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Gunhild Layer - One of the best experts on this subject based on the ideXlab platform.

  • the crystal structure of siroheme decarboxylase in complex with iron Uroporphyrin III reveals two essential histidine residues
    Journal of Molecular Biology, 2014
    Co-Authors: Kristin Haufschildt, Stefan Schmelz, Theresa M Kriegler, Dirk W Heinz, Judith Streif, Alexander Neumann, Hiroyuki Arai, Gunhild Layer
    Abstract:

    Abstract The isobacteriochlorin heme d 1 serves as an essential cofactor in the cytochrome cd 1 nitrite reductase NirS that plays an important role for denitrification. During the biosynthesis of heme d 1 , the enzyme siroheme decarboxylase catalyzes the conversion of siroheme to 12,18-didecarboxysiroheme. This enzyme was discovered recently (Bali S, Lawrence AD, Lobo SA, Saraiva LM, Golding BT, Palmer DJ et al. Molecular hijacking of siroheme for the synthesis of heme and d 1 heme. Proc Natl Acad Sci USA 2011;108:18260–5) and is only scarcely characterized. Here, we present the crystal structure of the siroheme decarboxylase from Hydrogenobacter thermophilus representing the first three-dimensional structure for this type of enzyme. The overall structure strikingly resembles those of transcriptional regulators of the Lrp/AsnC family. Moreover, the structure of the enzyme in complex with a substrate analog reveals first insights into its active-site architecture. Through site-directed mutagenesis and subsequent biochemical characterization of the enzyme variants, two conserved histidine residues within the active site are identified to be involved in substrate binding and catalysis. Based on our results, we propose a potential catalytic mechanism for the enzymatic reaction catalyzed by the siroheme decarboxylase.

Kristin Haufschildt - One of the best experts on this subject based on the ideXlab platform.

  • the crystal structure of siroheme decarboxylase in complex with iron Uroporphyrin III reveals two essential histidine residues
    Journal of Molecular Biology, 2014
    Co-Authors: Kristin Haufschildt, Stefan Schmelz, Theresa M Kriegler, Dirk W Heinz, Judith Streif, Alexander Neumann, Hiroyuki Arai, Gunhild Layer
    Abstract:

    Abstract The isobacteriochlorin heme d 1 serves as an essential cofactor in the cytochrome cd 1 nitrite reductase NirS that plays an important role for denitrification. During the biosynthesis of heme d 1 , the enzyme siroheme decarboxylase catalyzes the conversion of siroheme to 12,18-didecarboxysiroheme. This enzyme was discovered recently (Bali S, Lawrence AD, Lobo SA, Saraiva LM, Golding BT, Palmer DJ et al. Molecular hijacking of siroheme for the synthesis of heme and d 1 heme. Proc Natl Acad Sci USA 2011;108:18260–5) and is only scarcely characterized. Here, we present the crystal structure of the siroheme decarboxylase from Hydrogenobacter thermophilus representing the first three-dimensional structure for this type of enzyme. The overall structure strikingly resembles those of transcriptional regulators of the Lrp/AsnC family. Moreover, the structure of the enzyme in complex with a substrate analog reveals first insights into its active-site architecture. Through site-directed mutagenesis and subsequent biochemical characterization of the enzyme variants, two conserved histidine residues within the active site are identified to be involved in substrate binding and catalysis. Based on our results, we propose a potential catalytic mechanism for the enzymatic reaction catalyzed by the siroheme decarboxylase.

Suzanne T. Williams - One of the best experts on this subject based on the ideXlab platform.

  • Colorful seashells: Identification of haem pathway genes associated with the synthesis of porphyrin shell color in marine snails
    Ecology and Evolution, 2017
    Co-Authors: Suzanne T. Williams, Anne E. Lockyer, Patricia Dyal, Tomoyuki Nakano, Celia K. C. Churchill, Daniel I. Speiser
    Abstract:

    Very little is known about the evolution of molluskan shell pigments, although Mollusca is a highly diverse, species rich, and ecologically important group of animals comprised of many brightly colored taxa. The marine snail genus Clanculus was chosen as an exceptional model for studying the evolution of shell color, first, because in Clanculus margaritarius and Clanculus pharaonius both shell and foot share similar colors and patterns; and second, because recent studies have identified the pigments, trochopuniceus (pink-red), and trochoxouthos (yellow-brown), both comprised of Uroporphyrin I and Uroporphyrin III, in both shell and colored foot tissue of these species. These unusual characteristics provide a rare opportunity to identify the genes involved in color production because, as the same pigments occur in the shell and colored foot tissue, the same color-related genes may be simultaneously expressed in both mantle (which produces the shell) and foot tissue. In this study, the transcriptomes of these two Clanculus species along with a third species, Calliostoma zizyphinum, were sequenced to identify genes associated with the synthesis of porphyrins. Calliostoma zizyphinum was selected as a negative control as trochopuniceus and trochoxouthos were not found to occur in this species. As expected, genes necessary for the production of Uroporphyrin I and III were found in all three species, but gene expression levels were consistent with synthesis of Uroporphyrins in mantle and colored foot tissue only in Clanculus. These results are relevant not only to understanding the evolution of shell pigmentation in Clanculus but also to understanding the evolution of color in other species with Uroporphyrin pigmentation, including (mainly marine) mollusks soft tissues and shells, annelid and platyhelminth worms, and some bird feathers.

  • Identification of shell colour pigments in marine snails Clanculus pharaonius and C. margaritarius (Trochoidea; gastropoda)
    PloS one, 2016
    Co-Authors: Suzanne T. Williams, T. Henkel, L. F. C. De Oliveira, Shosuke Ito, Kazumasa Wakamatsu, Tomasz Goral, Nicholas P. Edwards, Roy A. Wogelius, Lenize F. Maia, Stanislav Strekopytov
    Abstract:

    Colour and pattern are key traits with important roles in camouflage, warning and attraction. Ideally, in order to begin to understand the evolution and ecology of colour in nature, it is important to identify and, where possible, fully characterise pigments using biochemical methods. The phylum Mollusca includes some of the most beautiful exemplars of biological pigmentation, with the vivid colours of sea shells particularly prized by collectors and scientists alike. Biochemical studies of molluscan shell colour were fairly common in the last century, but few of these studies have been confirmed using modern methods and very few shell pigments have been fully characterised. Here, we use modern chemical and multi-modal spectroscopic techniques to identify two porphyrin pigments and eumelanin in the shell of marine snails Clanculus pharaonius and C margaritarius. The same porphyrins were also identified in coloured foot tissue of both species. We use high performance liquid chromatography (HPLC) to show definitively that these porphyrins are Uroporphyrin I and Uroporphyrin III. Evidence from confocal microscopy analyses shows that the distribution of porphyrin pigments corresponds to the striking pink-red of C. pharaonius shells, as well as pink-red dots and lines on the early whorls of C. margaritarius and yellow-brown colour of later whorls. Additional HPLC results suggest that eumelanin is likely responsible for black spots. We refer to the two differently coloured porphyrin pigments as trochopuniceus (pink-red) and trochoxouthos (yellow-brown) in order to distinguish between them. Trochopuniceus and trochoxouthos were not found in the shell of a third species of the same superfamily, Calliostoma zizyphinum, despite its superficially similar colouration, suggesting that this species has different shell pigments. These findings have important implications for the study of colour and pattern in molluscs specifically, but in other taxa more generally, since this study shows that homology of visible colour cannot be assumed without identification of pigments.

Ali Abbas Falih Shindi - One of the best experts on this subject based on the ideXlab platform.

Stefan Schmelz - One of the best experts on this subject based on the ideXlab platform.

  • the crystal structure of siroheme decarboxylase in complex with iron Uroporphyrin III reveals two essential histidine residues
    Journal of Molecular Biology, 2014
    Co-Authors: Kristin Haufschildt, Stefan Schmelz, Theresa M Kriegler, Dirk W Heinz, Judith Streif, Alexander Neumann, Hiroyuki Arai, Gunhild Layer
    Abstract:

    Abstract The isobacteriochlorin heme d 1 serves as an essential cofactor in the cytochrome cd 1 nitrite reductase NirS that plays an important role for denitrification. During the biosynthesis of heme d 1 , the enzyme siroheme decarboxylase catalyzes the conversion of siroheme to 12,18-didecarboxysiroheme. This enzyme was discovered recently (Bali S, Lawrence AD, Lobo SA, Saraiva LM, Golding BT, Palmer DJ et al. Molecular hijacking of siroheme for the synthesis of heme and d 1 heme. Proc Natl Acad Sci USA 2011;108:18260–5) and is only scarcely characterized. Here, we present the crystal structure of the siroheme decarboxylase from Hydrogenobacter thermophilus representing the first three-dimensional structure for this type of enzyme. The overall structure strikingly resembles those of transcriptional regulators of the Lrp/AsnC family. Moreover, the structure of the enzyme in complex with a substrate analog reveals first insights into its active-site architecture. Through site-directed mutagenesis and subsequent biochemical characterization of the enzyme variants, two conserved histidine residues within the active site are identified to be involved in substrate binding and catalysis. Based on our results, we propose a potential catalytic mechanism for the enzymatic reaction catalyzed by the siroheme decarboxylase.