BANF1
Domain
Has a helix-hairpin-helix (HhH) structural motif conserved among proteins that bind non-specifically to DNA.
LEM domain proteins bind centrally on the BAF dimer.
Function
Non-specific DNA-binding protein that plays key roles in mitotic nuclear reassembly, chromatin organization, DNA damage response, gene expression and intrinsic immunity against foreign DNA (PubMed:10908652, PubMed:11792822, PubMed:12163470, PubMed:18005698, PubMed:25991860, PubMed:28841419, PubMed:31796734, PubMed:32792394). Contains two non-specific double-stranded DNA (dsDNA)-binding sites which promote DNA cross-bridging (PubMed:9465049). Plays a key role in nuclear membrane reformation at the end of mitosis by driving formation of a single nucleus in a spindle-independent manner (PubMed:28841419). Transiently cross-bridges anaphase chromosomes via its ability to bridge distant DNA sites, leading to the formation of a dense chromatin network at the chromosome ensemble surface that limits membranes to the surface (PubMed:28841419). Also acts as a negative regulator of innate immune activation by restricting CGAS activity toward self-DNA upon acute loss of nuclear membrane integrity (PubMed:32792394). Outcompetes CGAS for DNA-binding, thereby preventing CGAS activation and subsequent damaging autoinflammatory responses (PubMed:32792394). Also involved in DNA damage response: interacts with PARP1 in response to oxidative stress, thereby inhibiting the ADP-ribosyltransferase activity of PARP1 (PubMed:31796734). Involved in the recognition of exogenous dsDNA in the cytosol: associates with exogenous dsDNA immediately after its appearance in the cytosol at endosome breakdown and is required to avoid autophagy (PubMed:25991860). In case of poxvirus infection, has an antiviral activity by blocking viral DNA replication (PubMed:18005698).
(Microbial infection) Exploited by retroviruses for inhibiting self-destructing autointegration of retroviral DNA, thereby promoting integration of viral DNA into the host chromosome (PubMed:11005805, PubMed:16680152, PubMed:9465049). EMD and BAF are cooperative cofactors of HIV-1 infection (PubMed:16680152). Association of EMD with the viral DNA requires the presence of BAF and viral integrase (PubMed:16680152). The association of viral DNA with chromatin requires the presence of BAF and EMD (PubMed:16680152).
Involvement in disease
Nestor-Guillermo progeria syndrome
NGPS
An atypical progeroid syndrome characterized by normal development in the first years of life, later followed by the emergence of generalized lipoatrophy, severe osteoporosis, and marked osteolysis. The atrophic facial subcutaneous fat pad and the marked osteolysis of the maxilla and mandible result in a typical pseudosenile facial appearance with micrognathia, prominent subcutaneous venous patterning, a convex nasal ridge, and proptosis. Cognitive development is completely normal. Patients do not have cardiovascular dysfunction, atherosclerosis, or metabolic anomalies.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
Ser-4 is the major site of phosphorylation as compared to Thr-2 and Thr-3. Phosphorylation on Thr-2; Thr-3 and Ser-4 disrupts its ability to bind DNA and reduces its ability to bind LEM domain-containing proteins. Non phosphorylated BAF seems to enhance binding between EMD and LMNA. Dephosphorylated by protein phosphatase 2A (PP2A) following interaction with ANKLE2/LEM4 during mitotic exit, leading to mitotic nuclear envelope reassembly.
(Microbial infection) Phosphorylated by poxvirus B1 kinase (VPK1) on serine and threonine residues, leading to BANF1 relocalization to the cytoplasm, loss of dimerization and impaired DNA binding activity.
(Microbial infection) Phosphorylated at the N-terminus by vaccinia virus (VacV) B1 kinase, leading to BANF1 relocalization to the cytoplasm, loss of dimerization and impaired DNA binding activity (PubMed:16495336, PubMed:24600006). Hyperphosphorylation is linked to the loss of ability to suppress vaccinia virus replication (PubMed:24600006).
Sequence Similarities
Belongs to the BAF family.
Tissue Specificity
Widely expressed. Expressed in colon, brain, heart, kidney, liver, lung, ovary, pancreas, placenta, prostate, skeletal muscle, small intestine, spleen and testis. Not detected in thymus and peripheral blood leukocytes.
Cellular localization
- Nucleus
- Chromosome
- Nucleus envelope
- Cytoplasm
- Significantly enriched at the nuclear inner membrane, diffusely throughout the nucleus during interphase and concentrated at the chromosomes during the M-phase (PubMed:16495336, PubMed:24600006). The phosphorylated form (by VRK1) shows a cytoplasmic localization whereas the unphosphorylated form locates almost exclusively in the nucleus (PubMed:16495336, PubMed:24600006). May be included in HIV-1 virions via its interaction with viral GAG polyprotein (PubMed:14645565).
Alternative names
BAF, BCRG1, BANF1, Barrier-to-autointegration factor, Breakpoint cluster region protein 1