IKI1/YHR187W Summary Help

Standard Name IKI1 1
Systematic Name YHR187W
Alias TOT5 2 , ELP5 3 , 4 , HAP2
Feature Type ORF, Verified
Description Subunit of hexameric RecA-like ATPase Elp456 Elongator subcomplex; which is required for modification of wobble nucleosides in tRNA; iki1 mutations confer resistance to the K. lactis toxin zymocin (5, 6, 7, 8 and see Summary Paragraph)
Name Description Insensitive to KIller toxin 1
Chromosomal Location
ChrVIII:480990 to 481919 | ORF Map | GBrowse
Gene Ontology Annotations All IKI1 GO evidence and references
  View Computational GO annotations for IKI1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 5 genes
Classical genetics
Large-scale survey
204 total interaction(s) for 119 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 28
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 32
  • Co-crystal Structure: 1
  • Co-purification: 5
  • PCA: 4
  • Reconstituted Complex: 2
  • Two-hybrid: 2

Genetic Interactions
  • Dosage Growth Defect: 1
  • Dosage Rescue: 9
  • Negative Genetic: 86
  • Phenotypic Enhancement: 4
  • Positive Genetic: 25
  • Synthetic Growth Defect: 1
  • Synthetic Rescue: 2

Expression Summary
Length (a.a.) 309
Molecular Weight (Da) 35,219
Isoelectric Point (pI) 4.55
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrVIII:480990 to 481919 | ORF Map | GBrowse
Last Update Coordinates: 2005-11-07 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..930 480990..481919 2005-11-07 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 SGDIDS000001230

Iki1p/Elp5p is part of the six-subunit Elongator complex, which is a major histone acetyltransferase component of the RNA polymerase II holoenzyme responsible for transcriptional elongation (9, 2, 10). Elongator contains two discrete subcomplexes, one consisting of Iki3p/Elp1p, Elp2p, and Elp3p, and the other consisting of Elp4p, Iki1p/Elp5p, and Elp6p (3, 4). Elongator binds to both naked and nucleosomal DNA, can acetylate both core histones and nucleosomal substrates, and plays a role in chromatin remodeling (11, 12). Its activity is directed specifically toward the amino-terminal tails of histone H3 and H4, with the predominant acetylation sites being lysine-14 of histone H3 and lysine-8 of histone H4 (12). Within Elongator, Iki1p/Elp5p interacts specifically with Elp2p and Kti12p (13).

Of the six Elongator subunits, only Iki1p/Elp5p is essential for growth, and deletion of the other individual subunits causes significantly altered mRNA expression levels for many genes (4). Disruption of the Elongator complex confers resistance to the Kluyveromyces lactis zymotoxin (6), and a reduced sensitivity to the Pichia inositovora toxin (14).

Last updated: 2004-05-12 Contact SGD

References cited on this page View Complete Literature Guide for IKI1
1) Yajima H, et al.  (1997) Characterization of IKI1 and IKI3 genes conferring pGKL killer sensitivity on Saccharomyces cerevisiae. Biosci Biotechnol Biochem 61(4):704-9
2) Frohloff F, et al.  (2001) Saccharomyces cerevisiae Elongator mutations confer resistance to the Kluyveromyces lactis zymocin. EMBO J 20(8):1993-2003
3) Winkler GS, et al.  (2001) RNA polymerase II elongator holoenzyme is composed of two discrete subcomplexes. J Biol Chem 276(35):32743-9
4) Krogan NJ and Greenblatt JF  (2001) Characterization of a six-subunit holo-elongator complex required for the regulated expression of a group of genes in Saccharomyces cerevisiae. Mol Cell Biol 21(23):8203-12
5) Kishida M, et al.  (1996) Isolation and genetic characterization of pGKL killer-insensitive mutants (iki) from Saccharomyces cerevisiae. Biosci Biotechnol Biochem 60(5):798-801
6) Frohloff F, et al.  (2003) Subunit communications crucial for the functional integrity of the yeast RNA polymerase II elongator (gamma-toxin target (TOT)) complex. J Biol Chem 278(2):956-61
7) Esberg A, et al.  (2006) Elevated levels of two tRNA species bypass the requirement for elongator complex in transcription and exocytosis. Mol Cell 24(1):139-48
8) Glatt S, et al.  (2012) The Elongator subcomplex Elp456 is a hexameric RecA-like ATPase.LID - 10.1038/nsmb.2234 [doi] Nat Struct Mol Biol ()
9) Wittschieben BO, et al.  (1999) A novel histone acetyltransferase is an integral subunit of elongating RNA polymerase II holoenzyme. Mol Cell 4(1):123-8
10) Jablonowski D, et al.  (2001) Kluyveromyces lactis zymocin mode of action is linked to RNA polymerase II function via Elongator. Mol Microbiol 42(4):1095-105
11) Wittschieben BO, et al.  (2000) Overlapping roles for the histone acetyltransferase activities of SAGA and elongator in vivo. EMBO J 19(12):3060-8
12) Winkler GS, et al.  (2002) Elongator is a histone H3 and H4 acetyltransferase important for normal histone acetylation levels in vivo. Proc Natl Acad Sci U S A 99(6):3517-22
13) Fichtner L, et al.  (2002) Protein interactions within Saccharomyces cerevisiae Elongator, a complex essential for Kluyveromyces lactis zymocicity. Mol Microbiol 45(3):817-26
14) Klassen R and Meinhardt F  (2003) Structural and functional analysis of the killer element pPin1-3 from Pichia inositovora. Mol Genet Genomics 270(2):190-9