1
|
Hortschansky P, Ando E, Tuppatsch K, Arikawa H, Kobayashi T, Kato M, Haas H, Brakhage AA. Deciphering the combinatorial DNA-binding code of the CCAAT-binding complex and the iron-regulatory basic region leucine zipper (bZIP) transcription factor HapX. J Biol Chem 2015; 290:6058-70. [PMID: 25589790 DOI: 10.1074/jbc.m114.628677] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heterotrimeric CCAAT-binding complex (CBC) is evolutionarily conserved in eukaryotic organisms, including fungi, plants, and mammals. The CBC consists of three subunits, which are named in the filamentous fungus Aspergillus nidulans HapB, HapC, and HapE. HapX, a fourth CBC subunit, was identified exclusively in fungi, except for Saccharomyces cerevisiae and the closely related Saccharomycotina species. The CBC-HapX complex acts as the master regulator of iron homeostasis. HapX belongs to the class of basic region leucine zipper transcription factors. We demonstrated that the CBC and HapX bind cooperatively to bipartite DNA motifs with a general HapX/CBC/DNA 2:1:1 stoichiometry in a class of genes that are repressed by HapX-CBC in A. nidulans during iron limitation. This combinatorial binding mode requires protein-protein interaction between the N-terminal domain of HapE and the N-terminal CBC binding domain of HapX as well as sequence-specific DNA binding of both the CBC and HapX. Initial binding of the CBC to CCAAT boxes is mandatory for DNA recognition of HapX. HapX specifically targets the minimal motif 5'-GAT-3', which is located at a distance of 11-12 bp downstream of the respective CCAAT box. Single nucleotide substitutions at the 5'- and 3'-end of the GAT motif as well as different spacing between the CBC and HapX DNA-binding sites revealed a remarkable promiscuous DNA-recognition mode of HapX. This flexible DNA-binding code may have evolved as a mechanism for fine-tuning the transcriptional activity of CBC-HapX at distinct target promoters.
Collapse
Affiliation(s)
- Peter Hortschansky
- From the Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, D-07745 Jena, Germany
| | - Eriko Ando
- the Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Katja Tuppatsch
- From the Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, D-07745 Jena, Germany
| | - Hisashi Arikawa
- the Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Tetsuo Kobayashi
- the Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Masashi Kato
- the Faculty of Agriculture, Meijo University, Shiogama-guchi 1-501, Nagoya 468-8502, Japan
| | - Hubertus Haas
- the Division of Molecular Biology, Biocenter, Innsbruck Medical University, A-6020 Innsbruck, Austria, and
| | - Axel A Brakhage
- From the Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, D-07745 Jena, Germany, the Department of Microbiology and Molecular Biology, Institute for Microbiology, Friedrich Schiller University, D-07743 Jena, Germany
| |
Collapse
|
2
|
Thön M, Al Abdallah Q, Hortschansky P, Scharf DH, Eisendle M, Haas H, Brakhage AA. The CCAAT-binding complex coordinates the oxidative stress response in eukaryotes. Nucleic Acids Res 2009; 38:1098-113. [PMID: 19965775 PMCID: PMC2831313 DOI: 10.1093/nar/gkp1091] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The heterotrimeric CCAAT-binding complex is evolutionary conserved in eukaryotic organisms. The corresponding Aspergillus nidulans CCAAT- binding factor (AnCF) consists of the subunits HapB, HapC and HapE. All of the three subunits are necessary for DNA binding. Here, we demonstrate that AnCF senses the redox status of the cell via oxidative modification of thiol groups within the histone fold motif of HapC. Mutational and in vitro interaction analyses revealed that two of these cysteine residues are indispensable for stable HapC/HapE subcomplex formation and high-affinity DNA binding of AnCF. Oxidized HapC is unable to participate in AnCF assembly and localizes in the cytoplasm, but can be recycled by the thioredoxin system in vitro and in vivo. Furthermore, deletion of the hapC gene led to an impaired oxidative stress response. Therefore, the central transcription factor AnCF is regulated at the post-transcriptional level by the redox status of the cell serving for a coordinated activation and deactivation of antioxidative defense mechanisms including the specific transcriptional activator NapA, production of enzymes such as catalase, thioredoxin or peroxiredoxin, and maintenance of a distinct glutathione homeostasis. The underlying fine-tuned mechanism very likely represents a general feature of the CCAAT-binding complexes in eukaryotes.
Collapse
Affiliation(s)
- Marcel Thön
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstrasse 11a, D-07745 Jena, Germany
| | | | | | | | | | | | | |
Collapse
|
3
|
Goda H, Nagase T, Tanoue S, Sugiyama J, Steidl S, Tüncher A, Kobayashi T, Tsukagoshi N, Brakhage AA, Kato M. Nuclear translocation of the heterotrimeric CCAAT binding factor of Aspergillus oryzae is dependent on two redundant localising signals in a single subunit. Arch Microbiol 2005; 184:93-100. [PMID: 16163515 DOI: 10.1007/s00203-005-0014-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 05/02/2005] [Accepted: 05/30/2005] [Indexed: 10/25/2022]
Abstract
The CCAAT-binding complex in the Aspergillus species, also known as the Hap complex, consists of at least three subunits, namely HapB, HapC and HapE. Each Hap subunit contains an evolutionary conserved core domain. Recently, we have found that the HapC and HapE subunits do not carry a nuclear localisation signal. Furthermore, when in complex with HapB, they are transported into the nucleus via a 'piggy back mechanism' in A. nidulans. To extend our findings to other filamentous fungi, we examined the nuclear localisation of the A. oryzae Hap subunits by analysing several GFP fusion proteins with these Hap subunits in the hap deletion strains of A. nidulans. The nuclear translocation of the A. oryzae complex was found to be dependent on two redundant localising signals in HapB.
Collapse
Affiliation(s)
- Hideya Goda
- Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|