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16 results on '"Siebel, Judith F."'

1. Direct Observation of an Iron-Bound Terminal Hydride in [FeFe]-Hydrogenase by Nuclear Resonance Vibrational Spectroscopy

Author

Reijerse, Edward J., primary, Pham, Cindy C., additional, Pelmenschikov, Vladimir, additional, Gilbert-Wilson, Ryan, additional, Adamska-Venkatesh, Agnieszka, additional, Siebel, Judith F., additional, Gee, Leland B., additional, Yoda, Yoshitaka, additional, Tamasaku, Kenji, additional, Lubitz, Wolfgang, additional, Rauchfuss, Thomas B., additional, and Cramer, Stephen P., additional

Published
2017
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2. Metal selectivity of the E. coli nickel metallochaperone, SlyD

Author

Kaluarachchi, Harini, Siebel, Judith F., Kaluarachchi-Duffy, Supipi, Krecisz, Sandra, Sutherland, Duncan E. K., Stillman, Martin J., and Zamble, Deborah B.

Subjects
Manganese, Circular Dichroism, Escherichia coli Proteins, Iron, Cobalt, Peptidylprolyl Isomerase, Article, Mass Spectrometry, Protein Structure, Tertiary, Zinc, Metals, Nickel, Escherichia coli, Copper
Abstract

SlyD is a Ni(II)-binding protein that contributes to nickel homeostasis in Escherichia coli. The C-terminal domain of SlyD contains a rich variety of metal-binding amino acids, suggesting broader metal binding capabilities, and previous work demonstrated that the protein can coordinate several types of first-row transition metals. However, the binding of SlyD to metals other than Ni(II) has not been previously characterized. To improve our understanding of the in vitro metal-binding activity of SlyD and how it correlates with the in vivo function of this protein, the interactions between SlyD and the series of biologically relevant transition metals [Mn(II), Fe(II), Co(II), Cu(I), and Zn(II)] were examined by using a combination of optical spectroscopy and mass spectrometry. Binding of SlyD to Mn(II) or Fe(II) ions was not detected, but the protein coordinates multiple ions of Co(II), Zn(II), and Cu(I) with appreciable affinity (K(D) values in or below the nanomolar range), highlighting the promiscuous nature of this protein. The order of affinities of SlyD for the metals examined is as follows: Mn(II) and Fe(II)Co(II)Ni(II) ~ Zn(II) ≪ Cu(I). Although the purified protein is unable to overcome the large thermodynamic preference for Cu(I) and exclude Zn(II) chelation in the presence of Ni(II), in vivo studies reveal a Ni(II)-specific function for the protein. Furthermore, these latter experiments support a specific role for SlyD as a [NiFe]-hydrogenase enzyme maturation factor. The implications of the divergence between the metal selectivity of SlyD in vitro and the specific activity in vivo are discussed.

Published
2011

12. Spectroscopic Investigations of [FeFe] Hydrogenase Maturated with [57Fe2(adt)(CN)2(CO)44]2-.

Author

Gilbert-Wilson, Ryan, Siebel, Judith F., Adamska-Venkatesh, Agnieszka, Pham, Cindy C., Reijerse, Edward, Hongxin Wang, Cramer, Stephen P., Lubitz, Wolfgang, and Rauchfuss, Thomas B.

Subjects
*SPECTRUM analysis, *HYDROGENASE, *CHEMICAL synthesis, *CRYSTALLOGRAPHY, *CHLAMYDOMONAS reinhardtii, *MOSSBAUER spectroscopy, *NUCLEAR resonance reactions
Abstract

The preparation and spectroscopic characterization of a CO-inhibited [FeFe] hydrogenase with a selectively 57Fe-labeled binuclear subsite is described. The precursor [57Fe2(adt)(CN)2(CO)4]2- was synthesized from the 57Fe metal, S8, CO, (NEt4)CN, NH4Cl, and CH2O. (Et4N )2[57Fe2(adt) (CN)2(CO)4] was then used for the maturation of the [FeFe] hydrogenase HydAl from Chlamydomonas reinhardtii, to yield the enzyme selectively labeled at the [2Fe]H subcluster. Complementary, 57Fe enrichment of the [4Fe-4S]H cluster was realized by reconstitution with 57FeCl3 and Na2S. The Hox-CO state of [257Fe]H and [457Fe-4S]H HydA1 was characterized by Mossbauer, HYSCORE, ENDOR, and nuclear resonance vibrational spectroscopy. [ABSTRACT FROM AUTHOR]

Published
2015
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15. Spectroscopic Characterization of the Bridging Amine in the Active Site of [FeFe] Hydrogenase Using Isotopologues of the H-Cluster

Author

Adamska-Venkatesh, Agnieszka, Roy, Souvik, Siebel, Judith F., Simmons, Trevor R., Fontecave, Marc, Artero, Vincent, Reijerse, Edward, Lubitz, Wolfgang, Adamska-Venkatesh, Agnieszka, Roy, Souvik, Siebel, Judith F., Simmons, Trevor R., Fontecave, Marc, Artero, Vincent, Reijerse, Edward, and Lubitz, Wolfgang

Abstract

The active site of [FeFe] hydrogenase contains a catalytic binuclear iron subsite coordinated by CN– and CO ligands as well as a unique azadithiolate (adt2–) bridging ligand. It has been established that this binuclear cofactor is synthesized and assembled by three maturation proteins HydE, -F, and -G. By means of in vitro maturation in the presence of 15N- and 13C-labeled tyrosine it has been shown that the CN– and CO ligands originate from tyrosine. The source of the bridging adt2– ligand, however, remains unknown. In order to identify the nitrogen of the bridging amine using HYSCORE spectroscopy and distinguish its spectroscopic signature from that of the CN– nitrogens, we studied three isotope-labeled variants of the H-cluster (15N-adt2–/C14N–, 15N-adt2–/C15N–, and 14N-adt2–/C15N–) and extracted accurate values of the hyperfine and quadrupole couplings of both CN– and adt2– nitrogens. This will allow an evaluation of isotopologues of the H-cluster generated by in vitro bioassembly in the presence of various 15N-labeled potential precursors as possible sources of the bridging ligand.

16. Insertion of heme b into the structure of the Cys34-carbamidomethylated human lipocalin α(1)-microglobulin: formation of a [(heme)(2) (α(1)-Microglobulin)](3) complex.

Author

Siebel JF, Kosinsky RL, Åkerström B, and Knipp M

Subjects
Alpha-Globulins metabolism, Chromatography, Gel methods, Heme metabolism, Humans, Lipocalins metabolism, Protein Folding, Spectrophotometry, Alpha-Globulins chemistry, Heme chemistry, Lipocalins chemistry
Abstract

α(1)-Microglobulin (α(1)m) is a 26 kDa plasma and tissue protein belonging to the lipocalin protein family. Previous investigations indicate that the protein interacts with heme and suggest that it has a function in heme metabolism. However, detailed characterizations of the α(1)m-heme interactions are lacking. Here, we report for the first time the preparation and analysis of a stable α(1)m-heme complex upon carbamidomethylation of the reactive Cys34 by using recombinantly expressed human α(1)m. Analytical size-exclusion chromatography coupled with a diode-array absorbance spectrophotometry demonstrates that at first an α(1)m-heme monomer is formed. Subsequently, a second heme triggers oligomerization that leads to trimerization. The resulting (α(1)m[heme](2))(3) complex was characterized by resonance Raman and EPR spectroscopy, which support the presence of two ferrihemes, thus indicating an unusual spin-state admixed ground state with S=(3)/(2), (5)/(2)., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Published
2012
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