymatic role in the intermediary metabolism of human tissues. In fact, the cells of all organisms require the catalytic capability of GAPDH in order to maintain adequate glycolytic flux. Even the primitive archaea rely on GAPDH in a pivotal step in the Entner-Doudoroff pathway, which is a series of reactions that resembles glycolysis.

Basic biology of GAPDH.

The GAPDH gene is highly conserved with a promoter that contains several types of regulatory elements, perhaps even in a distal intron. Curiously, the transcription start site shows some ambiguity and there are codon-sharing exons at alternate exon junctions. While there is only one functional gene for GAPDH in humans, the genome is littered with pseudogenes, representing a trove of researchable content.

Protection against protein aggregation by alpha-crystallin as a mechanism of preconditioning.

Anesthetic preconditioning occurs when cells previously exposed to inhaled anesthetics are protected against subsequent injury. We hypothesize that inhaled anesthetics may cause slight protein misfolding that involves site-specific dehydration, stimulating cytoprotective mechanisms. Human neuroblastoma cells were exposed to ethanol (as the dehydration agent) followed by quantitative analysis of the expression of five heat shock genes: DNAJC5G, CRYAA, HSPB2, HSF4 and HSF2.

Isoflurane's Effect on Protein Conformation as a Proposed Mechanism for Preconditioning.

Persistent alteration of protein conformation due to interaction with isoflurane may be a novel molecular aspect of preconditioning. We preincubated human serum albumin with isoflurane, dialyzed to release agent, and assessed protein conformation. Susceptibility to chemical modification by methylglyoxal and nitrophenylacetate was also examined.

Isoflurane preconditioning involves upregulation of molecular chaperone genes.

Isoflurane preconditioning is a phenomenon in which cells previously exposed to isoflurane exhibit protection against subsequent noxious stimuli. We hypothesize that isoflurane may cause subtle protein misfolding that persists at a sublethal level, stimulating cytoprotective mechanisms. Human neuroblastoma cells (SH-SY5Y) were exposed to isoflurane followed by quantitative analysis of the expression of several families of heat shock genes (84 total transcripts).

Inhaled Anesthetics Promote Albumin Dimerization through Reciprocal Exchange of Subdomains.

Inhaled anesthetics affect protein-protein interaction, but the mechanisms underlying these effects are still poorly understood. We examined the impact of sevoflurane and isoflurane on the dimerization of human serum albumin (HSA), a protein with anesthetic binding sites that are well characterized. Intrinsic fluorescence emission was analyzed for spectral shifting and self-quenching, and control first derivatives (spectral responses to changes in HSA concentration) were compared against those obtained from samples treated with sevoflurane or isoflurane.

Carnosine protects against the neurotoxic effects of a serotonin-derived melanoid.

Anesthesia-related postoperative cognitive dysfunction (POCD) leads to morbidity in the elderly. Lipid peroxidative byproducts (i.e.

Isoflurane's effect on interfacial dynamics in GAPDH influences methylglyoxal reactivity.

Diabetic surgical patients are at risk for peri- and post-operative complications, which can be prevented by maintaining tight glycemic control during anesthesia. Control of blood sugar would decrease unwanted chemical reactions, such as protein glycation, minimizing tissue dysfunction. Methylglyoxal (MG) is a major contributor to protein modification and tissue dysfunction seen in diabetic patients.

Redox mechanism of neurotoxicity by a serotonin-acrolein polymeric melanoid.

Postoperative cognitive dysfunction may be associated with the toxic products of lipid peroxidation, such as the α,β-unsaturated aldehyde acrolein, which accumulates in aging. We previously identified an acrolein-mediated, serotonin-derived melanoid product, or SDM. This study further characterizes this putative novel neuromelanin, which is not made from catecholamines.

Toxicity of a serotonin-derived neuromelanin.

Postoperative Cognitive Dysfunction (POCD) is associated with increased mortality in the elderly and may occur from lipid peroxidation in aging. We previously showed that sevoflurane sequesters acrolein, which promotes the formation of a novel species of a putative neuromelanin. The current study examined the properties of this serotonin-derived melanoid (SDM).

Interfacial effects on the conformation of amyloid-beta peptide.

We examined the effects of air-water and water-sevoflurane interfaces on conformational properties of amyloid-beta peptide (ABP). Fractions were extracted from sub-interfacial (air-water) and supra-interfacial (water-sevoflurane) layers and compared with aqueous bulk layers using fluorescence properties of ABP provided by a single tyrosine. The observations suggest that interfacial ABP may be more disordered than bulk ABP.

Trifluoroethanol increases albumin's susceptibility to chemical modification.

Acrolein-dependent chemical modification is implicated in the etiology of postoperative cognitive dysfunction (POCD). We examined this process further using human serum albumin (HSA), which is a target of acrolein modification and contains anesthetic binding sites. We tested whether trifluoroethanol (TFE), which mimics inhaled anesthetics, affects the susceptibility of HSA to modification by acrolein.

Production of a novel neuromelanin at the sevoflurane-water interface.

Postoperative cognitive dysfunction (POCD) occurs in the elderly following surgery that requires inhaled anesthetics. The molecular mechanism associated with this process is unknown. This study examined the possible role of serotonin, a neurotransmitter involved in cognition.

Sevoflurane modulates the activity of glyceraldehyde 3-phosphate dehydrogenase.

The mechanism of inhalation anesthesia remains to be fully elucidated. While certain neuronal membrane proteins are considered sites of action, cytosolic proteins may also be targets. We hypothesize that inhaled anesthetics may act via glyceraldehyde 3-phosphate dehydrogenase (GAPDH), which has recently been shown to participate in neuronal inhibition.

Abeta-polyacrolein aggregates: novel mechanism of plastic formation in senile plaques.

High levels of acrolein (H2C=HC-CH=O) occur in Alzheimer's brain. Amyloid-beta (Abeta) peptide co-localizes with acrolein presumably due to Abeta-induced lipid peroxidation. Focal production of acrolein may yield a transient elevation in the concentration of acrolein that may be susceptible to polymerization via basic latex polymer chemistry.

Beta-alanine suppresses heat inactivation of lactate dehydrogenase.

Beta-Alanine exhibits neurotransmitter activity and is a component of the anti-glycation agent carnosine. We propose that beta-alanine may have additional properties which may be of physiological significance. Interestingly, stress modulates the level of beta-alanine, which regulates excitotoxicity responses and prevents neuronal cell death.

Anti-crosslinking properties of carnosine: significance of histidine.

Carnosine, a histidine-containing dipeptide, is a potential treatment for Alzheimer's disease. There is evidence that carnosine prevents oxidation and glycation, both of which contribute to the crosslinking of proteins; and protein crosslinking promotes beta-amyloid plaque formation. It was previously shown that carnosine has anti-crosslinking activity, but it is not known which of the chemical constituents are responsible.