PMID- 10639125
OWN - NLM
STAT- MEDLINE
DCOM- 20000302
LR  - 20190501
IS  - 0027-8424 (Print)
IS  - 0027-8424 (Linking)
VI  - 97
IP  - 2
DP  - 2000 Jan 18
TI  - NifS-directed assembly of a transient [2Fe-2S] cluster within the NifU protein.
PG  - 599-604
AB  - The NifS and NifU proteins from Azotobacter vinelandii are required for the full 
      activation of nitrogenase. NifS is a homodimeric cysteine desulfurase that
      supplies the inorganic sulfide necessary for formation of the Fe-S clusters
      contained within the nitrogenase component proteins. NifU has been suggested to
      complement NifS either by mobilizing the Fe necessary for nitrogenase Fe-S
      cluster formation or by providing an intermediate Fe-S cluster assembly site. As 
      isolated, the homodimeric NifU protein contains one [2Fe-2S](2+, +) cluster per
      subunit, which is referred to as the permanent cluster. In this report, we show
      that NifU is able to interact with NifS and that a second, transient [2Fe-2S]
      cluster can be assembled within NifU in vitro when incubated in the presence of
      ferric ion, L-cysteine, and catalytic amounts of NifS. Approximately one
      transient [2Fe-2S] cluster is assembled per homodimer. The transient [2Fe-2S]
      cluster species is labile and rapidly released on reduction. We propose that
      transient [2Fe-2S] cluster units are formed on NifU and then released to supply
      the inorganic iron and sulfur necessary for maturation of the nitrogenase
      component proteins. The role of the permanent [2Fe-2S] clusters contained within 
      NifU is not yet known, but they could have a redox function involving either the 
      formation or release of transient [2Fe-2S] cluster units assembled on NifU.
      Because homologs to both NifU and NifS, respectively designated IscU and IscS,
      are found in non-nitrogen fixing organisms, it is possible that the function of
      NifU proposed here could represent a general mechanism for the maturation of Fe-S
      cluster-containing proteins.
FAU - Yuvaniyama, P
AU  - Yuvaniyama P
AD  - Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061-0346, USA.
FAU - Agar, J N
AU  - Agar JN
FAU - Cash, V L
AU  - Cash VL
FAU - Johnson, M K
AU  - Johnson MK
FAU - Dean, D R
AU  - Dean DR
LA  - eng
GR  - GM51962/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Proc Natl Acad Sci U S A
JT  - Proceedings of the National Academy of Sciences of the United States of America
JID - 7505876
RN  - 0 (Bacterial Proteins)
RN  - 0 (Iron-Sulfur Proteins)
RN  - 0 (Macromolecular Substances)
RN  - 0 (NifU protein, Bacteria)
RN  - 0 (nifS protein, Bacteria)
RN  - E1UOL152H7 (Iron)
SB  - IM
MH  - Amino Acid Substitution
MH  - Azotobacter vinelandii/chemistry
MH  - Bacterial Proteins/*chemistry/genetics/isolation & purification
MH  - Iron/chemistry
MH  - Iron-Sulfur Proteins/*chemistry
MH  - Macromolecular Substances
MH  - Oxidation-Reduction
MH  - Spectrophotometry, Ultraviolet
MH  - Spectrum Analysis, Raman
PMC - PMC15376
EDAT- 2000/01/19 09:00
MHDA- 2000/03/04 09:00
CRDT- 2000/01/19 09:00
PHST- 2000/01/19 09:00 [pubmed]
PHST- 2000/03/04 09:00 [medline]
PHST- 2000/01/19 09:00 [entrez]
AID - 10.1073/pnas.97.2.599 [doi]
PST - ppublish
SO  - Proc Natl Acad Sci U S A. 2000 Jan 18;97(2):599-604. doi: 10.1073/pnas.97.2.599.