Replication protein A 32 interacts through a similar binding interface with TIPIN, XPA, and UNG2.
The 32kDa subunit of replication protein A (RPA32) is involved in various DNA repair systems such as nucleotide excision repair, base excision repair, and homologous recombination. In these processes, RPA32 interacts with different binding partners via its C-terminal domain (RPA32C; residues 172-270). It has been reported recently that RPA32C also interacts with TIPIN during the intra-S checkpoint. To determine the significance of the interaction of RPA32C with TIPIN, we have examined the interaction mode using NMR spectroscopy and an in silico modeling approach. Here, we show that TIPIN(185-218), which shares high sequence similarity with XPA(10-43) and UNG2(56-89), is less ordered in the free state and then forms a longer alpha-helix upon binding to RPA32C. The binding interface between TIPIN(185-218) and RPA32C is similar to those of XPA and UNG2, but its mode of interaction is different. The results suggest that RPA32 is an exchange point for multiple proteins involved in DNA repair, homologous recombination, and checkpoint processes and that it binds to different partners with comparable binding affinity using a single site.
Ali
Seikh Imtiaz
SI
Department of Chemistry, KAIST, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea.
Shin
Jae-Sun
JS
Bae
Sung-Hun
SH
Kim
Byoungkook
B
Choi
Byong-Seok
BS
D000595:Amino Acid Sequence; D001665:Binding Sites; D002942:Circular Dichroism; D045647:DNA Glycosylases / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D051716:Replication Protein A / Q000737:chemistry / Q000378:metabolism*; D055672:Static Electricity; D013499:Surface Properties; D051760:Xeroderma Pigmentosum Group A Protein / Q000378:metabolism*
D009687:Nuclear Proteins; D011994:Recombinant Proteins; D051716:Replication Protein A; D051760:Xeroderma Pigmentosum Group A Protein; D045647:DNA Glycosylases