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In vitro activation of apo-aconitase using a [4Fe-4S] cluster-loaded form of the IscU [Fe-S] cluster scaffolding protein.
Biochemistry. 2007 Jun 12; 46(23):6812-21.B

Abstract

Genetic experiments have established that IscU is involved in maturation of [Fe-S] proteins that require either [2Fe-2S] or [4Fe-4S] clusters for their biological activities. Biochemical studies have also shown that one [2Fe-2S] cluster can be assembled in vitro within each subunit of the IscU homodimer and that these clusters can be reductively coupled to form a single [4Fe-4S] cluster. In the present work, it is shown that the [4Fe-4S] cluster-loaded form of A. vinelandii IscU, but not the [2Fe-2S] cluster-loaded form, can be used for intact cluster transfer to an apo form of A. vinelandii aconitase A, a member of the monomeric dehydratase family of proteins that requires a [4Fe-4S] cluster for enzymatic activity. The rate of [4Fe-4S] cluster transfer from IscU to apo-aconitase A was not affected by the presence of the HscA/HscB co-chaperone system and MgATP. However, an altered form of a [4Fe-4S] cluster-containing IscU, having the highly conserved aspartate-39 residue substituted with alanine, is an effective inhibitor of wild-type [4Fe-4S] cluster-loaded IscU-directed activation of apo-aconitase A. In contrast, neither the clusterless form of IscU nor the [2Fe-2S] cluster-loaded form of IscU is an effective inhibitor of IscU-directed apo-aconitase A activation. These results are interpreted to indicate that the [2Fe-2S] and [4Fe-4S] cluster-loaded forms of IscU adopt different conformations that provide specificity with respect to the maturation of [2Fe-2S] and [4Fe-4S] centers in proteins.

Authors+Show Affiliations

Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

17506526

Citation

Unciuleac, Mihaela-Carmen, et al. "In Vitro Activation of Apo-aconitase Using a [4Fe-4S] Cluster-loaded Form of the IscU [Fe-S] Cluster Scaffolding Protein." Biochemistry, vol. 46, no. 23, 2007, pp. 6812-21.
Unciuleac MC, Chandramouli K, Naik S, et al. In vitro activation of apo-aconitase using a [4Fe-4S] cluster-loaded form of the IscU [Fe-S] cluster scaffolding protein. Biochemistry. 2007;46(23):6812-21.
Unciuleac, M. C., Chandramouli, K., Naik, S., Mayer, S., Huynh, B. H., Johnson, M. K., & Dean, D. R. (2007). In vitro activation of apo-aconitase using a [4Fe-4S] cluster-loaded form of the IscU [Fe-S] cluster scaffolding protein. Biochemistry, 46(23), 6812-21.
Unciuleac MC, et al. In Vitro Activation of Apo-aconitase Using a [4Fe-4S] Cluster-loaded Form of the IscU [Fe-S] Cluster Scaffolding Protein. Biochemistry. 2007 Jun 12;46(23):6812-21. PubMed PMID: 17506526.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - In vitro activation of apo-aconitase using a [4Fe-4S] cluster-loaded form of the IscU [Fe-S] cluster scaffolding protein. AU - Unciuleac,Mihaela-Carmen, AU - Chandramouli,Kala, AU - Naik,Sunil, AU - Mayer,Suzanne, AU - Huynh,Boi Hanh, AU - Johnson,Michael K, AU - Dean,Dennis R, Y1 - 2007/05/17/ PY - 2007/5/18/pubmed PY - 2007/9/25/medline PY - 2007/5/18/entrez SP - 6812 EP - 21 JF - Biochemistry JO - Biochemistry VL - 46 IS - 23 N2 - Genetic experiments have established that IscU is involved in maturation of [Fe-S] proteins that require either [2Fe-2S] or [4Fe-4S] clusters for their biological activities. Biochemical studies have also shown that one [2Fe-2S] cluster can be assembled in vitro within each subunit of the IscU homodimer and that these clusters can be reductively coupled to form a single [4Fe-4S] cluster. In the present work, it is shown that the [4Fe-4S] cluster-loaded form of A. vinelandii IscU, but not the [2Fe-2S] cluster-loaded form, can be used for intact cluster transfer to an apo form of A. vinelandii aconitase A, a member of the monomeric dehydratase family of proteins that requires a [4Fe-4S] cluster for enzymatic activity. The rate of [4Fe-4S] cluster transfer from IscU to apo-aconitase A was not affected by the presence of the HscA/HscB co-chaperone system and MgATP. However, an altered form of a [4Fe-4S] cluster-containing IscU, having the highly conserved aspartate-39 residue substituted with alanine, is an effective inhibitor of wild-type [4Fe-4S] cluster-loaded IscU-directed activation of apo-aconitase A. In contrast, neither the clusterless form of IscU nor the [2Fe-2S] cluster-loaded form of IscU is an effective inhibitor of IscU-directed apo-aconitase A activation. These results are interpreted to indicate that the [2Fe-2S] and [4Fe-4S] cluster-loaded forms of IscU adopt different conformations that provide specificity with respect to the maturation of [2Fe-2S] and [4Fe-4S] centers in proteins. SN - 0006-2960 UR - https://www.unboundmedicine.com/medline/citation/17506526/In_vitro_activation_of_apo_aconitase_using_a_[4Fe_4S]_cluster_loaded_form_of_the_IscU_[Fe_S]_cluster_scaffolding_protein_ L2 - https://doi.org/10.1021/bi6026665 DB - PRIME DP - Unbound Medicine ER -