C-terminal region of protein kinase CK2α: How the structure can affect function and stability of the catalytic subunit
✍ Scribed by Elena Grasselli; Valeria Tomati; Marco V. Bernasconi; Claudio Nicolini; Laura Vergani
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 345 KB
- Volume
- 92
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Abstract
A novel mutant of the catalytic α subunit of human protein kinase CK2 (CK2α) was designed in an attempt to clarify the role of the carboxylic‐terminal segment characteristic of vertebrates, excluding fish. Starting from the sequence alignments, we constructed a phylogenetic tree of the primary structure of CK2α. On this basis, we substituted two distal prolines with alanines (PA 382‐384). Theoretical calculations and spectropolarimetry measurements, performed both on native and mutant subunits, indicate an increased content of α‐helix after this double amino acidic substitution. In order to clarify the structure/function relationship of the C‐terminal region, we verified if the structural change affects the catalytic activity of CK2α. The mutant exhibits slightly increased phosphorylation efficiency, but reduced ability to transfer phosphate in comparison with the native subunit. At last, we compared the thermal stability of the mutant with respect to the native subunit and we tested the proteolytic degradability. The observation that the PA 382‐384 mutant exhibits an increased thermal and proteolytic stability suggests that this mutant could be employed to solve the three‐dimensional (3D) structure of human CK2α and to overcome difficulties in crystallizing the native form. © 2004 Wiley‐Liss, Inc.