6o12

From Proteopedia

Jump to: navigation, search

E. coli cysteine desulfurase SufS H123A

Structural highlights

6o12 is a 1 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 2.05Å
Ligands:CL, PLP
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

SUFS_ECOLI Cysteine desulfurases mobilize the sulfur from L-cysteine to yield L-alanine, an essential step in sulfur metabolism for biosynthesis of a variety of sulfur-containing biomolecules. Component of the suf operon, which is activated and required under specific conditions such as oxidative stress and iron limitation. Acts as a potent selenocysteine lyase in vitro, that mobilizes selenium from L-selenocysteine. Selenocysteine lyase activity is however unsure in vivo.[1] [2] [3] [4] [5]

Publication Abstract from PubMed

Iron-sulfur (Fe-S) clusters are necessary for the proper functioning of numerous metalloproteins. Fe-S cluster (Isc) and sulfur utilization factor (Suf) pathways are the key biosynthetic routes responsible for generating these Fe-S cluster prosthetic groups in Escherichia coli Whereas Isc dominates under normal conditions, Suf takes over during periods of iron depletion and oxidative stress. Sulfur acquisition via these systems relies on the ability to remove sulfur from free cysteine using a cysteine desulfurase mechanism. In the Suf pathway, the dimeric SufS protein uses the cofactor pyridoxal-5'-phosphate (PLP) to abstract sulfur from free cysteine, resulting in the production of alanine and persulfide. Despite much progress, the stepwise mechanism by which this PLP-dependent enzyme operates remains unclear. Here, using rapid-mixing kinetics in conjunction with X-ray crystallography, we analyzed the pre-steady state kinetics of this process while assigning early intermediates of the mechanism. We employed H123A and C364A SufS variants to trap Cys-aldimine and Cys-ketimine intermediates of the cysteine desulfurase reaction, enabling direct observations of these intermediates and associated conformational changes of the SufS active site. Of note, we propose that Cys-364 is essential for positioning the Cys-aldimine for Calpha deprotonation, His-123 acts to protonate the Ala-eneamine intermediate, and Arg-56 facilitates catalysis by hydrogen bonding with the sulfhydryl of Cys-aldimine. Our results, along with previous SufS structural findings, suggest a detailed model of the SufS-catalyzed reaction from Cys binding to C-S bond formation and indicate that Arg-56, His-123, and Cys-364 are critical SufS residues in this C-S bond cleavage pathway.

Direct observation of intermediates in the SufS cysteine desulfurase reaction reveals functional roles of conserved active-site residues.,Blahut M, Wise CE, Bruno MR, Dong G, Makris TM, Frantom PA, Dunkle JA, Outten FW J Biol Chem. 2019 Jun 27. pii: RA119.009471. doi: 10.1074/jbc.RA119.009471. PMID:31248989[6]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

Loading citation details..
Citations
No citations found

See Also

References

  1. Lacourciere GM, Mihara H, Kurihara T, Esaki N, Stadtman TC. Escherichia coli NifS-like proteins provide selenium in the pathway for the biosynthesis of selenophosphate. J Biol Chem. 2000 Aug 4;275(31):23769-73. PMID:10829016 doi:10.1074/jbc.M000926200
  2. Takahashi Y, Tokumoto U. A third bacterial system for the assembly of iron-sulfur clusters with homologs in archaea and plastids. J Biol Chem. 2002 Aug 9;277(32):28380-3. Epub 2002 Jun 27. PMID:12089140 doi:http://dx.doi.org/10.1074/jbc.C200365200
  3. Mihara H, Kato S, Lacourciere GM, Stadtman TC, Kennedy RA, Kurihara T, Tokumoto U, Takahashi Y, Esaki N. The iscS gene is essential for the biosynthesis of 2-selenouridine in tRNA and the selenocysteine-containing formate dehydrogenase H. Proc Natl Acad Sci U S A. 2002 May 14;99(10):6679-83. Epub 2002 May 7. PMID:11997471 doi:http://dx.doi.org/10.1073/pnas.102176099
  4. Loiseau L, Ollagnier-de-Choudens S, Nachin L, Fontecave M, Barras F. Biogenesis of Fe-S cluster by the bacterial Suf system: SufS and SufE form a new type of cysteine desulfurase. J Biol Chem. 2003 Oct 3;278(40):38352-9. Epub 2003 Jul 21. PMID:12876288 doi:http://dx.doi.org/10.1074/jbc.M305953200
  5. Outten FW, Wood MJ, Munoz FM, Storz G. The SufE protein and the SufBCD complex enhance SufS cysteine desulfurase activity as part of a sulfur transfer pathway for Fe-S cluster assembly in Escherichia coli. J Biol Chem. 2003 Nov 14;278(46):45713-9. Epub 2003 Aug 26. PMID:12941942 doi:http://dx.doi.org/10.1074/jbc.M308004200
  6. Blahut M, Wise CE, Bruno MR, Dong G, Makris TM, Frantom PA, Dunkle JA, Outten FW. Direct observation of intermediates in the SufS cysteine desulfurase reaction reveals functional roles of conserved active-site residues. J Biol Chem. 2019 Jun 27. pii: RA119.009471. doi: 10.1074/jbc.RA119.009471. PMID:31248989 doi:http://dx.doi.org/10.1074/jbc.RA119.009471

Contents


PDB ID 6o12

Drag the structure with the mouse to rotate

Proteopedia Page Contributors and Editors (what is this?)

OCA

Personal tools