Structure determination of the O-methyltransferase NovP using the 'free lunch algorithm' as implemented in SHELXE

• Published in: Acta Crystallographica Section D Biological Crystallography
• Main Authors: Usón, Isabel, Stevenson, Clare E. M., Lawson, David M., Sheldrick, George M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Blackwell Publishing 2007
• Subjects: Antibiotic biosynthesis; Free lunch algorithm; SHELXE; NovP; O-methyltransferase; Chain tracing; DML
• Online Access: http://hdl.handle.net/10261/113906; https://doi.org/10.1107/S0907444907042230

NovP is an S-adenosyl-l-methionine-dependent O-methyltransferase from Streptomyces spheroides (subunit MW = 29 967 Da). Recombinant N-terminally His-tagged NovP crystallizes in space group P2, with approximate unit-cell parameters a = 51.81, b = 46.04, c = 61.22 Å, β = 105.0°, giving a solvent content of 44% for a single copy of the His-tagged protomer per asymmetric unit. Native synchrotron data to a resolution of 1.35 Å were combined with three other native data sets collected at lower resolution (both in-house and at the synchrotron) for the sake of completeness and better scaling. Data to 2.45 Å resolution were subsequently recorded in-house from a single mercury derivative. Three partial mercury sites could be located with SHELXD, but the resulting phases had a mean error of about 81° and in our hands did not yield an interpretable map using standard automated software. Nevertheless, the structure of NovP could be solved by first tracing a small part of the structure by hand and then extrapolating within and beyond the experimental resolution limit using the 'free lunch algorithm' in SHELXE. The resulting phases have a mean phase error of 17° relative to a refined model. © International Union of Crystallography 2007. IU and GMS are grateful to the European Union Integrated Project BIOXHIT for support. IU thanks the Spanish MEC for financial support (grant BIO2003-06653). CEMS and DML would like to acknowledge the BBSRC for financial support through responsive mode funding (ref. B19400) and the Core Strategic Grant to the John Innes Centre. GMS thanks the Fonds der Chemischen Industrie for support Peer Reviewed