Sulfhydrogenase/hydrogenase II (a.k.a. Sulfide dehydrogenase) [flavoprotein]; S° or polysulfide → sulfide.

MNPYRSYDARIIEVKELTSREKLFSLKFLDNEIEENFTFKPGQFVIVDIRGFGEFPISLC SSPTRRPIQLCIRRVGRMTKFIHKMNEGDIIGIRGPYGNGFPMDLMEGSNLILIAGGLGM APLRSVLWYAIDSGKYEKIYLFYGTKSYEDILFRDEIIHLLKHGEKLNCHVKLAYEVETP SCIYLERGFSEKVCKGVVTDLFRGEEFDVENSYALICGPPVMYKYVIRELLDRGLSPGRI YMTLERRMRCGVGKCGHCIVGTSVSIKYICKDGPVFTYWDALSTRGLI292

	PMID	Title & Author	Abstract	Year
0	10714990	Characterization of hydrogenase II from the hyperthermophilic archaeon Pyrococcus furiosus and assessment of its role in sulfur reduction. Ma K, Weiss R, Adams MW.	The fermentative hyperthermophile Pyrococcus furiosus contains an NADPH-utilizing, heterotetrameric (alphabetagammadelta), cytoplasmic hydrogenase (hydrogenase I) that catalyzes both H(2) production and the reduction of elemental sulfur to H(2)S. Herein is described the purification of a second enzyme of this type, hydrogenase II, from the same organism. Hydrogenase II has an M(r) of 320,000 +/- 20,000 and contains four different subunits with M(r)s of 52,000 (alpha), 39,000 (beta), 30,000 (gamma), and 24,000 (delta). The heterotetramer contained Ni (0.9 +/- 0.1 atom/mol), Fe (21 +/- 1.6 atoms/mol), and flavin adenine dinucleotide (FAD) (0.83 +/- 0.1 mol/mol). NADPH and NADH were equally efficient as electron donors for H(2) production with K(m) values near 70 microM and k(cat)/K(m) values near 350 min(-1) mM(-1). In contrast to hydrogenase I, hydrogenase II catalyzed the H(2)-dependent reduction of NAD (K(m), 128 microM; k(cat)/K(m), 770 min(-1) mM(-1)). Ferredoxin from P. furiosus was not an efficient electron carrier for either enzyme. Both H(2) and NADPH served as electron donors for the reduction of elemental sulfur (S(0)) and polysulfide by hydrogenase I and hydrogenase II, and both enzymes preferentially reduce polysulfide to sulfide rather than protons to H(2) using NADPH as the electron donor. At least two [4Fe-4S] and one [2Fe-2S] cluster were detected in hydrogenase II by electron paramagnetic resonance spectroscopy, but amino acid sequence analyses indicated a total of five [4Fe-4S] clusters (two in the beta subunit and three in the delta subunit) and one [2Fe-2S] cluster (in the gamma subunit), as well as two putative nucleotide-binding sites in the gamma subunit which are thought to bind FAD and NAD(P)(H). The amino acid sequences of the four subunits of hydrogenase II showed between 55 and 63% similarity to those of hydrogenase I. The two enzymes are present in the cytoplasm at approximately the same concentration. Hydrogenase II may become physiologically relevant at low S(0) concentrations since it has a higher affinity than hydrogenase I for both S(0) and polysulfide.	2000
1	9756361	Identification of shyc, a novel gene expressed in the murine developing and adult nervous system. Köster F, Schinke B, Niemann S, Hermans-Borgmeyer I.	The embryonal carcinoma cell line P19 responds to treatment with retinoid acid by differentiation into neuronal cell types [2]. Using radioactively labeled cDNA derived from differentiating P19 cells we screened an adult mouse brain cDNA library and isolated a gene named shyc for selective hybridizing clone. The encoded protein did not reveal homology to any known protein. We used in situ hybridization on mouse embryonic and adult brain sections to study shyc expression. The developing and embryonic nervous system showed the most prominent hybridization signals. In the adult brain the olfactory pathway was marked by shyc expression.	1998
2	23834664	Substrate specificity of an elongation-specific peptidoglycan endopeptidase and its implications for cell wall architecture and growth of Vibrio cholerae. Dörr T, Cava F, Lam H, Davis BM, Waldor MK.	The bacterial cell wall consists of peptidoglycan (PG), a sturdy mesh of glycan strands cross-linked by short peptides. This rigid structure constrains cell shape and size, yet is sufficiently dynamic to accommodate insertion of newly synthesized PG, which was long hypothesized, and recently demonstrated, to require cleavage of the covalent peptide cross-links that couple previously inserted material. Here, we identify several genes in Vibrio cholerae that collectively are required for growth - particularly elongation - of this pathogen. V. cholerae encodes three putative periplasmic proteins, here denoted ShyA, ShyB, and ShyC, that contain both PG binding and M23 family peptidase domains. While none is essential individually, the absence of both ShyA and ShyC results in synthetic lethality, while the absence of ShyA and ShyB causes a significant growth deficiency. ShyA is a D,d-endopeptidase able to cleave most peptide chain cross-links in V. cholerae's PG. PG from a ∆shyA mutant has decreased average chain length, suggesting that ShyA may promote removal of short PG strands. Unexpectedly, ShyA has little activity against muropeptides containing pentapeptides, which typically characterize newly synthesized material. ShyA's substrate-dependent activity may contribute to selection of cleavage sites in PG, whose implications for the process of side-wall growth are discussed.	2013

Ma, K., Weiss, R., and Adams, M.W. (2000) Characterization of hydrogenase II from the hyperthermophilic archaeon Pyrococcus furiosus and assessment of its role in sulfur reduction. J Bacteriol 182: 1864–1871.