The role of the GAF and central domains of the transcriptional activator VnfA in Azotobacter vinelandii.
Summary of "The role of the GAF and central domains of the transcriptional activator VnfA in Azotobacter vinelandii."
VnfA is a transcriptional activator required for the expression of the structural genes encoding nitrogenase-2 in Azotobacter vinelandii. VnfA consists of three domains: an N-terminal regulatory domain termed GAF, including a Cys-rich motif, a central domain from the AAA+ family, and a C-terminal domain for DNA binding. Previously, we reported that transcriptionally active VnfA harbored an Fe-S cluster, presumably of the 3Fe-4S type, as a prosthetic group, and the Cys-rich motif were possibly associated with coordination of the Fe-S cluster. In the present work, we have studied the roles of the GAF and central domains in the regulatory function of VnfA using truncated variants: ΔN15(VnfA) and ΔGAF(VnfA) that lack the N-terminal 15 residues and whole GAF domain, respectively, and GAF(VnfA) consisting of only the GAF domain. ΔN15(VnfA) and ΔGAF(VnfA) lost the ability to bind the Fe-S cluster, whereas GAF(VnfA) was still able to bind to the cluster, consistent with the hypothesis that the Cys-rich motif is essential for Fe-S cluster binding. The GAF domain showed an inhibitory effect on the transcriptional activity of VnfA, which was reversed in the presence of the Fe-S cluster, and reactivated upon disassembly of the cluster. The inhibitory activity of the GAF domain acts on the NTPase activity of the central domain, whereas the binding ability of VnfA to DNA was not significantly affected, when VnfA retains its tetrameric conformation. The results imply that a major pathway by which VnfA function is regulated, operates via the control of NTPase activity by the GAF domain. Structured digital abstract: VnfA binds to VnfA by molecular sieving (View Interaction 1, 2).
Affiliation
Department of Chemistry, Graduate School of Science, Nagoya University Graduate School of Bioagricultural Science, Nagoya University Research Center of Materials Science, Nagoya University.
Journal Details
This article was published in the following journal.
Name: The FEBS journal
ISSN: 1742-4658
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21752196
- DOI: http://dx.doi.org/10.1111/j.1742-4658.2011.08245.x
Medical and Biotech [MESH] Definitions
Azotobacter Vinelandii
A species of gram-negative, aerobic bacteria first isolated from soil in Vineland, New Jersey. Ammonium and nitrate are used as nitrogen sources by this bacterium. It is distinguished from other members of its genus by the ability to use rhamnose as a carbon source. (From Bergey's Manual of Determinative Bacteriology, 9th ed)
B-cell-specific Activator Protein
A transcription factor that is essential for CELL DIFFERENTIATION of B-LYMPHOCYTES. It functions both as a transcriptional activator and repressor to mediate B-cell commitment.
Receptors, Urokinase Plasminogen Activator
An extracellular receptor specific for UROKINASE-TYPE PLASMINOGEN ACTIVATOR. It is attached to the cell membrane via a GLYCOSYLPHOSPHATIDYLINOSITOL LINKAGE and plays a role in the co-localization of urokinase-type plasminogen activator with PLASMINOGEN.
Interferon Regulatory Factor-1
An interferon regulatory factor that binds upstream TRANSCRIPTIONAL REGULATORY ELEMENTS in the GENES for INTERFERON-ALPHA and INTERFERON-BETA. It functions as a transcriptional activator for the INTERFERON TYPE I genes.
Maf Transcription Factors, Small
A family of Maf Transcription Factors that lack activation domains. Small Maf proteins function as transcriptional repressors or form heterodimeric complexes to serve as transcriptional coactivators. Small Maf proteins include MafF, MafG, and MafK.
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