Structural and Biochemical Identification of a Novel Bacterial Oxidoreductase

By using a bioinformatics screen of the Escherichia coli genome for potential molybdenum-containing enzymes, we have identified a novel oxidoreductase conserved in the majority of Gram-negative bacteria. The identified operon encodes for a proposed heterodimer, YedYZ in Escherichia coli, consisting of a soluble catalytic subunit termed YedY, which is likely anchored to the membrane by a heme-containing trans-membrane subunit termed YedZ. YedY is uniquely characterized by the presence of one molybdenum molybdopterin not conjugated by an additional nucleotide, and it represents the only molybdoenzyme isolated from E. coli characterized by the presence of this cofactor form. We have further characterized the catalytic subunit YedY in both the molybdenum- and tungsten-substituted forms by using crystallographic analysis. YedY is very distinct in overall architecture from all known bacterial reductases but does show some similarity with the catalytic domain of the eukaryotic chicken liver sulfite oxidase. However, the strictly conserved residues involved in the metal coordination sphere and in the substrate binding pocket of YedY are strikingly different from that of chicken liver sulfite oxidase, suggesting a catalytic activity more in keeping with a reductase than that of a sulfite oxidase. Preliminary kinetic analysis of YedY with a variety of substrates supports our proposal that YedY and its many orthologues may represent a new type of membrane-associated bacterial reductase. By using a bioinformatics screen of the Escherichia coli genome for potential molybdenum-containing enzymes, we have identified a novel oxidoreductase conserved in the majority of Gram-negative bacteria. The identified operon encodes for a proposed heterodimer, YedYZ in Escherichia coli, consisting of a soluble catalytic subunit termed YedY, which is likely anchored to the membrane by a heme-containing trans-membrane subunit termed YedZ. YedY is uniquely characterized by the presence of one molybdenum molybdopterin not conjugated by an additional nucleotide, and it represents the only molybdoenzyme isolated from E. coli characterized by the presence of this cofactor form. We have further characterized the catalytic subunit YedY in both the molybdenum- and tungsten-substituted forms by using crystallographic analysis. YedY is very distinct in overall architecture from all known bacterial reductases but does show some similarity with the catalytic domain of the eukaryotic chicken liver sulfite oxidase. However, the strictly conserved residues involved in the metal coordination sphere and in the substrate binding pocket of YedY are strikingly different from that of chicken liver sulfite oxidase, suggesting a catalytic activity more in keeping with a reductase than that of a sulfite oxidase. Preliminary kinetic analysis of YedY with a variety of substrates supports our proposal that YedY and its many orthologues may represent a new type of membrane-associated bacterial reductase. Molybdenum-coordinating enzymes fall within the broad class of enzymes associated with redox metabolic functions in prokaryotic and eukaryotic cells. The structurally characterized enzymes can be roughly grouped into three separate families (the bacterial/eukaryotic xanthine oxidase family, the eukaryotic sulfite oxidase family, and the bacterial Me2SO reductase family), each distinctive with respect to active site structure and the type of reaction they catalyze (1Hille R. Trends Biochem. Sci. 2002; 27: 360-367Abstract Full Text Full Text PDF PubMed Scopus (358) Google Scholar). The family of xanthine oxidases contains 1 eq of a pterin cofactor coordinated to the molybdenum metal with the typical pentavalent, approximately octahedral coordination sphere in the oxidized state completed not by any side chains from the enzyme but rather by a double-bonded sulfur atom, a double-bonded oxygen atom, and an oxygen atom with a single bond (2Enroth C. Eger B.T. Okamoto K. Nishino T. Pai E.F. Proc. Natl. Acad. Sci. U. S. A. 2000; 97: 10723-10728Crossref PubMed Scopus (593) Google Scholar). Sulfite oxidases have 1 eq of a pterin cofactor with the molybdenum coordinated by a cysteine ligand from the enzyme and two oxo groups (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar, 4Schrader N. Fischer K. Theis K. Mendel R.R. Schwarz G. Kisker C. Structure (Lond.). 2003; 11: 1251-1263Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar). Kappler et al. (5Kappler U. Bennett B. Rethmeier J. Schwarz G. Deutzmann R. McEwan A.G. Dahl C. J. Biol. Chem. 2000; 275: 13202-13212Abstract Full Text Full Text PDF PubMed Scopus (143) Google Scholar) described the spectroscopic and enzymologic characterization of a member of the sulfite oxidase family from Thiobacillus novellus, and they showed that the enzyme contains a molybdopterin-type cofactor, but no structural data are available for bacterial sulfite oxidase family members to verify the nature of the cofactor or overall architecture of this enzyme. The Me2SO reductase family is diverse in both structure and function, but all members have 2 eq of the pterin cofactor, and the molybdenum coordination sphere is usually completed by a single oxo group and a sixth ligand that can be a serine as in Me2SO reductase (6Schindelin H. Kisker C. Hilton J. Rajagopalan K.V. Rees D.C. Science. 1996; 272: 1615-1621Crossref PubMed Scopus (442) Google Scholar), a cysteine in nitrate reductase (7Dias J.M. Than M.E. Humm A. Huber R. Bourenkov G.P. Bartunik H.D. Bursakov S. Calvete J. Caldeira J. Carneiro C. Moura J.J. Moura I. Romao M.J. Struct. Fold Des. 1999; 7: 65-79Abstract Full Text Full Text PDF Scopus (287) Google Scholar), a selenocysteine in formate dehydrogenase H (8Boyington J.C. Gladyshev V.N. Khangulov S.V. Stadtman Science. 1997; 275: PubMed Scopus Google Scholar), and a in oxidase T. R. Structure (Lond.). Full Text Full Text PDF PubMed Scopus Google Scholar). et al. C. J.H. Struct. Biol. 2003; PubMed Scopus Google Scholar) the nitrate reductase structure with the molybdenum coordinated by an are conserved the family to which they and the more only the residues involved in the active site are this we the structure of YedY from Escherichia coli The for YedY identified in the E. coli genome G. J. J. B. Science. 1997; PubMed Scopus Google Scholar) as a novel and it to have a molybdopterin-type cofactor similarity with known structural and analysis that YedY the catalytic subunit of a novel membrane-associated in the majority of Gram-negative bacteria. YedY is the only molybdoenzyme isolated from E. coli with the molybdopterin-type cofactor, and it represents the structural characterization of this of cofactor in and of a member of the bacterial sulfite oxidase the overall of YedY is to domain of the eukaryotic chicken sulfite oxidase chicken liver sulfite sulfite molybdenum and sulfite oxidase our structural data that the active site of YedY which a catalytic activity more in keeping with a reductase rather than a sulfite oxidase enzyme. are by kinetic data with a variety of and of E. coli genome G. J. J. B. Science. 1997; PubMed Scopus Google Scholar) for potential novel similarity with known identified in this The contains YedY and as J. R. A. G. and J. H. in the The in E. coli with the The in J. Scholar) with the of metal J.H. J. PubMed Google Scholar), the with 1 The in of in a and with The for a further to in the cofactor, in in which the 1 with The in in and by to the presence of in the the isolated by the described R. R. J. PubMed Google Scholar, J. Biol. Chem. Full Text PDF PubMed Google Scholar). both the from the by with a type and soluble The to a with and with a of The further by a the molybdenum cofactor not to the it to a with that to with the in the E. coli as the as described Struct. Biol. 2002; Google Scholar), and the by the as for The to a of and in in to the presence of a and in the domain of E. they from soluble or from the we the in a and of as by and The for of of cells. The of residues in the by that the is and is as in The of molybdenum and by not of YedY as as for of a with an a using and using sulfite oxidase activity as described by using I. J. Biol. Chem. Full Text PDF PubMed Google Scholar) or Rajagopalan K.V. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar) as and the of sulfite and kinetic using a and a of and the YedY reductase activity as described J.H. 1996; PubMed Scopus Google Scholar). of the using a of of and a of The with the of and enzyme. data the of and kinetic data of and by by by using of and of of the group with a and in using of within and to by using the as YedY, using and in the form. and to have and the is which to a of in the with a and using a and consisting of in a to have and the is which to a of and Structure data K. into of the of 1 and for YedY and the and 1 for and the an a of data with 1997; PubMed Scopus Google Scholar) and with the an a of the of The data with and with S. Biol. PubMed Scopus Google and in to the in to the is the of a of and are and structure of from the to in to the is the of a and are and structure of from the to in a new by using and R. J. 1999; Scopus Google Scholar), and by E. G. 1997; PubMed Scopus Google Scholar). three of in the identified and as for J. Biol. 1999; PubMed Scopus Google Scholar) to the two and to to a of of for all data from to The using and with Biol. 2000; PubMed Scopus Google Scholar), which to the to the data and to the the of for all data from to using J. Struct. Biol. 1999; PubMed Scopus Google Scholar), consisting of residues of one which as a in S. Biol. PubMed Scopus Google Scholar) for the The data and in J. T. Biol. PubMed Scopus Google Scholar). The of the the and to in the of of and with The for tungsten-substituted YedY by with S. Biol. PubMed Scopus Google Scholar) using the of YedY as and it data in J. T. Biol. PubMed Scopus Google Scholar). the of for data and are in I. The molybdenum cofactor, and the oxo and groups all to the two additional of the molybdenum by using of both oxo and one two and of or we this one atom be identified as an oxo group of of and no but the atom, which with the be as a the ligand and to the or as an oxo the molybdenum with a bond to an which in to the data or a be to two for this The with and of residues in the and in the additional of the J.M. J. Google Scholar), for and and for and of each be in the of a The of the E. coli genome G. J. J. B. Science. 1997; PubMed Scopus Google Scholar), a of of function, for novel and this we the E. coli genome for potential novel identified in this the presence of a of YedY is a soluble with a for by the C. T. J. PubMed Scopus Google Scholar, J.H. Cell. Full Text Full Text PDF PubMed Scopus Google Scholar), with a of is proposed to be the catalytic subunit of the heterodimer, our analysis suggesting the presence of for one redox analysis and of J. T. G. Proc. Natl. Acad. Sci. U. S. A. 2002; PubMed Scopus Google Scholar), suggesting a potential in YedY to the bacterial analysis and the of the oxidized with PubMed Scopus Google Scholar) are of a with an not that is likely to and in the overall with analysis of the YedY and be to that is the redox for YedYZ orthologues are in a variety of of and and The members of this broad family of are in with and are in of structure and YedY and its orthologues with characterized the sulfite Me2SO and xanthine with no of the catalytic groups in have the structure of YedY using from YedY is a of structure with overall and an of The overall of YedY of into two and are and they are of the molybdenum cofactor The the two and of the which a and The are and to and are and the of the and they a the side of the YedY no structural with the bacterial molybdenum cofactor enzymes of the families Me2SO reductase (7Dias J.M. Than M.E. Humm A. Huber R. Bourenkov G.P. Bartunik H.D. Bursakov S. Calvete J. Caldeira J. Carneiro C. Moura J.J. Moura I. Romao M.J. Struct. Fold Des. 1999; 7: 65-79Abstract Full Text Full Text PDF Scopus (287) Google Scholar) or xanthine oxidase M.J. Moura I. Moura J.J. J. R. Huber R. Science. PubMed Scopus Google Scholar) and architecture of of the YedY The are The to the is The molybdenum are in and with the molybdenum in The with Science. PubMed Scopus Google Scholar). of the the presence of a the site of the and of conserved residues the The with The Scholar), and the with Science. PubMed Scopus Google of YedY with the available in the using the C. Trends Biochem. Sci. Full Text PDF PubMed Scopus Google that the of YedY is to that of with a of of the two (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar) the single YedY domain is to only domain of (the with a of for structure but to the two additional one of which is for and the of which is for the binding of not in a sulfite oxidase, that of the A. N. Fischer K. Theis K. Mendel R.R. Schwarz G. Kisker C. Structure (Lond.). 2003; 11: 1251-1263Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar) structural similarity with YedY of for YedY only with the domain from and no structural to the domain of the enzyme. are YedY in the of the enzyme by a The of residues all both the and the and the for the residues and are with a of of from the of The forms a structure with an of and each subunit only two of the of the The the are the and with the all are in a that the all the a conserved of each to the domain to an that a in membrane with its redox YedZ. However, the of the of YedY is The each of in the is with J. S. C. J. Biol. PubMed Scopus Google Scholar), but the the or that are only and no the in and are characterized by distinct that and of and the presence of (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar, 4Schrader N. Fischer K. Theis K. Mendel R.R. Schwarz G. Kisker C. Structure (Lond.). 2003; 11: 1251-1263Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar). YedY is as a in of using analysis not The of enzymes are into three distinctive structure and the type of reaction (1Hille R. Trends Biochem. Sci. 2002; 27: 360-367Abstract Full Text Full Text PDF PubMed Scopus (358) Google Scholar). the only xanthine oxidase and xanthine dehydrogenase from (2Enroth C. Eger B.T. Okamoto K. Nishino T. Pai E.F. Proc. Natl. Acad. Sci. U. S. A. 2000; 97: 10723-10728Crossref PubMed Scopus (593) Google Scholar) and sulfite oxidases from chicken liver (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar) and from A. N. Fischer K. Theis K. Mendel R.R. Schwarz G. Kisker C. Structure (Lond.). 2003; 11: 1251-1263Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar) are characterized by the presence of a single molybdopterin not conjugated by oxidase and dehydrogenase have an in the oxidized with 1 eq of the pterin cofactor coordinated to the metal and a double-bonded sulfur atom, a double-bonded oxygen atom, and an oxygen atom with a single bond the coordination sphere (2Enroth C. Eger B.T. Okamoto K. Nishino T. Pai E.F. Proc. Natl. Acad. Sci. U. S. A. 2000; 97: 10723-10728Crossref PubMed Scopus (593) Google Scholar). The oxidoreductase from the only structurally characterized of a bacterial enzyme from the xanthine oxidase family, a molybdenum cofactor to the enzyme from but is conjugated by a J.M. J.M. Huber R. Moura J.J. Romao M.J. J. Biol. Chem. PubMed Scopus Google Scholar). sulfite oxidases the metal a single of the pterin cofactor, but as of an with a cysteine ligand by the and two oxo groups the coordination of the metal (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar, 4Schrader N. Fischer K. Theis K. Mendel R.R. Schwarz G. Kisker C. Structure (Lond.). 2003; 11: 1251-1263Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar). The active site of YedY novel that have no in characterized bacterial The molybdenum cofactor of a single molybdopterin that is that the molybdenum atom is from the enzyme The cofactor is within the enzyme active the molybdenum is to in all structurally characterized molybdenum enzymes (2Enroth C. Eger B.T. Okamoto K. Nishino T. Pai E.F. Proc. Natl. Acad. Sci. U. S. A. 2000; 97: 10723-10728Crossref PubMed Scopus (593) Google Scholar, C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar, 4Schrader N. Fischer K. Theis K. Mendel R.R. Schwarz G. Kisker C. Structure (Lond.). 2003; 11: 1251-1263Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar, H. Kisker C. Hilton J. Rajagopalan K.V. Rees D.C. Science. 1996; 272: 1615-1621Crossref PubMed Scopus (442) Google Scholar, J.M. Than M.E. Humm A. Huber R. Bourenkov G.P. Bartunik H.D. Bursakov S. Calvete J. Caldeira J. Carneiro C. Moura J.J. Moura I. Romao M.J. Struct. Fold Des. 1999; 7: 65-79Abstract Full Text Full Text PDF Scopus (287) Google Scholar, M.J. Moura I. Moura J.J. J. R. Huber R. Science. PubMed Scopus Google Scholar, H. Huber R. Proc. Natl. Acad. Sci. U. S. A. 1999; PubMed Scopus Google Scholar, J.J. Theis K. S. R. Rajagopalan K.V. Kisker C. Structure (Lond.). 2002; Full Text Full Text PDF PubMed Scopus Google Scholar), the pterin is of a with the to the of the The molybdopterin is not conjugated by an additional nucleotide, and YedY represents the only structure of a prokaryotic enzyme with a molybdopterin-type The molybdenum cofactor forms with and side in YedY, which are strictly conserved the family of bacterial 1 and The pterin with the by and the group is by additional by and that the molybdenum cofactor to the enzyme are distinct from in the eukaryotic oxidase enzymes that a (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar, 4Schrader N. Fischer K. Theis K. Mendel R.R. Schwarz G. Kisker C. Structure (Lond.). 2003; 11: 1251-1263Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar). YedY, the molybdenum is coordinated by three sulfur two from the of the molybdopterin with a of The sulfur ligand is of to the YedY, a of the of our it is not to the nature of additional to the molybdenum for both sulfur and oxygen of of both oxo and for coordination of the molybdenum oxo group the with of for the of the However, to the presence of from a to be from our we the of the atom as it can be with the typical for an oxo group and with an it and the or for a and a bond to have in the eukaryotic molybdopterin enzymes, with two oxo groups the molybdenum in the A. sulfite oxidase N. Fischer K. Theis K. Mendel R.R. Schwarz G. Kisker C. Structure (Lond.). 2003; 11: 1251-1263Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar) of and one oxo group and one to the substrate the molybdenum of and in the chicken oxidase structure (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar). YedY, the of the conserved is within from one of the oxo and the of and are within from the oxygen pocket to the represents the only likely for substrate a The proposed pocket is by and which for by or for a substrate or substrate the active site The the atom of the molybdenum coordination sphere and is within to the groups of and to the nature of the we of that known to be within our and in our YedY structure the additional with and and and The and not into the and with the the and with a of the that YedY to chicken liver sulfite oxidase (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar) with as is no for sulfite binding in the active site in the structure (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar) ligand and in an a of the enzyme with substrate binding the of YedY The the presence of additional to the molybdenum with and The with Science. PubMed Scopus Google Scholar). of tungsten-substituted YedY the of is in of the substrate binding of YedY and structural that the in substrate two enzymes and YedY the of strictly conserved residues of and eukaryotic sulfite oxidases and in a with the in the structure (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar). to a one of in the sulfite oxidase the to in to to a sulfite oxidase that identified in Garrett R.M. C. Kisker C. Rajagopalan K.V. 2002; PubMed Scopus Google Scholar, 2002; PubMed Scopus Google Scholar, R.M. A. Rajagopalan K.V. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). that the presence of an this is not only for the of the site but is for an the and the oxidized molybdenum C. G. Rajagopalan K.V. Enemark J.H. 2003; PubMed Scopus Google Scholar). YedY, the to in and the side chains of and in YedY the as and in the side of a within the substrate binding pocket of YedY, an with as and sulfite is a in with the one of the oxygen in reductase J. G. R. J. Biol. PubMed Scopus Google Scholar) and in Me2SO reductase J. Huber R. Schindelin H. Kisker C. J. J. 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Full Text Full Text PDF PubMed Scopus Google Scholar) as an and the in and YedY activity as a a to the of J.H. 1996; PubMed Scopus Google Scholar). YedY not show any activity as a sulfite oxidase. YedY functions as a reductase for substrates and However, reductase from E. coli J.H. 1996; PubMed Scopus Google Scholar), YedY is not to as more substrates for molybdopterin as or the substrate binding pocket of YedY are in with our that the enzyme as a reductase rather than a sulfite oxidase. We that the activity are in the presence of 1 to in the in our structure is in the of is to the active site in our YedY is to as Me2SO and which are substrates of Me2SO and and in with a of as a substrate the overall architecture of YedY and eukaryotic sulfite our data YedY an activity as a a that is in keeping with the catalytic residues we in the YedY active kinetic activity for the of are as 1 The are as in a new and of are very to of molybdenum N. A. The of the Scholar). et al. S. Bennett B. J.M. J. Biol. 2000; PubMed Scopus Google Scholar) showed that reductase from is of the of Me2SO with molybdenum or in the active the molybdenum and and the that both in enzymes by the E. and E. Scholar), we the of for molybdenum in YedY by to the to a of YedY in the with two to that in the form. are with a of of from the of the structure of YedY is very to the structure of YedY with a in of from the of have the pterin cofactor with the coordinated by three sulfur the of all the can be with suggesting that tungsten-substituted pterin is into the The YedY and YedY is the of the to in the active site to the metal the by to and to to the in The of ligand in the active site does not to the nature of the substrate binding pocket with the majority of residues a to that in However, we of by in some of the active site in the the of the and the tungsten-substituted YedY structure to than that of YedY we no to the two oxo groups the our analysis of the tungsten-substituted a of reductase activity with from reductase as Me2SO reductase from R. and reductase from E. coli, which have to be or more active is for molybdenum S. Bennett B. J.M. J. Biol. 2000; PubMed Scopus Google Scholar, J. R. G. 1999; PubMed Scopus Google Scholar). The YedY and enzymes is that the metal is coordinated by two pterin rather than in coordination for the of catalytic activity for tungsten-substituted YedY, as it is that the the the potential of the metal in to a in (1Hille R. Trends Biochem. Sci. 2002; 27: 360-367Abstract Full Text Full Text PDF PubMed Scopus (358) Google Scholar). analysis of the tungsten-substituted forms of single enzymes as be to verify the different coordination in enzymes in by the with an the catalytic subunit of the oxidoreductase YedYZ from E. coli, is characterized by the presence of one molybdopterin-type cofactor and is not conjugated by an additional YedY and its orthologues are in a variety of Gram-negative and than structural analysis the residues involved in molybdopterin in the metal coordination and in the substrate binding pocket are strictly conserved the family of bacterial overall YedY is to that of the eukaryotic (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar), and our data further the molybdenum cofactor is likely to have the in both enzymes with two oxygen as the and of the metal However, our kinetic data show that the overall YedY does not show sulfite oxidase are in with the structural of the substrate binding pocket in our YedY YedY the binding pocket of sulfite binding in (3Kisker C. Schindelin H. Pacheco A. Wehbi W.A. Garrett R.M. Rajagopalan K.V. Enemark J.H. Rees D.C. Cell. 1997; 91: 973-983Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar), by three conserved and contains a conserved and residues more in keeping with the active site of the distinct bacterial reductases Me2SO and YedY and its orthologues represent a new type of bacterial reductase in Gram-negative bacteria. our the architecture in the distinct and eukaryotic sulfite and the prokaryotic reductases represent a more molybdoenzyme than We and the and the U. S. of for to the in this We for with and analysis.

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