AHA1/YDR214W Summary Help

Standard Name AHA1 1
Systematic Name YDR214W
Feature Type ORF, Verified
Description Co-chaperone that binds Hsp82p and activates its ATPase activity; plays a role in determining prion variants; similar to Hch1p; expression is regulated by stresses such as heat shock; protein abundance increases in response to DNA replication stress (1, 2, 3, 4 and see Summary Paragraph)
Name Description Activator of Heat shock protein 90 ATPase 1
Chromosomal Location
ChrIV:892875 to 893927 | ORF Map | GBrowse
Gene Ontology Annotations All AHA1 GO evidence and references
  View Computational GO annotations for AHA1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 16 genes
Classical genetics
Large-scale survey
128 total interaction(s) for 86 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 50
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 11
  • Co-crystal Structure: 2
  • FRET: 1
  • PCA: 3
  • Reconstituted Complex: 4
  • Two-hybrid: 11

Genetic Interactions
  • Dosage Growth Defect: 1
  • Negative Genetic: 36
  • Phenotypic Suppression: 1
  • Positive Genetic: 2
  • Synthetic Growth Defect: 2
  • Synthetic Rescue: 1

Expression Summary
Length (a.a.) 350
Molecular Weight (Da) 39,435
Isoelectric Point (pI) 7.52
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrIV:892875 to 893927 | ORF Map | GBrowse
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1053 892875..893927 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 SGDIDS000002622

AHA1 and the closely related gene HCH1 encode cochaperones that regulate the activity of members of the HSP90 family (Hsp82p and Hsc82p in S. cerevisiae; 1, 5). The presence of Aha1p and Hch1p, although not required for ATP hydrolysis, is able to stimulate the ATPase activity of Hsp82p/Hsc82p five- to twelve-fold (1, 5). The N-terminal domain of Aha1p, which is equivalent to the entirety of Hch1p, binds to the middle domain of Hsp82p/Hsc82p and promotes a conformational change in the chaperone proteins that enhances their ability to bind ATP (5, 6, 2). Overexpression of Aha1p stimulates the ATPase activity of Hsp82p/Hsc82p, restores the cochaperone interactions and compensates for the functional defects of a phosphomimetic mutation in HSP82/HSC82 (7).

Expression of AHA1 is induced by stress, a process mediated by the transcriptional activator Hsf1p which binds to three heat shock elements in the AHA1 promoter (1). AHA1 is not required for growth under optimal conditions but is essential for survival in cells under stress (1, 5).

Aha1p is a highly conserved protein with similar proteins identified in S. pombe, worms, plants, flies, mice, and humans (5).

Last updated: 2012-12-13 Contact SGD

References cited on this page View Complete Literature Guide for AHA1
1) Panaretou B, et al.  (2002) Activation of the ATPase activity of hsp90 by the stress-regulated cochaperone aha1. Mol Cell 10(6):1307-18
2) Siligardi G, et al.  (2004) Co-chaperone regulation of conformational switching in the Hsp90 ATPase cycle. J Biol Chem 279(50):51989-98
3) Tkach JM, et al.  (2012) Dissecting DNA damage response pathways by analysing protein localization and abundance changes during DNA replication stress. Nat Cell Biol 14(9):966-76
4) Lancaster DL, et al.  (2013) Chaperone proteins select and maintain [PIN+] prion conformations in Saccharomyces cerevisiae. J Biol Chem 288(2):1266-76
5) Lotz GP, et al.  (2003) Aha1 binds to the middle domain of Hsp90, contributes to client protein activation, and stimulates the ATPase activity of the molecular chaperone. J Biol Chem 278(19):17228-35
6) Meyer P, et al.  (2004) Structural basis for recruitment of the ATPase activator Aha1 to the Hsp90 chaperone machinery. EMBO J 23(6):1402-10
7) Mollapour M, et al.  (2011) Threonine 22 phosphorylation attenuates hsp90 interaction with cochaperones and affects its chaperone activity. Mol Cell 41(6):672-81