Genetically Encoding Unnatural Amino Acids in Neurons In Vitro and in the Embryonic Mouse Brain for Optical Control of Neuronal Proteins.

Deciphering neuronal networks governing specific brain functions is a longstanding mission in neuroscience, yet global manipulation of protein functions pharmacologically or genetically lacks sufficient specificity to reveal a neuronal protein's function in a particular neuron or a circuitry. Photostimulation presents a great venue for researchers to control neuronal proteins with high temporal and spatial resolution. Recently, an approach to optically control the function of a neuronal protein directly in neurons has been demonstrated using genetically encoded light-sensitive Unnatural amino acids (Uaas). Here, we describe procedures for genetically incorporating Uaas into target neuronal proteins in neurons in vitro and in embryonic mouse brain. As an example, a photocaged Uaa was incorporated into an inwardly rectifying potassium channel Kir2.1 to render Kir2.1 photo-activatable. This method has the potential to be generally applied to many neuronal proteins to achieve optical regulation of different processes in brains. Uaas with other properties can be similarly incorporated into neuronal proteins in neurons for various applications.

Deficits in the activity of presynaptic γ-aminobutyric acid type B receptors contribute to altered neuronal excitability in fragile X syndrome.

The behavioral and anatomical deficits seen in fragile X syndrome (FXS) are widely believed to result from imbalances in the relative strengths of excitatory and inhibitory neurotransmission. Although modified neuronal excitability is thought to be of significance, the contribution that alterations in GABAergic inhibition play in the pathophysiology of FXS are ill defined. Slow sustained neuronal inhibition is mediated by γ-aminobutyric acid type B (GABAB) receptors, which are heterodimeric G-protein-coupled receptors constructed from R1a and R2 or R1b and R2 subunits. Via the activation of Gi/o, they limit cAMP accumulation, diminish neurotransmitter release, and induce neuronal hyperpolarization. Here we reveal that selective deficits in R1a subunit expression are seen in Fmr1 knock-out mice (KO) mice, a widely used animal model of FXS, but the levels of the respective mRNAs were unaffected. Similar trends of R1a expression were seen in a subset of FXS patients. GABAB receptors (GABABRs) exert powerful pre- and postsynaptic inhibitory effects on neurotransmission. R1a-containing GABABRs are believed to mediate presynaptic inhibition in principal neurons. In accordance with this result, deficits in the ability of GABABRs to suppress glutamate release were seen in Fmr1-KO mice. In contrast, the ability of GABABRs to suppress GABA release and induce postsynaptic hyperpolarization was unaffected. Significantly, this deficit contributes to the pathophysiology of FXS as the GABABR agonist (R)-baclofen rescued the imbalances between excitatory and inhibitory neurotransmission evident in Fmr1-KO mice. Collectively, our results provided evidence that selective deficits in the activity of presynaptic GABABRs contribute to the pathophysiology of FXS.

Optical Control of a Neuronal Protein Using a Genetically Encoded Unnatural Amino Acid in Neurons.

Photostimulation is a noninvasive way to control biological events with excellent spatial and temporal resolution. New methods are desired to photo-regulate endogenous proteins expressed in their native environment. Here, we present an approach to optically control the function of a neuronal protein directly in neurons using a genetically encoded unnatural amino acid (Uaa). By using an orthogonal tRNA/aminoacyl-tRNA synthetase pair to suppress the amber codon, a photo-reactive Uaa 4,5-dimethoxy-2-nitrobenzyl-cysteine (Cmn) is site-specifically incorporated in the pore of a neuronal protein Kir2.1, an inwardly rectifying potassium channel. The bulky Cmn physically blocks the channel pore, rendering Kir2.1 non-conducting. Light illumination instantaneously converts Cmn into a smaller natural amino acid Cys, activating Kir2.1 channel function. We express these photo-inducible inwardly rectifying potassium (PIRK) channels in rat hippocampal primary neurons, and demonstrate that light-activation of PIRK ceases the neuronal firing due to the outflux of K(+) current through the activated Kir2.1 channels. Using in utero electroporation, we also express PIRK in the embryonic mouse neocortex in vivo, showing the light-activation of PIRK in neocortical neurons. Genetically encoding Uaa imposes no restrictions on target protein type or cellular location, and a family of photoreactive Uaas is available for modulating different natural amino acid residues. This technique thus has the potential to be generally applied to many neuronal proteins to achieve optical regulation of different processes in brains. The current protocol presents an accessible procedure for intricate Uaa incorporation in neurons in vitro and in vivo to achieve photo control of neuronal protein activity on the molecular level.

In vivo expression of a light-activatable potassium channel using unnatural amino acids.

Optical control of protein function provides excellent spatial-temporal resolution for studying proteins in situ. Although light-sensitive exogenous proteins and ligands have been used to manipulate neuronal activity, a method for optical control of neuronal proteins using unnatural amino acids (Uaa) in vivo is lacking. Here, we describe the genetic incorporation of a photoreactive Uaa into the pore of an inwardly rectifying potassium channel Kir2.1. The Uaa occluded the pore, rendering the channel nonconducting, and, on brief light illumination, was released to permit outward K(+) current. Expression of this photoinducible inwardly rectifying potassium (PIRK) channel in rat hippocampal neurons created a light-activatable PIRK switch for suppressing neuronal firing. We also expanded the genetic code of mammals to express PIRK channels in embryonic mouse neocortex in vivo and demonstrated a light-activated PIRK current in cortical neurons. These principles could be generally expanded to other proteins expressed in the brain to enable optical regulation.

Crystal structure of phosphopantetheine adenylyltransferase from Enterococcus faecalis in the ligand-unbound state and in complex with ATP and pantetheine.

Phosphopantetheine adenylyltransferase (PPAT) catalyzes the reversible transfer of an adenylyl group from ATP to 4'-phosphopantetheine (Ppant) to form dephospho-CoA (dPCoA) and pyrophosphate in the Coenzyme A (CoA) biosynthetic pathway. Importantly, PPATs are the potential target for developing antibiotics because bacterial and mammalian PPATs share little sequence homology. Previous structural studies revealed the mechanism of the recognizing substrates and products. The binding modes of ATP, ADP, Ppant, and dPCoA are highly similar in all known structures, whereas the binding modes of CoA or 3'-phosphoadenosine 5'-phosphosulfate binding are novel. To provide further structural information on ligand binding by PPATs, the crystal structure of PPAT from Enterococcus faecalis was solved in three forms: (i) apo form, (ii) binary complex with ATP, and (iii) binary complex with pantetheine. The substrate analog, pantetheine, binds to the active site in a similar manner to Ppant. The new structural information reported in this study including pantetheine as a potent inhibitor of PPAT will supplement the existing structural data and should be useful for structure-based antibacterial discovery against PPATs.

Sasa quelpaertensis phenylpropanoid derivative suppresses lipopolysaccharide-induced nitric oxide synthase and cyclo-oxygenase-2 expressions in RAW 264.7 cells.

3-O-p-Coumaroyl-1-(4-hydroxy-3,5-dimethoxyphenyl)-1-O-ß-D-gulcopyranosylpropanol (ESQ10) is a naturally occurring phenylpropanoid derivative isolated from Sasa quelpaertensis (Gramineae). In the present study, we discovered that ESQ10 inhibits nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. ESQ10 attenuated LPS-induced synthesis of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in parallel and inhibited LPS-induced interleukin-6 production, as determined by an enzyme-linked immunosorbent assay in the macrophages. The mechanism of the antiinflammatory action of ESQ10, i.e., suppression of nuclear factor (NF)-κB and mitogen-activated protein kinase activation, has been documented. However, ESQ10 could not influence LPS-mediated IκB-α degradation and extracellular signal-regulated kinase/c-Jun amino-terminal kinase phosphorylation at concentrations of up to 373 µM. To test the potential application of ESQ10 as a topical material, we also conducted a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on human HaCaT keratinocytes as well as human dermal fibroblast cells. In this assay, ESQ10 did not induce cytotoxicity. Taken together, the results suggest that ESQ10 may be considered an antiinflammatory candidate for treating inflammatory and skin diseases.

Neolitsea sericea essential oil attenuates LPS-induced inflammation in RAW 264.7 macrophages by suppressing NF-kappaB and MAPK activation.

The chemical composition and anti-inflammatory activities of hydrodistilled essential oil from Neolitsea sericea leaves (NSE) have been investigated for the first time. The chemical constituents of NSE were analysed by GC-MS and found to include sericenine (32.3%), sabinene (21.0%), trans-beta-ocimene (13.3%), beta-caryophyllene (4.8%), and 4-terpineol (4.2%). The effects of NSE on nitric oxide (NO), prostaglandin E2 (PGE2), tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages were also examined. Pro-inflammatory cytokine and mediator tests indicated that NSE has excellent dose-dependent inhibitory activities. To further examine the mechanism responsible for the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression by NSE, we examined the effect of NSE on nuclear factor-kappaB (NF-kappaB) activation and the phosphorylation of mitogen-activated protein kinases (MAPK). NSE inhibited NF-kappaB activation by LPS, and this was associated with the abrogation of IkappaB-alpha phosphorylation and subsequent decreases in nuclear p50 and p65 protein levels. Further, the phosphorylation of p38, ERK and JNK was suppressed by NSE in a concentration-dependent manner. These results suggest that NSE exerts anti-inflammatory effects in LPS-stimulated RAW 264.7 macrophages by inhibition of NF-kappaB activation and MAPK phosphorylation, and, therefore, may be useful for treatment of inflammatory diseases.

The structure of Staphylococcus aureus phosphopantetheine adenylyltransferase in complex with 3'-phosphoadenosine 5'-phosphosulfate reveals a new ligand-binding mode.

Bacterial phosphopantetheine adenylyltransferase (PPAT) catalyzes the penultimate step in the coenzyme A (CoA) biosynthetic pathway. It catalyzes the reversible transfer of an adenylyl group from ATP to 4'-phosphopantetheine (Ppant) to form dephospho-CoA (dPCoA) and pyrophosphate. Previous structural studies have revealed how several ligands are recognized by bacterial PPATs. ATP, ADP, Ppant and dPCoA bind to the same binding site in a highly similar manner, while CoA binds to a partially overlapping site in a different mode. To provide further structural insights into ligand binding, the crystal structure of Staphylococcus aureus PPAT was solved in a binary complex with 3'-phosphoadenosine 5'-phosphosulfate (PAPS). This study unexpectedly revealed a new mode of ligand binding to PPAT, thus providing potentially useful information for structure-based discovery of inhibitors of bacterial PPATs.

Expression, crystallization and preliminary X-ray crystallographic analyses of two N-terminal acetyltransferase-related proteins from Thermoplasma acidophilum.

N-terminal acetylation is one of the most common protein modifications in eukaryotes, occurring in approximately 80-90% of cytosolic mammalian proteins and about 50% of yeast proteins. ARD1 (arrest-defective protein 1), together with NAT1 (N-acetyltransferase protein 1) and possibly NAT5, is responsible for the NatA activity in Saccharomyces cerevisiae. In mammals, ARD1 is involved in cell proliferation, neuronal development and cancer. Interestingly, it has been reported that mouse ARD1 (mARD1(225)) mediates epsilon-acetylation of hypoxia-inducible factor 1alpha (HIF-1alpha) and thereby enhances HIF-1alpha ubiquitination and degradation. Here, the preliminary X-ray crystallographic analyses of two N-terminal acetyltransferase-related proteins encoded by the Ta0058 and Ta1140 genes of Thermoplasma acidophilum are reported. The Ta0058 protein is related to an N-terminal acetyltransferase complex ARD1 subunit, while Ta1140 is a putative N-terminal acetyltransferase-related protein. Ta0058 shows 26% amino-acid sequence identity to both mARD1(225) and human ARD1(235). The sequence identity between Ta0058 and Ta1140 is 28%. Ta0058 and Ta1140 were overexpressed in Escherichia coli fused with an N-terminal purification tag. Ta0058 was crystallized at 297 K using a reservoir solution consisting of 0.1 M sodium acetate pH 4.6, 8%(w/v) polyethylene glycol 4000 and 35%(v/v) glycerol. X-ray diffraction data were collected to 2.17 A. The Ta0058 crystals belong to space group P4(1) (or P4(3)), with unit-cell parameters a = b = 49.334, c = 70.384 A, alpha = beta = gamma = 90 degrees. The asymmetric unit contains a monomer, giving a calculated crystal volume per protein weight (V(M)) of 2.13 A(3) Da(-1) and a solvent content of 42.1%. Ta1140 was also crystallized at 297 K using a reservoir solution consisting of 0.1 M trisodium citrate pH 5.6, 20%(v/v) 2-propanol, 20%(w/v) polyethylene glycol 4000 and 0.2 M sodium chloride. X-ray diffraction data were collected to 2.40 A. The Ta1140 crystals belong to space group R3, with hexagonal unit-cell parameters a = b = 75.174, c = 179.607 A, alpha = beta = 90, gamma = 120 degrees. Two monomers are likely to be present in the asymmetric unit, with a V(M) of 2.51 A(3) Da(-1) and a solvent content of 51.0%.

Overexpression, crystallization and preliminary X-ray crystallographic analysis of phosphopantetheine adenylyltransferase from Enterococcus faecalis.

Phosphopantetheine adenylyltransferase, an essential enzyme in the coenzyme A biosynthetic pathway, catalyzes the reversible transfer of an adenylyl group from ATP to 4'-phosphopantetheine, yielding 3'-dephospho-CoA and pyrophosphate. Enterococcus faecalis PPAT has been overexpressed in Escherichia coli as a fusion with a C-terminal purification tag and crystallized at 297 K using a reservoir solution consisting of 0.1 M sodium HEPES pH 7.5, 0.8 M sodium dihydrogen phosphate and 0.8 M potassium dihydrogen phosphate. X-ray diffraction data were collected to 2.70 A at 100 K. The crystals belong to the primitive tetragonal space group P4(1) (or P4(3)), with unit-cell parameters a = b = 160.81, c = 225.68 A. Four copies of the hexameric molecule are likely to be present in the asymmetric unit, giving a crystal volume per protein weight (V(M)) of 3.08 A(3) Da(-1) and a solvent content of 60.1%.

Overexpression, crystallization and preliminary X-ray crystallographic analysis of a putative transposase from Thermoplasma acidophilum encoded by the Ta0474 gene.

IS200 transposases, originally identified in Salmonella typhimurium LT2, are present in many bacteria and archaea and are distinct from other groups of transposases. To facilitate further structural comparisons among IS200-like transposases, structural analysis has been initiated of a putative transposase from Thermoplasma acidophilum encoded by the Ta0474 gene. Its 137-residue polypeptide shows high levels of sequence similarity to other members of the IS200 transposase family. The protein was overexpressed in intact form in Escherichia coli and crystallized at 297 K using a reservoir solution consisting of 100 mM Na HEPES pH 7.5 and 20%(v/v) ethanol. X-ray diffraction data were collected to 1.78 A. The crystals belong to the monoclinic space group P2(1), with unit-cell parameters a = 65.00, b = 34.07, c = 121.58 A, alpha = 90, beta = 100.20, gamma = 90 degrees. Four monomers, representing two copies of a dimeric molecule, are present in the asymmetric unit, giving a crystal volume per protein weight (V(M)) of 2.02 A(3) Da(-1) and a solvent content of 39.2%.

Crystal structure of a metal ion-bound IS200 transposase.

IS200 transposases, present in many bacteria and Archaea, appear to be distinct from other groups of transposases. To provide a structural basis for understanding the action of IS200 transposases, we have determined the crystal structure of the SSO1474 protein from Sulfolobus solfataricus, a member of the IS200 family, in both Mn(2+)-bound and Mn(2+)-free forms. Its monomer fold is distinct from other classes of structurally characterized transposases. Two monomers form a tight dimer by exchanging the C-terminal alpha-helix and by merging the two central beta-sheets into a large beta-sheet. Glu(55), His(62), and four water molecules provide the direct coordination sphere of the catalytically essential metal ion in the Mn(2+)-bound structure. His(16), Asp(59), and His(60) also play important roles in maintaining the metal binding site. The catalytic site is formed at the interface between monomers. The candidate nucleophile in the transposition mechanism, strictly conserved Tyr(121) coming from the other monomer, is turned away from the active site, suggesting that a conformational change is likely to occur during the catalytic cycle.

Relationship of urodynamic parameters and obesity in women with stress urinary incontinence.

OBJECTIVE: To identify the relationship of obesity and stress urinary incontinence and of obesity and urodynamic parameters in patients with stress urinary incontinence (SUI). STUDY DESIGN: The study included 98 women who were clinically diagnosed as having stress urinary incontinence and 102 women, the control group, who had no stress urinary incontinence. We compared body mass index (BMI) as a parameter of obesity between the two groups. BMI was defined as weight (in kilograms) divided by height (in square meters). All patients with SUI underwent urodynamic tests, and we determined the relationship between BMI and urodynamic parameters by using the Pearson correlation coefficient. RESULTS: There was no difference in age between the two groups. However, BMI was significantly higher in women with SUI than in the control group. There were more vaginal deliveries and higher parity in women with SUI than in the control group. BMI was significantly higher in women with SUI than in the control group only in the younger group, while parity and number of vaginal deliveries were higher in the SUI group than control group among all age groups. The coefficient of multiple logistic regression between obesity and SUI was .131 (r = .131). There was no relationship between BMI and urodynamic parameters among patients with SUI. The average intraabdominal pressure was significantly increased in the obese group over that in the nonobese group. Correlation between BMI and intraabdominal pressure showed a close relationship. CONCLUSION: BMI was higher in the SUI group than control group. Obesity may be an important etiologic factor in SUI but did not influence urodynamic parameters, and there was no relationship between BMI and urodynamic parameters.