Hui-Woog Choe - Academia.edu (original) (raw)

Papers by Hui-Woog Choe

ChemPhysChem, 2010

Recombinant phytochromes Agp1 and Agp2 from Agrobacterium tumefaciens are used as model phytochro... more Recombinant phytochromes Agp1 and Agp2 from Agrobacterium tumefaciens are used as model phytochromes for biochemical and biophysical studies. In biliverdin binding phytochromes the site for covalent attachment of the chromophore lies in the N‐terminal region of the protein, different from plant phytochromes. The issue which stereochemistry the chromophore adopts in the so‐called Pr and Pfr forms is addressed by using a series of locked chromophores which form spectrally characteristic adducts with Agp1 and Agp2. Studies on light‐induced conformational changes of Agp1 give an insight into how the intrinsic histidine kinase is modulated by light. Comparison of the crystal structure of an Agp1 fragment with other phytochrome crystal structures supports the idea that a light induced rearrangement of subunits within the homodimer modulates the activity of the kinase.

European Journal of Biochemistry

Two mutants of ribonuclease T1 (RNaseTl), [59-tyrosine]ribonuclease T1 (W59Y) and [45tryptophan,5... more Two mutants of ribonuclease T1 (RNaseTl), [59-tyrosine]ribonuclease T1 (W59Y) and [45tryptophan,59-tyrosine]ribonuclease T1 (Y45W/W59Y) possess between 150% and 190% wild-type activity. They have been crystallised as complexes of the inhibitor 2'-guanylic acid and analysed by X-ray diffraction at resolutions of 0.23 nm and 0.24 nm, respectively. The space group for both is monoclinic, P2,, with two molecules/asymmetric unit, W59Y: a = 4.934 nm, b = 4.820 nm, c = 4.025 nm, p = 90.29'. Y45WW59Y: a = 4.915 nm, b = 4.815 nm, c = 4.015 nm, p = 90.35'. Compared to wild-type RNaseTl in complex with 2'-guanylic acid (2'GMP) both mutant inhibitor complexes indicate that the replacement of Trp59 by Tyr leads to a 0.04-nm inward shift of the single a-helix and to significant differences in the active-site geometry, inhibitor conformation and inhibitor binding. Calorimetric studies of a range of mutants [24-tryptophan]ribonuclease T1 (Y24W), [42-tryptophan]ribonuclease T1 (Y42W), [45-tryptophan]ribonuclease T1 (Y45W), [92alanine]ribonuclease T1 (H92A) and [92-threonine]ribonuclease T1 (H92T) with and without the further mutation Trp59-Tyr showed that mutant proteins for which Trp59 is replaced by Tyr exhibit slightly decreased thermal stability.

Acta Crystallographica Section D-biological Crystallography, 2003

Acta crystallographica. Section D, Biological crystallography, 2003

Single crystals of alpha-cyclodextrin glucanotransferase isolated from Bacillus macerans have bee... more Single crystals of alpha-cyclodextrin glucanotransferase isolated from Bacillus macerans have been grown with polyethylene glycol 6000 as a precipitating agent by sitting-drop vapour diffusion at room temperature. The crystals were suitable for X-ray analysis and diffracted to at least 2.0 A (space group P2(1)2(1)2(1)), with unit-cell parameters a = 66.79 (2), b = 79.66 (1), c = 141.16 (1) A. Assuming the asymmetric cell to be occupied by a monomer of 74 kDa, the unit cell contains 42.6% solvent with a crystal Volume per protein mass, V(M), of 2.53 A(3) Da(-1).

Cyclodextrin glucanotransferase [CGTase, E.C.2.4.1.19] is an extracellular enzyme, which catalyze... more Cyclodextrin glucanotransferase [CGTase, E.C.2.4.1.19] is an extracellular enzyme, which catalyzes the formation of a-, j3-, ;-CDs from starch. Their proportions of formations depend on enzyme sources and reaction conditions. To understand what determines the product specificity of CGTases, we examined the alteration of product specificity of CGTase from Bacillus macerans by organic solvents and pH. At acidic pH range less than pH 6 where the enzyme was unstable, the ratio of a-//~-CD production was increased 4 times more than that at neutral pH range. As we increased the concentration of 2-butanol, a-//3-CD ratio was proportionally increased but/ratio remained constant. The a-/~-CD ratio of products was increased in the reaction media which yielded low products.

Molecular and cellular biology, 2002

Photoexcitation of rhodopsin activates a heterotrimeric G-protein cascade leading to cyclic GMP h... more Photoexcitation of rhodopsin activates a heterotrimeric G-protein cascade leading to cyclic GMP hydrolysis in vertebrate photoreceptors. Light-induced exchanges of the visual G-protein transducin between the outer and inner segment of rod photoreceptors occur through the narrow connecting cilium. Here we demonstrate that transducin colocalizes with the Ca(2+)-binding protein centrin 1 in a specific domain of this cilium. Coimmunoprecipitation, centrifugation, centrin overlay, size exclusion chromatography, and kinetic light-scattering experiments indicate that Ca(2+)-activated centrin 1 binds with high affinity and specificity to transducin. The assembly of centrin-G-protein complex is mediated by the betagamma-complex. The Ca(2+)-dependent assembly of a G protein with centrin is a novel aspect of the supply of signaling proteins in sensory cells and a potential link between molecular translocations and signal transduction in general.

Vision Research, 2006

Centrins are members of the family of Ca(2+)-binding EF-hand proteins. In photoreceptor cells, ce... more Centrins are members of the family of Ca(2+)-binding EF-hand proteins. In photoreceptor cells, centrin isoform 1 is specifically localized in the non-motile cilium. This connecting cilium links the light-sensitive outer segment with the biosynthetic active inner segment of the photoreceptor cell. All intracellular exchanges between these compartments have to occur through this cilium. Three-dimensional structures of centrins from diverse organisms are known, showing that the EF-hand motifs of the N-terminal domains adopt closed conformations, while the C-terminal EF-hand motifs have open conformations. The crystal structure of an N-terminally extended mouse centrin 1 (MmCen1-L) resembles the overall structure of troponin C in its two Ca(2+) bound form. Within the N-terminal extension in MmCen1-L, residues W24 and R25 bind to the C-terminal domain of centrin 1 in a target-protein-like geometry. Here, we discuss this binding mode in connection with putative interaction sites of the target-protein transducin and the self-assembly of centrins.

Nature, 1998

Retinal arrestin is the essential protein for the termination of the light response in vertebrate... more Retinal arrestin is the essential protein for the termination of the light response in vertebrate rod outer segments. It plays an important role in quenching the light-induced enzyme cascade by its ability to bind to phosphorylated light-activated rhodopsin (P-Rh*). Arrestins are found in various G-protein-coupled amplification cascades. Here we report on the three-dimensional structure of bovine arrestin (relative molecular mass, 45,300) at 3.3 A resolution. The crystal structure comprises two domains of antiparallel beta-sheets connected through a hinge region and one short alpha-helix on the back of the amino-terminal fold. The binding region for phosphorylated light-activated rhodopsin is located at the N-terminal domain, as indicated by the docking of the photoreceptor to the three-dimensional structure of arrestin. This agrees with the interpretation of binding studies on partially digested and mutated arrestin.

Trends in Biochemical Sciences, 2009

European Journal of Biochemistry, 1994

Two mutants of ribonuclease T1 (RNaseTl), [59-tyrosine]ribonuclease T1 (W59Y) and [45tryptophan,5... more Two mutants of ribonuclease T1 (RNaseTl), [59-tyrosine]ribonuclease T1 (W59Y) and [45tryptophan,59-tyrosine]ribonuclease T1 (Y45W/W59Y) possess between 150% and 190% wild-type activity. They have been crystallised as complexes of the inhibitor 2'-guanylic acid and analysed by X-ray diffraction at resolutions of 0.23 nm and 0.24 nm, respectively. The space group for both is monoclinic, P2,, with two molecules/asymmetric unit, W59Y: a = 4.934 nm, b = 4.820 nm, c = 4.025 nm, p = 90.29'. Y45WW59Y: a = 4.915 nm, b = 4.815 nm, c = 4.015 nm, p = 90.35'. Compared to wild-type RNaseTl in complex with 2'-guanylic acid (2'GMP) both mutant inhibitor complexes indicate that the replacement of Trp59 by Tyr leads to a 0.04-nm inward shift of the single a-helix and to significant differences in the active-site geometry, inhibitor conformation and inhibitor binding. Calorimetric studies of a range of mutants [24-tryptophan]ribonuclease T1 (Y24W), [42-tryptophan]ribonuclease T1 (Y42W), [45-tryptophan]ribonuclease T1 (Y45W), [92alanine]ribonuclease T1 (H92A) and [92-threonine]ribonuclease T1 (H92T) with and without the further mutation Trp59-Tyr showed that mutant proteins for which Trp59 is replaced by Tyr exhibit slightly decreased thermal stability.

European Journal of Biochemistry, 1993

The crystal structure of the complex between ribonuclease T1 and 3'GMP suggests that (a) a substr... more The crystal structure of the complex between ribonuclease T1 and 3'GMP suggests that (a) a substrate GpN is bound to the active site of ribonuclease T1 in a conformation that actively supports the catalytic process, (b) the reaction occurs in an in-line process, (c) His40 NEH' activates 02'-H, (d) Glu58 carboxylate acts as base and His92 NEH' as acid in a general acid-base catalysis.

European Journal of Biochemistry, 1993

The ternary complex formed between RNase T1, guanosine 3',5 and Pi crystallizes in the cubic spac... more The ternary complex formed between RNase T1, guanosine 3',5 and Pi crystallizes in the cubic space group I23 with a = 8.706(1) nm. In a previous publication [Lenz, A., Heinemann, U., Maslowska, M. & Saenger, W. (1991) Acta Crystallogr. B47,521-5271, the structure of the complex (in which Pi was not located) was described at a resolution of 0.32 nm. This is now extended to 0.19 nm with newly grown, larger crystals. Refinement with restrained least-squares converged at R = 17.8% for 8027 reflections with IFo[ 2 lc(lFol); the final model comprises 120 water molecules. 3',5'-pGp is bound to RNase T1 in the anti form, with guanine in the specific recognition site; the 3'-phosphate protrudes into the solvent, and the 5'-phosphate hydrogen bonds with Lys41 0 and Am43 N4. A tetrahedral anion assigned as Pi occupies the catalytic site and hydrogen bonds to the side chains of Tyr38, Glu58, Arg77 and His92. The overall polypeptide fold of RNase T1 in the cubic space group does not differ significantly from that in the orthorhombic space group P212121 except for changes < 0.2 nm in loop regions 69 -72 and 95 -98.

ChemPhysChem, 2010

Recombinant phytochromes Agp1 and Agp2 from Agrobacterium tumefaciens are used as model phytochro... more Recombinant phytochromes Agp1 and Agp2 from Agrobacterium tumefaciens are used as model phytochromes for biochemical and biophysical studies. In biliverdin binding phytochromes the site for covalent attachment of the chromophore lies in the N‐terminal region of the protein, different from plant phytochromes. The issue which stereochemistry the chromophore adopts in the so‐called Pr and Pfr forms is addressed by using a series of locked chromophores which form spectrally characteristic adducts with Agp1 and Agp2. Studies on light‐induced conformational changes of Agp1 give an insight into how the intrinsic histidine kinase is modulated by light. Comparison of the crystal structure of an Agp1 fragment with other phytochrome crystal structures supports the idea that a light induced rearrangement of subunits within the homodimer modulates the activity of the kinase.

European Journal of Biochemistry

Two mutants of ribonuclease T1 (RNaseTl), [59-tyrosine]ribonuclease T1 (W59Y) and [45tryptophan,5... more Two mutants of ribonuclease T1 (RNaseTl), [59-tyrosine]ribonuclease T1 (W59Y) and [45tryptophan,59-tyrosine]ribonuclease T1 (Y45W/W59Y) possess between 150% and 190% wild-type activity. They have been crystallised as complexes of the inhibitor 2'-guanylic acid and analysed by X-ray diffraction at resolutions of 0.23 nm and 0.24 nm, respectively. The space group for both is monoclinic, P2,, with two molecules/asymmetric unit, W59Y: a = 4.934 nm, b = 4.820 nm, c = 4.025 nm, p = 90.29'. Y45WW59Y: a = 4.915 nm, b = 4.815 nm, c = 4.015 nm, p = 90.35'. Compared to wild-type RNaseTl in complex with 2'-guanylic acid (2'GMP) both mutant inhibitor complexes indicate that the replacement of Trp59 by Tyr leads to a 0.04-nm inward shift of the single a-helix and to significant differences in the active-site geometry, inhibitor conformation and inhibitor binding. Calorimetric studies of a range of mutants [24-tryptophan]ribonuclease T1 (Y24W), [42-tryptophan]ribonuclease T1 (Y42W), [45-tryptophan]ribonuclease T1 (Y45W), [92alanine]ribonuclease T1 (H92A) and [92-threonine]ribonuclease T1 (H92T) with and without the further mutation Trp59-Tyr showed that mutant proteins for which Trp59 is replaced by Tyr exhibit slightly decreased thermal stability.

Acta Crystallographica Section D-biological Crystallography, 2003

Acta crystallographica. Section D, Biological crystallography, 2003

Single crystals of alpha-cyclodextrin glucanotransferase isolated from Bacillus macerans have bee... more Single crystals of alpha-cyclodextrin glucanotransferase isolated from Bacillus macerans have been grown with polyethylene glycol 6000 as a precipitating agent by sitting-drop vapour diffusion at room temperature. The crystals were suitable for X-ray analysis and diffracted to at least 2.0 A (space group P2(1)2(1)2(1)), with unit-cell parameters a = 66.79 (2), b = 79.66 (1), c = 141.16 (1) A. Assuming the asymmetric cell to be occupied by a monomer of 74 kDa, the unit cell contains 42.6% solvent with a crystal Volume per protein mass, V(M), of 2.53 A(3) Da(-1).

Cyclodextrin glucanotransferase [CGTase, E.C.2.4.1.19] is an extracellular enzyme, which catalyze... more Cyclodextrin glucanotransferase [CGTase, E.C.2.4.1.19] is an extracellular enzyme, which catalyzes the formation of a-, j3-, ;-CDs from starch. Their proportions of formations depend on enzyme sources and reaction conditions. To understand what determines the product specificity of CGTases, we examined the alteration of product specificity of CGTase from Bacillus macerans by organic solvents and pH. At acidic pH range less than pH 6 where the enzyme was unstable, the ratio of a-//~-CD production was increased 4 times more than that at neutral pH range. As we increased the concentration of 2-butanol, a-//3-CD ratio was proportionally increased but/ratio remained constant. The a-/~-CD ratio of products was increased in the reaction media which yielded low products.

Molecular and cellular biology, 2002

Photoexcitation of rhodopsin activates a heterotrimeric G-protein cascade leading to cyclic GMP h... more Photoexcitation of rhodopsin activates a heterotrimeric G-protein cascade leading to cyclic GMP hydrolysis in vertebrate photoreceptors. Light-induced exchanges of the visual G-protein transducin between the outer and inner segment of rod photoreceptors occur through the narrow connecting cilium. Here we demonstrate that transducin colocalizes with the Ca(2+)-binding protein centrin 1 in a specific domain of this cilium. Coimmunoprecipitation, centrifugation, centrin overlay, size exclusion chromatography, and kinetic light-scattering experiments indicate that Ca(2+)-activated centrin 1 binds with high affinity and specificity to transducin. The assembly of centrin-G-protein complex is mediated by the betagamma-complex. The Ca(2+)-dependent assembly of a G protein with centrin is a novel aspect of the supply of signaling proteins in sensory cells and a potential link between molecular translocations and signal transduction in general.

Vision Research, 2006

Centrins are members of the family of Ca(2+)-binding EF-hand proteins. In photoreceptor cells, ce... more Centrins are members of the family of Ca(2+)-binding EF-hand proteins. In photoreceptor cells, centrin isoform 1 is specifically localized in the non-motile cilium. This connecting cilium links the light-sensitive outer segment with the biosynthetic active inner segment of the photoreceptor cell. All intracellular exchanges between these compartments have to occur through this cilium. Three-dimensional structures of centrins from diverse organisms are known, showing that the EF-hand motifs of the N-terminal domains adopt closed conformations, while the C-terminal EF-hand motifs have open conformations. The crystal structure of an N-terminally extended mouse centrin 1 (MmCen1-L) resembles the overall structure of troponin C in its two Ca(2+) bound form. Within the N-terminal extension in MmCen1-L, residues W24 and R25 bind to the C-terminal domain of centrin 1 in a target-protein-like geometry. Here, we discuss this binding mode in connection with putative interaction sites of the target-protein transducin and the self-assembly of centrins.

Nature, 1998

Retinal arrestin is the essential protein for the termination of the light response in vertebrate... more Retinal arrestin is the essential protein for the termination of the light response in vertebrate rod outer segments. It plays an important role in quenching the light-induced enzyme cascade by its ability to bind to phosphorylated light-activated rhodopsin (P-Rh*). Arrestins are found in various G-protein-coupled amplification cascades. Here we report on the three-dimensional structure of bovine arrestin (relative molecular mass, 45,300) at 3.3 A resolution. The crystal structure comprises two domains of antiparallel beta-sheets connected through a hinge region and one short alpha-helix on the back of the amino-terminal fold. The binding region for phosphorylated light-activated rhodopsin is located at the N-terminal domain, as indicated by the docking of the photoreceptor to the three-dimensional structure of arrestin. This agrees with the interpretation of binding studies on partially digested and mutated arrestin.

Trends in Biochemical Sciences, 2009

European Journal of Biochemistry, 1994

Two mutants of ribonuclease T1 (RNaseTl), [59-tyrosine]ribonuclease T1 (W59Y) and [45tryptophan,5... more Two mutants of ribonuclease T1 (RNaseTl), [59-tyrosine]ribonuclease T1 (W59Y) and [45tryptophan,59-tyrosine]ribonuclease T1 (Y45W/W59Y) possess between 150% and 190% wild-type activity. They have been crystallised as complexes of the inhibitor 2'-guanylic acid and analysed by X-ray diffraction at resolutions of 0.23 nm and 0.24 nm, respectively. The space group for both is monoclinic, P2,, with two molecules/asymmetric unit, W59Y: a = 4.934 nm, b = 4.820 nm, c = 4.025 nm, p = 90.29'. Y45WW59Y: a = 4.915 nm, b = 4.815 nm, c = 4.015 nm, p = 90.35'. Compared to wild-type RNaseTl in complex with 2'-guanylic acid (2'GMP) both mutant inhibitor complexes indicate that the replacement of Trp59 by Tyr leads to a 0.04-nm inward shift of the single a-helix and to significant differences in the active-site geometry, inhibitor conformation and inhibitor binding. Calorimetric studies of a range of mutants [24-tryptophan]ribonuclease T1 (Y24W), [42-tryptophan]ribonuclease T1 (Y42W), [45-tryptophan]ribonuclease T1 (Y45W), [92alanine]ribonuclease T1 (H92A) and [92-threonine]ribonuclease T1 (H92T) with and without the further mutation Trp59-Tyr showed that mutant proteins for which Trp59 is replaced by Tyr exhibit slightly decreased thermal stability.

European Journal of Biochemistry, 1993

The crystal structure of the complex between ribonuclease T1 and 3'GMP suggests that (a) a substr... more The crystal structure of the complex between ribonuclease T1 and 3'GMP suggests that (a) a substrate GpN is bound to the active site of ribonuclease T1 in a conformation that actively supports the catalytic process, (b) the reaction occurs in an in-line process, (c) His40 NEH' activates 02'-H, (d) Glu58 carboxylate acts as base and His92 NEH' as acid in a general acid-base catalysis.

European Journal of Biochemistry, 1993

The ternary complex formed between RNase T1, guanosine 3',5 and Pi crystallizes in the cubic spac... more The ternary complex formed between RNase T1, guanosine 3',5 and Pi crystallizes in the cubic space group I23 with a = 8.706(1) nm. In a previous publication [Lenz, A., Heinemann, U., Maslowska, M. & Saenger, W. (1991) Acta Crystallogr. B47,521-5271, the structure of the complex (in which Pi was not located) was described at a resolution of 0.32 nm. This is now extended to 0.19 nm with newly grown, larger crystals. Refinement with restrained least-squares converged at R = 17.8% for 8027 reflections with IFo[ 2 lc(lFol); the final model comprises 120 water molecules. 3',5'-pGp is bound to RNase T1 in the anti form, with guanine in the specific recognition site; the 3'-phosphate protrudes into the solvent, and the 5'-phosphate hydrogen bonds with Lys41 0 and Am43 N4. A tetrahedral anion assigned as Pi occupies the catalytic site and hydrogen bonds to the side chains of Tyr38, Glu58, Arg77 and His92. The overall polypeptide fold of RNase T1 in the cubic space group does not differ significantly from that in the orthorhombic space group P212121 except for changes < 0.2 nm in loop regions 69 -72 and 95 -98.