Crystallization and preliminary X-ray analysis of maltose O-acetyltransferase

• Published in: Acta crystallographica. Section D, Biological crystallography. Biological crystallography., 2001-12, Vol.57 (12), p.1915-1918
• Main Authors: Lo Leggio, Leila, Dal Degan, Florence, Poulsen, Peter, Sørensen, Susanne Oxenbøll, Harlow, Kenneth, Harris, Pernille, Larsen, Sine
• Format: Article
• Language: English
• Subjects: Acetyltransferases - chemistry; buffer pH; Cloning, Molecular; crystal polymorphism; Crystallization; Crystallography, X-Ray; Escherichia coli - enzymology; hexapeptide-repeat enzymes; left-handed parallel β-helix; maltose O-acetyltransferase; native Patterson; Polymers - chemistry; Protein Conformation
• ISSN: 1399-0047; 0907-4449; 1399-0047
• DOI: 10.1107/S0907444901016298

Maltose O‐acetyltransferase (Mac) is a member of the hexapeptide‐repeat family of enzymes, which contains proteins with left‐handed parallel β‐helix architecture forming homotrimers. Diffraction data for four well diffracting crystal forms were collected. Crystal form I diffracted beyond 1.53 Å resolution but was perfectly merohedrally twinned with an apparent space group P622. Crystal forms II and III (space groups R3 and C2, respectively) could be obtained under very similar conditions by adjusting the buffer pH differently. Crystal forms II and III had several monomers in the asymmetric unit and were difficult to derivatize. However, during soaking with trimethyl lead acetate, the form III crystals dissolved and crystals with a different habit and space group grew in their place (form IV). In three of the crystal forms, a ladder of peaks was visible in the native Patterson maps along the c axis. These peaks were interpreted as corresponding to the vectors between the β‐strands in the turns of the β‐helix. Crystal form IV is suitable for structure determination of Mac exploiting the anomalous scattering of lead.