Open AccessCrystallization and calcium/sulfur SAD phasing of the human EF‐hand protein S100A2
Author(s) -
Koch Michael,
Diez Joachim,
Wagner Armin,
Fritz Günter
Publication year - 2010
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309110030691
Subject(s) - crystallization , sulfur , calcium , materials science , crystallography , chemistry , metallurgy , organic chemistry
Human S100A2 is an EF‐hand protein and acts as a major tumour suppressor, binding and activating p53 in a Ca 2+ ‐dependent manner. Ca 2+ ‐bound S100A2 was crystallized and its structure was determined based on the anomalous scattering provided by six S atoms from methionine residues and four calcium ions present in the asymmetric unit. Although the diffraction data were recorded at a wavelength of 0.90 Å, which is usually not assumed to be suitable for calcium/sulfur SAD, the anomalous signal was satisfactory. A nine‐atom substructure was determined at 1.8 Å resolution using SHELXD , and SHELXE was used for density modification and phase extension to 1.3 Å resolution. The electron‐density map obtained was well interpretable and could be used for automated model building by ARP / wARP .