1ci4
From Proteopedia
THE CRYSTAL STRUCTURE OF HUMAN BARRIER-TO-AUTOINTEGRATION FACTOR (BAF)
Structural highlights
DiseaseBAF_HUMAN Defects in BANF1 are the cause of Nestor-Guillermo progeria syndrome (NGPS) [MIM:614008. NGPS is 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 micrognatia, 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.[1] FunctionBAF_HUMAN Plays fundamental roles in nuclear assembly, chromatin organization, gene expression and gonad development. May potently compress chromatin structure and be involved in membrane recruitment and chromatin decondensation during nuclear assembly. Contains 2 non-specific dsDNA-binding sites which may promote DNA cross-bridging. Exploited by retroviruses for inhibiting self-destructing autointegration of retroviral DNA, thereby promoting integration of viral DNA into the host chromosome. EMD and BAF are cooperative cofactors of HIV-1 infection. Association of EMD with the viral DNA requires the presence of BAF and viral integrase. The association of viral DNA with chromatin requires the presence of BAF and EMD.[2] [3] [4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBarrier-to-autointegration factor (BAF) is a host cell protein that plays a crucial role in retroviral integration. Preintegration complexes (PICs) stripped of BAF lose their normal integration activity, which can be restored by incubation with purified BAF. BAF bridges double-stranded DNA both intra- and intermolecularly in a non-sequence-specific manner, leading to the formation of a nucleoprotein network. BAF also binds to the nuclear protein lamina-associated polypeptide 2 (LAP2), and is localized with chromatin during interphase and mitosis. The crystal structure of homodimeric human BAF has been determined to 1.9 A resolution. The fold of the BAF monomer resembles that of the second domain of RuvA. This comparison revealed the presence of the helix-hairpin-helix (HhH) nonspecific DNA binding motif within BAF. A novel feature of BAF's HhH motif is the occupation of the metal binding site by the epsilon-amino group of Lys 6, providing an alternative means of sequestering positive charge. Mutational analysis corroborates the HhH motif's prominent role in DNA binding and argues against a previously proposed helix-turn-helix (HTH) binding site located in another region of the monomer. A model of BAF bridging DNA via the HhH motif is proposed. Structural basis of DNA bridging by barrier-to-autointegration factor.,Umland TC, Wei SQ, Craigie R, Davies DR Biochemistry. 2000 Aug 8;39(31):9130-8. PMID:10924106[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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