(1Z63, 1Z6A, 1Z5Z)
The structure of the archaeal Sulfolobus solfataricus Snf2 family member SSO1653 structure 1 is for a 475 residue fragment of the spanning from residue 431 to the C terminus of the native protein. This represents almost exactly the common Snf2 family region.
The polypeptide fragment was crystallised both in the absence (pdb code 1Z6A) and presence of DNA (pdb code 1Z63, fig 1). A third structure encompasses only the C terminal domain at higher resolution (pdb code 1Z5Z).
The fold of each core recA-like domain is substantially similar and related to those of other known SF2 helicases. However, in both the structures with and without DNA the recA-like domain 2 is flipped by some 180º to an arrangement never previously observed for a helicase (fig 2). This unusual orientation in SSO1653 is observed for both the DNA free and DNA-bound forms 1.
The structure publication refers to the protein as SsoRad54cd because previous definitions identified Rad54 as the highest homology. the bioinformatic analysis at this site places the protein in an independent SSO1653 subfamily for which it is the achetypal member.
In the Sulfolobus solfataricus P2 strain complete genome, the sequence of this protein is comprised of 2 polypeptides SSO1653 and SSO1655 interrupted by a 48kD transposase SSO1654 inserted between motif IV and V. It is unlikely that the enzyme is active with this insertion, and the transposase appears to be mobile (M White, personal communication). We refer to the fusion of SSO1653 and SSO1655 without transposase as SSO1653.
There is no obvious homologue to S solfataricus SSO1653 in the other two Sulfolobus complete genomes.
| description | 'SsoRad54cd' |
| resolution | 3.0A |
| organism | Sulfolobus solfataricus |
| residues | 431-906 (end) |
| DNA | no |
| ADP/ATP | no |
| description | 'SsoRad54cd:dsDNA' |
| resolution | 3.0A |
| organism | Sulfolobus solfataricus |
| residues | 431-906 (end) |
| DNA | 19 base pairs |
| ADP/ATP | no |
| description | 'Domain 2' |
| resolution | 2.0A |
| organism | Sulfolobus solfataricus |
| residues | 630-906 (end) |
| DNA | no |
| ADP/ATP | no |
| PDB | 1Z6A, 1Z63, 1Z5Z |
| PDBsum | 1z6a, 1z63, 1z5z |
| PubMed | 15882619 |
| S solfataricus genome | SSO1653, SSO1655 |
| NCBI RefSeq | NP_343076, NP_343078 |
| SwissProt | Q97XQ7, Q97XQ5 |
| Jmol viewer | 1z6a, 1z63, 1z5z |
| motif I | 466-480 |
| motif Ia | 499-504 |
| motif II | 560-567 |
| motif III | 589-594 |
| motif IV | 749-759 |
| motif V | 806-823 |
| motif VI | 838-845 |
| N terminal | 431-462 |
| domain 1A | 463-631 |
| domain 1B | 632-660 |
| domain 2Aa | 661-670 |
| domain 2Ba | 671-724 |
| domain 2A | 725-858 |
| domain 2Bb | 859-906 |
| Ib | 524-528 |
| Ic | 538-545 |
| IIa (switch) | 567-574 |
| Hinge | 653-660 |
| IVa | 780-787 |
| Va | 829-831 |