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J. Biol. Chem., Vol. 277, Issue 19, 16936-16940, May 10, 2002
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,
,, and**
From the Cancer Research UK DNA Repair Enzyme Group,
Section of Structural Biology, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, United Kingdom, the
§ Department of Biology, Darwin Building, University College
London, Gower Street, London WC1E 6BT, United Kingdom, the
¶ Department of Chemistry, Kings College London, The Strand,
London WC2R 2LS, United Kingdom, and the Institute of Medical
Radiobiology, University of Zurich, August Forel Strasse 7, 8008 Zurich, Switzerland
Received for publication, January 22, 2002
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ABSTRACT |
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 TOP
 ABSTRACT
 INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
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The 25-kDa Family 4 uracil-DNA glycosylase
(UDG) from Pyrobaculum aerophilum has been expressed and
purified in large quantities for structural analysis. In the
process we observed it to be colored and subsequently found that it
contained iron. Here we demonstrate that P. aerophilum UDG has an iron-sulfur center with the EPR characteristics typical of a 4Fe4S high potential iron protein. Interestingly, it does not share any sequence similarity with the
classic iron-sulfur proteins, although four cysteines (which are
strongly conserved in the thermophilic members of Family 4 UDGs)
may represent the metal coordinating residues. The conservation of
these residues in other members of the family suggest that 4Fe4S
clusters are a common feature. Although 4Fe4S clusters have been
observed previously in Nth/MutY DNA repair enzymes, this is the first
observation of such a feature in the UDG structural superfamily.
Similar to the Nth/MutY enzymes, the Family 4 UDG centers
probably play a structural rather than a catalytic role.
Uracil-DNA glycosylases are ubiquitous DNA repair enzymes
responsible for the excision of uracil bases from DNA as the first step
in a base excision repair pathway. Uracil arises in DNA either as a
result of the hydrolytic deamination of cytosine residues in G:C base
pairs (1) or from incorporation of deoxyuridine monophosphate (instead
of thymidine monophosphate) opposite adenine during DNA replication
(2). If left uncorrected the former process would cause G:C to A:T
transition mutations (1), whereas the latter may result in the
disruption of specific regulatory DNA-protein interactions (3).
Hyperthermophilic organisms are at especially high risk of DNA damage
by cytosine deamination, which is significantly enhanced by elevated
temperature (4). Because hyperthermophiles do not exhibit any greater
susceptibility to this type of damage they presumably possess more
effective repair enzymes (5). However, despite the detection of
UDG1 activity in several
hyperthermophiles (6) no sequences homologous to the archetypal
Escherichia coli ung-encoded enzyme were initially apparent
in archaeal genomes. Subsequently, UDGs were identified in
hyperthermophilic Eubacteria and Archaea (7-9) with more
obvious homology to a second family of uracil base excision repair
enzymes typified by the human thymine DNA glycosylase (TDG) (10) and the bacterial MUG (11). These G:T/U mismatch-specific enzymes (Family 2) are structurally and mechanistically related to the UNG-type UDGs (Family 1) (12, 13), and they unite the UNG-type and thermophile enzymes (Family 4) into a uracil-DNA glycosylase superfamily (14).
Pyrobaculum aerophilum is a hyperthermophilic archaeon
isolated from a boiling marine water hole and growing optimally at 100 °C and pH 7.0 (15). A fosmid-based genomic map of the 1.7-Mb P. aerophilum genome was constructed and used to identify
474 putative genes (16), but no homologues of the UNG or MUG/TDG UDG
families were initially identified. Following the identification of
Tm-UDG (a novel UDG weakly related to E. coli MUG) in the thermophilic eubacterium Thermotoga
maritima, a homologous open reading frame was identified in
P. aerophilum encoding a new protein (designated Pa-UDG) with significant homology to Tm-UDG (9).
Here we show Pa-UDG to be an iron-sulfur protein with the
characteristics of a 4Fe4S high potential iron protein center (HiPIP).
Comparison of amino acid sequences and molecular modeling identified
residues constituting the iron-sulfur cluster, suggesting that this is a common (although not universal) structural feature of the Family 4 UDGs.
Expression and Purification of Pa-UDG--
Pa-UDG was
expressed in E. coli strain BL21(DE3) pLysS from
plasmid pET28-Pa-UDG essentially as described (9) with an
N-terminal His6 tag. The cell pellet was resuspended in
buffer A (50 mM Tris, pH 8, 100 mM NaCl, 10%
glycerol), supplemented with Complete EDTA-free protease inhibitor
mixture (Roche Molecular Biochemicals), and stored at Spectroscopy--
Ultraviolet/visible spectroscopy was carried
out using a Shimadzu UV-2401PC recording spectrophotometer. Continuous
wave electron paramagnetic resonance spectra were obtained using a JEOL
RE1X spectrometer equipped with an Oxford Instruments liquid helium cryostat. Samples were analyzed as prepared following reduction with
sodium dithionite and oxidation with potassium ferricyanide.
The His6-tagged Pa-UDG was overexpressed in
BL21(DE3) cells using a pET28c(+)-Pa-UDG construct
(9). The protein was purified from the cell lysate by heat treatment
and immobilized metal-ion chromatography and cation exchange
chromatography to give an essentially pure sample migrating with an
approximate molecular mass of 25 kDa on SDS-PAGE (Fig.
1a), whereas MALDI-TOF mass
spectrometry gave a more precise mass of 24.248 kDa (Fig.
1b). Both results were consistent with the theoretical mass
for His-tagged Pa-UDG (24.628 kDa). N-terminal analysis of
the purified protein prior to and following removal of the
His6 tag by digestion with thrombin confirmed its identity
as Pa-UDG. Uracil-DNA glycosylase activity of the purified
protein at 70 °C was confirmed as described (6).
INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
EXPERIMENTAL PROCEDURES
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
20 °C. Cells
were lysed by thawing followed by a brief sonication on an ice/ethanol
slurry (15 × 9-s bursts with 9-s cooling periods between bursts).
The lysate was clarified by centrifugation at 50,000 × g, and the supernatant was then incubated for 5 min at
80 °C to denature and precipitate the thermolabile E. coli proteins. The sample was cooled on ice, clarified by
centrifugation at 50,000 × g, and then loaded onto a
5-ml Ni-nitrilotriacetic acid (Ni-NTA) column pre-equilibrated in
buffer A. The flow-through was discarded, as was a subsequent 10-column
volume wash of buffer A supplemented with 10 mM imidazole.
Pa-UDG was eluted in 5-column volumes of buffer A
supplemented with 300 mM imidazole. The sample fractions
were identified in the first instance by SDS-PAGE analysis (15%
acrylamide) and subsequently by the yellow color. Sample fractions were
pooled, and volume was reduced (if required) to 10 ml by concentration
in a Centriprep 20 spin concentrator (5-kDa cut off) (Amicon). The
sample buffer was then exchanged using a desalting column
pre-equilibrated in buffer B (50 mM sodium phosphate, pH
7.5, 10 mM NaCl, 10% glycerol, 1 mM
dithiothreitol, Complete EDTA-free protease inhibitors). A cation
exchange step was then used to complete the purification. During
initial preparations an HR5/5 Mono S column (Amersham Biosciences) was
chosen, but during later preparations an XK26/10 column packed with
SP-Sepharose fast flow resin (Amersham Biosciences) was selected
instead. Flow rates were used as recommended by the manufacturer for
the column selected. In both cases the sample was applied to a column
already equilibrated in buffer B. Both the flow-through and a 5-column volume of buffer B wash were discarded. Bound protein was eluted via a
linear NaCl gradient (10-500 mM) over 20-column volumes. The purified protein fractions were pooled and concentrated (as described above) and then transferred into buffer A supplemented with 1 mM dithiothreitol using a PD10 desalting column (Bio-Rad). Purity was assessed by Coomassie Blue-stained SDS-PAGE (15%
acrylamide), and the protein was stored in aliquots at 70 °C.
RESULTS
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
View larger version (48K):
[in a new window]
Fig. 1.
Expression and purification of
Pa-UDG. a, SDS-polyacrylamide gel
showing fractions from various stages of purification. Lane
1, soluble fraction of E. coli cell lysate; lane
2, after heat treatment; lane 3, unbound material from
Ni-NTA resin; lane 4, 10 mM imidazole wash;
lane 5, 300 mM imidazole eluate; lane
6, after cation exchange chromatography. The protein after step 6 is >95% pure. b, MALDI-TOF mass spectrum of purified
Pa-UDG (lane 6 above). The estimated peak mass of
24,248 is consistent with the calculated mass of 24,628 for the
iron-free protein.
The pure protein was dialyzed against a minimal buffer of 50 mM Tris-HCl, pH 8.0, 100 mM NaCl, and 1 mM dithiothreitol for concentration and subsequent
crystallographic analysis. The protein was highly soluble and could be
concentrated to >30 mg ml
1. Unexpectedly, diluted
Pa-UDG (~1 mg ml1) was observed to be yellow
in color, and this color intensified to dark olive and eventually brown
as the sample was concentrated by ultrafiltration. The retention and
concentration of the color against a 5-kDa cutoff membrane suggested a
high molecular mass protein-associated chromophore rather than a small
molecule contaminant. Consistent with this observation, an adsorption
spectrum of the concentrated protein displayed a broad peak around
370-400 nm (in addition to the normal absorption peaks around 280 nm)
caused by side chains of aromatic amino acid residues (Fig.
2). Absorption peaks in the 370-400-nm
region can result from a variety of common biological chromophores
ranging from carotenes to porphyrins and iron-sulfur clusters. To
determine whether any metals were present in the purified protein the
buffered sample was lyophilized and analyzed by inductively coupled
plasma-atomic emission spectroscopy, which confirmed the presence of
iron within the protein with an estimated stoichiometry of ~3 iron
atoms per mol of protein.
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To ascertain the nature of the iron present in purified
Pa-UDG we recorded continuous wave electron paramagnetic
resonance spectra of protein prepared using a Mono S cation exchange
step in the first instance (Fig. 3). The
EPR spectra of the enzyme clearly demonstrated the presence of
iron-sulfur centers in the sample. As prepared, the enzyme showed a
weak spectrum characteristic of oxidized 3Fe4S centers with g values at
approximately 2.02. Upon reduction with sodium dithionite, this was
replaced by a weak ferredoxin-like spectrum with peaks at g values of
approximately 2.06, 1.95, and 1.85. Upon oxidation with potassium
ferricyanide a much stronger signal was observed, partly indicating an
increase in the oxidized 3Fe4S center but also showing strong signals
at g values of 2.12 and 2.04, which is characteristic of an oxidized 4Fe4S high potential iron protein center and demonstrates the presence
of both 3Fe and 4Fe centers in the preparation.
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When a Mono S column was used as the final purification step the
Pa-UDG eluted essentially as a single peak, although the chromatogram suggested that there actually may have been two peaks present (which had not been fully resolved). When the Mono S column was
replaced by an SP-Sepharose fast flow column Pa-UDG
reproducibly eluted as two distinct peaks (Fig.
4a) designated as species 1 and 2. Each peak contained a pure colored protein that migrated in
SDS-PAGE with a molecular weight consistent with Pa-UDG
(Fig. 4b) and was confirmed as such by MALDI-TOF mass
spectrometry and Edman N-terminal sequencing in both cases (data not
shown). The EPR spectra of the two peaks were very similar (Fig.
4c). Both samples contained a 4Fe4S HiPIP center giving
large signals in the oxidized state but little signal as prepared or in
the reduced state. However, species 2 contained a small amount of the
3Fe center observed in previously described preparations, whereas species 1 did not.
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DISCUSSION |
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TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
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Taken together the UV-visible, atomic absorption, and electron paramagnetic resonance spectroscopic data all point to the presence of an integral cuboidal iron-sulfur cluster of the 4Fe4S HiPIP type in the Family 4 UDG from P. aerophilum. Depending on the methodology used in the purification of Pa-UDG, the 3Fe4S and 4Fe4S clusters may co-exist and may be interconvertible as in other iron-sulfur proteins such as aconitase (17, 18), although the 3Fe centers may be the result of damage or partial denaturation during the purification process. Resolution of two apparently compositionally identical 4Fe4S species in an ion exchange column suggests that multiple oxidation states with different net charges may be possible also. Cuboidal iron-sulfur clusters have been observed previously in DNA repair enzymes of the MutY/Nth/Ogg structural superfamily (19) such as the eubacterial endonuclease III (20) and the archaeal Pa-MIG (also identified in P. aerophilum) (21). However, to our knowledge Pa-UDG is the first example of such a feature in the uracil-DNA glycosylase structural superfamily (14).
Location of Cluster-Ligand Residues--
Iron-sulfur clusters of
the HiPIP type are usually attached via tetrahedrally directed bonds
from the iron atoms to the S
atoms of four cysteine residues in the
polypeptide chain. The Pa-UDG sequence contains six cysteine
residues of which four are totally conserved in the characterized
T. maritima and Archeoglobus fulgidus Family 4 UDGs (7, 8) and in many homologous archaeal and eubacterial (putative)
UDG sequences (Fig. 5). These four cysteine residues are not totally conserved throughout Family 4 homologues, the first and third being replaced by aromatic residues in
Rickettsia, for example, nor are they restricted to
hyperthermophiles, being present in Family 4 UDG homologues from
spirochaetes, mycobacteria, Clostridia, and
Deinococcus radiodurans.
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In previously described HiPIP-type cuboidal iron-sulfur proteins the sequence distribution of cysteine ligands varies considerably, and consensus can be obtained only within protein families. The putative ligands in the Family 4 UDGs conform to a pattern, Cys-X2-Cys-Xn-CysX(14-17)-Cys, where n ranges from 70 to 100. This is quite distinct from the Nth/MutY DNA repair enzymes, which show a much more localized consensus pattern, Cys-X4-Pro-X-Cys-X2Cys-X(6-8)-Cys, and it does not resemble any known distributions of cysteine ligands in other iron-sulfur proteins characterized to date. If these conserved cysteines act as ligands as we suggest, then Pa-UDG must be able to fold so that the N-terminal Cys-X2-Cys motif comes within sufficiently close proximity to the central Cys-X(14-17)-Cys motif to bond to the iron atoms at the corners of the cuboidal 4Fe4S cluster.
To date no structure for a Family 4 UDG has been reported. However,
sequence threading and profile analysis techniques suggest that Family
4 UDGs will have a similar overall fold to the bacterial Family 2 MUG
enzymes (14). Mapping the Pa-UDG sequence onto the crystal
structure of E. coli MUG (12, 13) locates the central pair
of putative iron-sulfur cluster ligands on the surface-exposed face of
helix four and the loop that precedes it (Fig.
6a). Cysteine residues at
these positions (corresponding approximately to residues 72 and 87 in
the MUG structure) would be well located to provide two ligands for a
4Fe4S cluster. The N-terminal CX2C motif occurs in a segment of the Pa-UDG sequence that precedes the N
terminus of MUG, and topologically equivalent residues therefore cannot be located in the known MUG structure. However, the N terminus of MUG
is on the same face of the protein as the residues corresponding to the
central cysteine pair in Pa-UDG. The N-terminal pair of putative 4Fe4S ligand residues occurs 8 and 11 residues upstream of the
residue in the Pa-UDG sequence that corresponds to the N
terminus of MUG and would certainly be on the same face of the protein
as the central pair of putative cluster ligands. Although the E. coli MUG protein lacks residues corresponding to this segment of
Pa-UDG, the more distantly related Family 1 UDGs do possess corresponding segments of sequence. In Family 1 UDG structures this
segment forms a turn and a preceding helix that lies over the surface
carrying the topological equivalents of MUG residues 71 and 87. If a
similar structure were present in Pa-UDG it would comfortably deliver the N-terminal CX2C motif
into a position suitable for providing the remaining pair of ligands
for the iron-sulfur cluster. (Fig. 6b).
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Functional Role of an Iron-Sulfur Cluster--
Iron-sulfur
clusters occur in a wide range of enzymes primarily as redox active
co-factors participating directly in electron-transfer catalytic
mechanisms. However, cuboidal 4Fe4S clusters have also been identified
in non-redox enzymes, most notably in the Nth/MutY family of DNA repair
enzymes (20, 22, 23). A variety of biochemical and biophysical studies
suggests that the 4Fe4S cluster in these enzymes is not involved
directly in catalysis (24). Instead it functions as a structural
cross-link analogous to disulfide bonds or zinc fingers and nonetheless
contributes to substrate recognition by maintaining the structure of
protein segments involved in DNA interactions (25-27). On the basis of
the structural homology between the Family 4 enzymes and the Family 2 bacterial MUG, the deduced site of the 4Fe4S cluster in
Pa-UDG suggests that it would not participate directly in
glycosylase activity. However, the central pair of putative conserved
cysteine ligands map to the beginning and end of a loop segment in MUG
that is involved in contacts with the DNA phosphate backbone (Fig.
6c) (12, 13) so that, similar to the Nth/MutY enzymes, the
4Fe4S cluster would probably play a role in substrate recognition but
not catalysis. Determination of the precise role of the cuboidal 4Fe4S
cluster in Family 4 uracil-DNA glycosylases must await the results of structural and mutagenesis studies, which are ongoing.
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ACKNOWLEDGEMENTS |
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We thank Renos Savva, Tracey Barrett, and Bernard Connolly for useful discussions, Angela Paul for assistance with sequencing and mass spectrometry, and Emile Brule for assistance with atomic absorption spectroscopy.
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FOOTNOTES |
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* This work was supported by the Cancer Research UK (to L. H. P.). The generous financial support of the UBS (to A. A. S. and J. J.) is also gratefully acknowledged.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
** To whom correspondence should be addressed. Tel.: 44-207-970-6046; Fax: 44-207-970-6051; E-mail: l.pearl@icr.ac.uk.
Published, JBC Papers in Press, February 27, 2002, DOI 10.1074/jbc.M200668200
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ABBREVIATIONS |
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The abbreviations used are: UDG, uracil DNA glycosylase; TDG, thymine DNA glycosylase; HiPIP, high potential iron-sulfur protein center; Nth, endonuclease III; MALDI-TOF, matrix-assisted laser desorption/ionization-time of flight; MUG, mismatch-specific uracil-DNA glycosylase.
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REFERENCES |
|---|
|
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
|
|---|
| 1. |
Lindahl, T.
(1993)
Nature
362,
709-715[CrossRef][Medline]
[Order article via Infotrieve] |
| 2. |
Tye, B.-K.,
Chien, J.,
Lehman, I. R.,
Duncan, B. K.,
and Warner, H. R.
(1978)
Proc. Natl. Acad. Sci. U. S. A.
75,
233-237 |
| 3. |
Focher, F.,
Verri, A.,
Verzeletti, S.,
Mazzarello, P.,
and Spadari, S.
(1992)
Chromosoma
102,
S67-S71[CrossRef][Medline]
[Order article via Infotrieve] |
| 4. |
Lindahl, T.,
and Nyberg, B.
(1974)
Biochemistry
13,
3405-3410[CrossRef][Medline]
[Order article via Infotrieve] |
| 5. |
Jacobs, K. L.,
and Grogan, D. W.
(1997)
J. Bacteriol.
179,
3298-3303 |
| 6. |
Koulis, A.,
Cowan, D. A.,
Pearl, L. H.,
and Savva, R.
(1996)
FEMS Microbiol. Lett.
143,
267-271[CrossRef][Medline]
[Order article via Infotrieve] |
| 7. |
Sandigursky, M.,
and Franklin, W. A.
(1999)
Curr. Biol.
9,
531-534[CrossRef][Medline]
[Order article via Infotrieve] |
| 8. |
Sandigursky, M.,
and Franklin, W. A.
(2000)
J. Biol. Chem.
275,
19146-19149 |
| 9. |
Sartori, A. A.,
Schar, P.,
Fitz-Gibbon, S.,
Miller, J. H.,
and Jiricny, J.
(2001)
J. Biol. Chem.
276,
29979-29986 |
| 10. |
Nedderman, P.,
and Jiricny, J.
(1993)
J. Biol. Chem.
268,
21218-21224 |
| 11. |
Gallinari, P.,
and Jiricny, J.
(1996)
Nature
383,
735-738[CrossRef][Medline]
[Order article via Infotrieve] |
| 12. |
Barrett, T. E.,
Savva, R.,
Panayotou, G.,
Barlow, T.,
Brown, T.,
Jiricny, J.,
and Pearl, L. H.
(1998)
Cell
92,
117-129[CrossRef][Medline]
[Order article via Infotrieve] |
| 13. |
Barrett, T. E.,
Schärer, O. D.,
Savva, R.,
Brown, T.,
Jiricny, J.,
Verdine, G. L.,
and Pearl, L. H.
(1999)
EMBO J.
18,
6599-6609[CrossRef][Medline]
[Order article via Infotrieve] |
| 14. |
Pearl, L. H.
(2000)
Mutat. Res. DNA Repair
460,
165-181[Medline]
[Order article via Infotrieve] |
| 15. |
Volkl, P.,
Huber, R.,
Drobner, E.,
Rachel, R.,
Burggraf, S.,
Trincone, A.,
and Stetter, K. O.
(1993)
Appl. Environ. Microbiol.
59,
2918-2926 |
| 16. |
Fitz-Gibbon, S.,
Choi, A. J.,
Miller, J. H.,
Stetter, K. O.,
Simon, M. I.,
Swanson, R.,
and Kim, U. J.
(1997)
Extremophiles
1,
36-51[CrossRef][Medline]
[Order article via Infotrieve] |
| 17. |
Kennedy, M. C.,
and Bienert, H.
(1983)
J. Biol. Chem.
263,
8194-8198 |
| 18. |
Kennedy, M. C.,
Emptage, M. H.,
Dreyer, J.-L.,
and Bienert, H.
(1983)
J. Biol. Chem.
258,
11098-11105 |
| 19. |
Nash, H. M.,
Bruner, S. D.,
Scharer, O. D.,
Kawate, T.,
Addona, T. A.,
Sponner, E.,
Lane, W. S.,
and Verdine, G. L.
(1996)
Curr. Biol.
6,
968-980[CrossRef][Medline]
[Order article via Infotrieve] |
| 20. |
Cunningham, R. P.,
Asahara, H.,
Bank, J. F.,
Scholes, C. P.,
Salerno, J. C.,
Surerus, K.,
Munck, E.,
McCracken, J.,
Peisach, J.,
and Emptage, M. H.
(1989)
Biochemistry
28,
4450-4455[CrossRef][Medline]
[Order article via Infotrieve] |
| 21. |
Yang, H.,
Fitz-Gibbon, S.,
Marcotte, E. M.,
Tai, J. H.,
Hyman, E. C.,
and Miller, J. H.
(2000)
J. Bacteriol.
182,
1272-1279 |
| 22. |
Michaels, M. L.,
Pham, L.,
Ngheim, Y.,
Cruz, C.,
and Miller, J. H.
(1990)
Nucleic Acids Res.
18,
3841-3845 |
| 23. |
Thayer, M. M.,
Ahern, H.,
Xing, D. X.,
Cunningham, R. P.,
and Tainer, J. A.
(1995)
EMBO J.
14,
4108-4120[Medline]
[Order article via Infotrieve] |
| 24. |
Fu, W. G.,
Ohandley, S.,
Cunningham, R. P.,
and Johnson, M. K.
(1992)
J. Biol. Chem.
267,
16135-16137 |
| 25. |
Porello, S. L.,
Cannon, M. J.,
and David, S. S.
(1998)
Biochemistry
37,
6465-6475[CrossRef][Medline]
[Order article via Infotrieve] |
| 26. |
Golinelli, M. P.,
Chmiel, N. H.,
and David, S. S.
(1999)
Biochemistry
38,
6997-7007[CrossRef][Medline]
[Order article via Infotrieve] |
| 27. |
Kuo, C. F.,
McRee, D. E.,
Fisher, C. L.,
O'Handley, S. F.,
Cunningham, R. P.,
and Tainer, J. A.
(1992)
Science
258,
434-440 |
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-helices) and dark arrows (
-strands). The N- and
C-terminal motifs that form the active sites in the two families are
boxed, and the cysteine residues proposed to act as ligands
for the iron-sulfur cluster are shown in reverse. Segments of the amino
acid sequences occurring significantly before the N terminus or
extending significantly beyond the C terminus of E. coli MUG
are not shown.
