MAC1/YMR021C Summary Help

Standard Name MAC1 1
Systematic Name YMR021C
Alias CUA1
Feature Type ORF, Verified
Description Copper-sensing transcription factor; involved in regulation of genes required for high affinity copper transport; required for regulation of yeast copper genes in response to DNA-damaging agents; undergoes changes in redox state in response to changing levels of copper or MMS (1, 2, 3 and see Summary Paragraph)
Name Description Metal binding ACtivator 1
Chromosomal Location
ChrXIII:318418 to 317165 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All MAC1 GO evidence and references
  View Computational GO annotations for MAC1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Targets 60 genes
Regulators 4 genes
Classical genetics
Large-scale survey
52 total interaction(s) for 45 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 3
  • Affinity Capture-RNA: 1
  • Affinity Capture-Western: 1
  • Biochemical Activity: 1
  • FRET: 1
  • Two-hybrid: 9

Genetic Interactions
  • Dosage Rescue: 1
  • Negative Genetic: 15
  • Phenotypic Enhancement: 1
  • Phenotypic Suppression: 2
  • Positive Genetic: 4
  • Synthetic Growth Defect: 9
  • Synthetic Lethality: 2
  • Synthetic Rescue: 2

Expression Summary
Length (a.a.) 417
Molecular Weight (Da) 46,516
Isoelectric Point (pI) 7.06
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXIII:318418 to 317165 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1254 318418..317165 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000004623

MAC1 encodes a transcription factor ("Metal-binding activator") that regulates the expression of genes involved in copper homeostasis (1). In response to low copper levels, Mac1p induces expression of the copper transporters Ctr1p (2, 4, 5, 6, 7) and Ctr3p (4, 6, 7), the (known or putative) cell-surface metal reductases Fre1p (1, 2, 4, 5, 6, 7, 8, 9, 10, 11) and Fre7p (7, 10, 11) and two uncharacterized ORF's, YFR055W and YJL217W (7). FRE1 is expressed early and FRE2 is expressed late during copper depletion; in Mac1p-depleted cells, FRE1 expression persists for longer and FRE2 expression begins earlier (9). Mac1p is also responsible for the H2O2-induced transcription of CTT1 (1). Copper inhibits the activity of Mac1p (2, 8, 9).

Cells lacking active Mac1p are viable but copper-deficient, respiratory deficient, and sensitive to heat, hydrogen peroxide, cadmium, zinc, and lead; normal growth and respiration can be restored by supplementing the growth medium with copper or iron (1). Mac1p-depleted cells are also sensitive to oxytetracycline and doxycycline (12) and resistant to the anti-cancer drug cisplatin (13). Since iron uptake depends heavily on copper uptake, cells lacking active Mac1p also exhibit a secondary iron deficiency (8, 14). A hypermorphic mutation, MAC1up1, is resistant to inhibition by copper (8) and causes increased copper uptake and copper hypersensitivity (1, 6, 15).

Mac1p binds a copper-response element ("CuRE"), TTTGC(T/G)C(A/G), in the promoters of target genes (4, 5, 10, 11). Two CuREs are required for induction by Mac1p, and the spacing between them is important (10). Mac1p binds single CuREs as a monomer in vitro, but binds synergistically to promoters with two or more CuREs in vivo (16, 17). CuRE binding requires phosphorylation of Mac1p and is disrupted by Cu(I) or Ag(I). Mac1p also requires copper in order to bind CuREs, indicating that Mac1p detects both a minimum and a maximum allowable copper concentration (18); therefore, Mac1p is often referred to as the "nutritional" copper sensor, in contrast to the "toxic" copper sensor Cup2p (also known as Ace1p), which is activated when copper levels become excessive (6).

Mac1p has two nuclear localization signals, and the protein is found in the nucleus in both copper-starved and copper-replete cells (1, 19, 20). The N-terminal DNA-binding domain recognizes CuREs and binds two Zn(II) ions, which are required for DNA-binding activity (16, 17, 19, 20). Mac1p also has two cysteine-rich domains, referred to as Rep I and Rep II, that bind a total of eight copper ions (2, 19, 20). (Ultraviolet irradiation causes Mac1p to emit orange light, indicating that these are Cu(I) ions (19).) The constitutive MAC1up1 mutation lies in Rep I (2, 20) and the mutant protein binds only four or five copper ions (19); mutation of other residues in Rep I, but not Rep II, also leads to constitutive Mac1p activity (20, 21). Rep I binds four Cu(I) ions in a trigonal configuration similar to one found in Cup2p (22). Rep II is a copper-dependent transactivation domain (23). In the absence of copper, a C-terminal D helix mediates dimerization with other Mac1p molecules to form ternary activation complexes on the promoters of target genes (20). Nutritional copper levels stabilize Mac1p but cause an intramolecular reaction in which the D helix binds the DNA-binding domain and prevents binding to CuREs, abrogating gene activation (19, 20). Mac1up1p is more stable than the wild-type protein during copper depletion, but is not stabilized by copper (19). Mac1p is degraded at high copper concentrations, but MAC1up1p is resistant (15).

Mac1p also indirectly mediates the degradation of Ctr1p in high copper concentrations; the DNA-binding domain of Mac1p is required, and, as stated above, Mac1p is not found outside the nucleus, suggesting that Mac1p activates the transcription of genes required for Ctr1p degradation (24).

Last updated: 2005-08-24 Contact SGD

References cited on this page View Complete Literature Guide for MAC1
1) Jungmann J, et al.  (1993) MAC1, a nuclear regulatory protein related to Cu-dependent transcription factors is involved in Cu/Fe utilization and stress resistance in yeast. EMBO J 12(13):5051-6
2) Graden JA and Winge DR  (1997) Copper-mediated repression of the activation domain in the yeast Mac1p transcription factor. Proc Natl Acad Sci U S A 94(11):5550-5
3) Dong K, et al.  (2013) The yeast copper response is regulated by DNA damage. Mol Cell Biol 33(20):4041-50
4) Labbe S, et al.  (1997) Copper-specific transcriptional repression of yeast genes encoding critical components in the copper transport pathway. J Biol Chem 272(25):15951-8
5) Yamaguchi-Iwai Y, et al.  (1997) Homeostatic regulation of copper uptake in yeast via direct binding of MAC1 protein to upstream regulatory sequences of FRE1 and CTR1. J Biol Chem 272(28):17711-8
6) Pena MM, et al.  (1998) Dynamic regulation of copper uptake and detoxification genes in Saccharomyces cerevisiae. Mol Cell Biol 18(5):2514-23
7) Gross C, et al.  (2000) Identification of the copper regulon in Saccharomyces cerevisiae by DNA microarrays. J Biol Chem 275(41):32310-6
8) Hassett R and Kosman DJ  (1995) Evidence for Cu(II) reduction as a component of copper uptake by Saccharomyces cerevisiae. J Biol Chem 270(1):128-34
9) Georgatsou E, et al.  (1997) The yeast Fre1p/Fre2p cupric reductases facilitate copper uptake and are regulated by the copper-modulated Mac1p activator. J Biol Chem 272(21):13786-92
10) Martins LJ, et al.  (1998) Metalloregulation of FRE1 and FRE2 homologs in Saccharomyces cerevisiae. J Biol Chem 273(37):23716-21
11) Georgatsou E and Alexandraki D  (1999) Regulated expression of the Saccharomyces cerevisiae Fre1p/Fre2p Fe/Cu reductase related genes. Yeast 15(7):573-84
12) Angrave FE and Avery SV  (2001) Antioxidant functions required for insusceptibility of Saccharomyces cerevisiae to tetracycline antibiotics. Antimicrob Agents Chemother 45(10):2939-42
13) Ishida S, et al.  (2002) Uptake of the anticancer drug cisplatin mediated by the copper transporter Ctr1 in yeast and mammals. Proc Natl Acad Sci U S A 99(22):14298-302
14) De Freitas JM, et al.  (2004) Exploratory and confirmatory gene expression profiling of mac1Delta. J Biol Chem 279(6):4450-8
15) Zhu Z, et al.  (1998) Copper differentially regulates the activity and degradation of yeast Mac1 transcription factor. J Biol Chem 273(3):1277-80
16) Jensen LT, et al.  (1998) Mapping of the DNA binding domain of the copper-responsive transcription factor Mac1 from Saccharomyces cerevisiae. J Biol Chem 273(37):23805-11
17) Joshi A, et al.  (1999) Evidence for (Mac1p)2.DNA ternary complex formation in Mac1p-dependent transactivation at the CTR1 promoter. J Biol Chem 274(1):218-26
18) Heredia J, et al.  (2001) Phosphorylation and Cu+ coordination-dependent DNA binding of the transcription factor Mac1p in the regulation of copper transport. J Biol Chem 276(12):8793-7
19) Jensen LT and Winge DR  (1998) Identification of a copper-induced intramolecular interaction in the transcription factor Mac1 from Saccharomyces cerevisiae. EMBO J 17(18):5400-8
20) Serpe M, et al.  (1999) Structure-function analysis of the protein-binding domains of Mac1p, a copper-dependent transcriptional activator of copper uptake in Saccharomyces cerevisiae. J Biol Chem 274(41):29211-9
21) Keller G, et al.  (2000) Functional independence of the two cysteine-rich activation domains in the yeast Mac1 transcription factor. J Biol Chem 275(38):29193-9
22) Brown KR, et al.  (2002) Structures of the cuprous-thiolate clusters of the Mac1 and Ace1 transcriptional activators. Biochemistry 41(20):6469-76
23) Voutsina A, et al.  (2001) The second cysteine-rich domain of Mac1p is a potent transactivator that modulates DNA binding efficiency and functionality of the protein. FEBS Lett 494(1-2):38-43
24) Yonkovich J, et al.  (2002) Copper ion-sensing transcription factor Mac1p post-translationally controls the degradation of its target gene product Ctr1p. J Biol Chem 277(27):23981-4