XPD Helicase (3CRV): Difference between revisions

== Structure ==

XPD helicase's catalytic core (<scene name='72/728075/Domains/3'>Figure 1</scene>) is composed of four domains, HD1 (green), HD2 (red), 4FeS (brown), and Arch (blue) domains, and six motifs<ref name="Lifuss">PMID: 18510924 </ref>. The HD1 and HD2 domains form the ATP-Binding Interface.The 4FeS domain contains Cysteines 88, 102, 105, and 137 in which the Sulfur-Iron binding occurs (pink), the complex has the role of detecting DNA damage<ref name="Lifuss">PMID: 18510924 </ref>. ssDNA binding is facilitated by the 4FeS domain's Fe-S region and a channel is formed with HD1 and Arch Domains to form a passage way for the ssDNA <ref name="Lifuss">PMID: 18510924 </ref>. Positively charged residues along the channel are paired with negatively charged residues to allow subsequent ssDNA binding and movement along the ssDNA. HD2 domain and the Arch domain form the HD2 gateway which is associated with sensing bulky DNA damage as well<ref name="Lifuss">PMID: 18510924 </ref>. The motif's (<scene name='72/728075/Motifs/3'>Figure 2</scene>), I (31-60, red), II (177-186, blue), III (317-327, green), IV (394-408, brown), V (439-455, purple) and VI (501-517, orange), all play a role in both ATP and DNA binding<ref name="Lifuss">PMID: 18510924 </ref>. Motif's I, II, V, and VI all form the ATP binding site at the HD1 and HD2 interface (<scene name='72/728075/Atp_binding/2'>Figure 3</scene>)<ref name="Lifuss">PMID: 18510924 </ref>. Motif's IV, V, and VI within the HD2 domain form the gateway channel for DNA binding (<scene name='72/728075/Hd2_gate/2'>Figure 4</scene>)<ref name="Lifuss">PMID: 18510924 </ref>.

== Function ==