In vivo phosphorylation and in vitro autophosphorylation-inactivation of Kluyveromyces lactis hexokinase KlHxk1

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Item Type:	Article
Title:	In vivo phosphorylation and in vitro autophosphorylation-inactivation of Kluyveromyces lactis hexokinase KlHxk1
Creators Name:	Kettner, K., Kuettner, E.B., Otto, A., Lilie, H., Golbik, R.P., Straeter, N. and Kriegel, T.M.
Abstract:	The bifunctional hexokinase KlHxk1 is a key component of glucose-dependent signal transduction in Kluyveromyces lactis. KlHxk1 is phosphorylated in vivo and undergoes ATP-dependent autophosphorylation-inactivation in vitro. This study identifies serine-15 as the site of in vivo phosphorylation and serine-157 as the autophosphorylation-inactivation site. X-ray crystallography of the in vivo phosphorylated enzyme indicates the existence of a ring-shaped symmetrical homodimer carrying two phosphoserine-15 residues. In contrast, small-angle X-ray scattering and equilibrium sedimentation analyses reveal the existence of monomeric phosphoserine-15 KlHxk1 in solution. While phosphorylation at serine-15 and concomitant homodimer dissociation are likely to be involved in glucose signalling, mechanism and putative physiological significance of KlHxk1 inactivation by autophosphorylation at serine-157 remain to be established.
Keywords:	Autophosphorylation, Crystal Structure, Hexokinase, Kluyveromyces Lactis, KlHxk1
Source:	Biochemical and Biophysical Research Communications
ISSN:	0006-291X
Publisher:	Elsevier / Academic Press
Volume:	435
Number:	2
Page Range:	313-318
Date:	31 May 2013
Official Publication:	https://doi.org/10.1016/j.bbrc.2013.03.121
PubMed:	View item in PubMed

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