Detailed entry information

Protein Information (annotations from UniProt)

Database IDHIV0002174
UniProt IDQ9H611
Primary gene name(s)PIF1
Synonym gene name(s)C15orf20
Protein nameATP-dependent DNA helicase PIF1
Protein functionDNA-dependent ATPase and 5'-3' DNA helicase required for the maintenance of both mitochondrial and nuclear genome stability. Efficiently unwinds G-quadruplex, G4 DNA structures and forked RNA-DNA hybrids. Resolves G4 structures, preventing replication pausing and double-strand breaks, DSBs at G4 motifs. Involved in the maintenance of telomeric DNA. Inhibits telomere elongation, de novo telomere formation and telomere addition to DSBs via catalytic inhibition of telomerase. Reduces the processivity of telomerase by displacing active telomerase from DNA ends. Releases telomerase by unwinding the short telomerase RNA/telomeric DNA hybrid that is the intermediate in the telomerase reaction. Possesses an intrinsic strand annealing activity. {ECO:0000255|HAMAP-Rule:MF_03176, ECO:0000269|PubMed:16522649, ECO:0000269|PubMed:17172855, ECO:0000269|PubMed:17827721, ECO:0000269|PubMed:18835853, ECO:0000269|PubMed:19700773, ECO:0000269|PubMed:20524933, ECO:0000269|PubMed:23657261}.
Subcellular locationNucleus {ECO:0000255|HAMAP-Rule:MF_03176, ECO:0000269|PubMed:16522649, ECO:0000269|PubMed:17172855, ECO:0000269|PubMed:17827721}.;
SUBCELLULAR LOCATION: Isoform 4: Mitochondrion {ECO:0000255|HAMAP-Rule:MF_03176, ECO:0000269|PubMed:23275553}.
ECO codeClick here for more information.
Amino acid sequence
FASTA format: Q9H611
Gene Ontology
(Biological Process)
Complete annatation
DNA recombination [GO:0006310];
DNA repair [GO:0006281];
G-quadruplex DNA unwinding [GO:0044806];
mitochondrial genome maintenance [GO:0000002];
negative regulation of telomerase activity [GO:0051974];
negative regulation of telomere maintenance via telomerase [GO:0032211];
regulation of telomere maintenance [GO:0032204];
telomere maintenance [GO:0000723]
Gene Ontology
(Molecular Function)
Complete annatation
ATP binding [GO:0005524];
ATP-dependent 5'-3' DNA/RNA helicase activity [GO:0033682];
ATP-dependent 5'-3' DNA helicase activity [GO:0043141];
G-quadruplex DNA binding [GO:0051880];
magnesium ion binding [GO:0000287];
single-stranded DNA-dependent ATP-dependent DNA helicase activity [GO:0017116];
telomerase inhibitor activity [GO:0010521];
telomeric DNA binding [GO:0042162]
Gene Ontology
(Cellular Component)
Complete annatation
mitochondrion [GO:0005739];
nuclear chromosome, telomeric region [GO:0000784];
replication fork [GO:0005657]
Protein-protein interaction123122
Phylogenetic treeQ9H611
HIV replication factor status Zhou et al., Cell. Host. Microbe., 2008
      unknown
Brass et al., Science, 2008
      unknown
Smith et al., J. Immunol, 2010
      unknown
Interferon-stimulated
gene status
Lu et al., J. Virol., 2011
      Folds changes 8h: unknown; Folds changes 16h: unknown; Tested: unknown;
Schoggins JW and Rice CM, Curr. Opin. Virol., 2011
      Targeted viruses: unknown
      Viral life cycle: unknown
      Mechanism related to antiviral activity: unknown
Anti-viral restriction factor Liu et al., Retrovirology, 2011
      unknown (Triplicates)

Gene Expression Profile       top

            Up-regulated;            Down-regulated

For brief introduction to each study, please go to the help page.

Gene expression during HIV latency

(1). Mohammadi et al., PLoS Pathog., 2014

Differentially expressed transcripts (Pairwise) during latency and subsequent viral reactivation using several agents - Primary CD4+ T-cell based model


DMSO: Dimethyl suloxyde (negative control) - 0.0033% final
SAHA: Vorinostat (Histone deacetylase inhibitor) - 0.5 μM
CD3: TCR Stimulation by IL-2+ antiCD3/anti-CD28 antibodies
IL7: Interleukin-7 based stimulation
DISU: Disulfiram (alcohol dehydrogenase inhibitor) - 0.5 μM
AZA: 5-azacytidine (AZA; DNA methylation inhibitor) - 1 μM
Experimental Condition Log2 Fold Change P value Adjusted P value
AZA vs. CD3-0.5040889641498580.4342005108990710.555446452238227
AZA vs. DISU-0.4658666991361150.2323441735320550.818503808132176
AZA vs. IL7-0.1452628416883990.7704435754969430.999311006273513
AZA vs. SAHA-0.6307439943145920.2021598303206310.569812506030889
DISU vs. CD30.03069868845809120.9580717725325460.972982139672276
DISU vs. IL70.3044536727139290.4276078538160790.782556472079664
DISU vs. SAHA-0.1576574390441270.6662423046424330.898517921545065
DMSO vs. AZA0.1956051812049650.6651023851367611
DMSO vs. CD30.6803894567344120.2610010073176970.368197413169876
DMSO vs. DISU0.6533750522622770.03394853116532580.372346699171368
DMSO vs. IL7-0.3336072254731740.4519893701844370.870666975979836
DMSO vs. SAHA-0.8273742368988490.0561676834463050.270001959555283
HIV vs. Mock in Activation0.05472859171868990.9654118568344740.999983755607037
HIV vs. Mock in Latency0.3332656389210720.5082801154958550.999834320637052
IL7 vs. CD30.3668982518074250.569050892663840.689905360365005
SAHA vs. CD3-0.1524762086231160.8119231708634340.865997748242052
SAHA vs. IL7-0.487841495609090.3178233863412120.566430565820221
(2). Iglesias-Ussel et al., J. Virol., 2013

Up and Downregulated transcripts during Latency (Latently infected CD4+ T cells vs Uninfected)- Primary CD4+Tcell based model
Log2 Fold Change P Value
unknown unknown

Gene expression during HIV infection and replication

(1). Imbeault et al., PloS Pathog., 2012

Transcriptomic profiling of HIV-1 infected CD4+ T cells - Primary CD4+ T cells
Experiment type Log2 Fold Change P Value Adjusted P Value
Infected vs. Mock unknown unknown unknown
Infected vs. Bystander unknown unknown unknown
(2). Lefebvre et al., J. Virol., 2011

Transcriptome analysis of T-cell line (Sup T1)
Log2 Fold Change unknown
(3). Li et al., J. Immunol., 2013

Lymphatic tissue
Acute Fold Change Acute P Value Asymt Fold Change Asypt P Value AIDS Fold Change AIDS P Value
unknown unknown unknown unknown unknown unknown
(4). Chang et al., MBio., 2011

Transcriptome analysis of T-cell line (Sup T1)

Derived from Sherrill-Mix et al., BMC Retrovirol., 2015 cross validation
Up-regulated (True) FALSE
(5). Sherrill-Mix et al., BMC Retrovirol., 2015

Deep RNA-seq analysis of primary human T cell infected with low passage HIV isolate HIV89.6 - Primary CD4+ T cell based
Test Status Log2 Fold Change P Value
OK 0.758621 0.000305467
(6). Rotger et al., PLoS Pathog., 2010

Genome-wide mRNA expression of CD4+ T cells from HIV-infected patient
(Genes differentially expressed (at adjusted p<0.01) according to the empirical Bayes approach)
Log2 Fold Change P Value
unknown unknown

Proteomic/Transcriptomics studies indicating differentially expressed genes mediated by HIV

(1). Greenwood et al., Elife, 2016

Activated (CD3/CD28) Primary human CD4+ T cells infected with pNL4-3-dE-EGFP. The table shows the complete (unfiltered) TMT (tandem mass tag)-based proteomic time course dataset
6 h 24 h 48 h 72 h RTi
unknown unknown unknown unknown unknown
(2). Navare et al., Virology, 2012

SUP-T1 cell line
FC-4hpi P-value FC-8hpi P-value FC-20hpi P-value Category
unknown unknown unknown unknown unknown unknown unknown
(3). Hyrcza et al., J. Virolo., 2007

Primary human CD4+ and CD8+ T Cells
Affymetrix Prob ID Fold Change In CD8? Category
unknown unknown unknown unknown

Protein Overview       top

Drug-protein Interaction       (annotations from DrugBank)      top

not found

Protein Secondary Structure       (annotations from PDB)      top

PDB Accession Method Resolution Chain Structure Preview
5FHH X-ray 3.6Å A/B=200-641.

HIV-1 Interaction       (annotations from NCBI HIV-1 Interaction Database)      top

not found

Metabolic/Signalling Pathway       (annotations from KEGG database)      top

Pathway Accession Number Description
not found
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