Crystallization and preliminary X-ray crystallographic studies of transglutaminase 2 in complex with Ca²⁺

Abstract

Transglutaminase 2 (TG2) is a multi-functional protein that has been implicated in a variety of physiological cellular activities, including apoptosis, angiogenesis and cellular differentiation. Two functions of TG2 are protein cross-linking and GTP hydrolysis activities. The protein cross-linking activity of TG2 is positively controlled by calcium; however, the molecular mechanism of its Ca 2+ -dependent activity is completely unknown. In the present study, full-length human TG2 in complex with Ca 2+ was overexpressed, purified and crystallized at 20 C as a first step towards elucidating this mechanism. X-ray diffraction data were collected to a resolution of 3.4 Å from a crystal belonging to space group C222 1 , with unitcell parameters a = 133.08, b = 216.30, c = 166.26 Å . Based on these data, the asymmetric unit was estimated to contain three molecules.

Competitive Binding of Magnesium to Calcium Binding Sites Reciprocally Regulates Transamidase and GTP Hydrolysis Activity of Transglutaminase 2

“…To identify the Ca 2+ binding sites, a Ca 2+ -containing crystal of TG2 was produced in totally different crystallization conditions from those used for the previous structural study of TG2 [25]. A relatively low-resolution structure of 3.56 Å was solved and refined to R work = 22.5% and R free = 26.3%.…”

“…The method for TG2 protein expression and purification was introduced in previous structural studies [25]. Briefly, the full-length human TG2 gene encoding G224 was inserted into a home-made pOKD5 vector.…”