Self-polymerization of archaeal RadA protein into long and fine helical filaments.
The Archaeal protein RadA, a RecA/Rad51 homolog, is able to promote pairing and exchange of DNA strands with homologous sequences. Here, we have expressed, purified, and crystallized the catalytically active RadA protein from Sulfolobus solfataricus (Sso). Preliminary X-ray analysis indicated that Sso RadA protein likely forms helical filament in protein crystals. Using atomic force microscopy with a carbon nanotube (CNT) tip for high-resolution imaging, we demonstrated that Sso RadA protein indeed forms fine helical filaments up to 1 microm in length ( approximately 10nm pitch) in the absence of DNA and nucleotide cofactor. We also observed that Sso RadA protein helical filament could dissemble upon incubation with ssDNA, and then the proteins associate with ssDNA to form nucleoprotein filament.
Lee
Ming-Hui
MH
Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan, ROC.
Leng
Chih-Hsiang
CH
Chang
Yuan-Chih
YC
Chou
Chia-Cheng
CC
Chen
Yi-Kai
YK
Hsu
Fu-Fei
FF
Chang
Chia-Seng
CS
Wang
Andrew H-J
AH
Wang
Ting-Fang
TF
D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D003460:Crystallization / Q000379:methods*; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000648:ultrastructure*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D019281:Dimerization; D008969:Molecular Sequence Data; D011108:Polymers / Q000138:chemical synthesis; D011485:Protein Binding; D011487:Protein Conformation; D016944:Sulfolobus / Q000201:enzymology*
D019843:Archaeal Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D011108:Polymers; C117252:RadA protein, archaeal