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

Item Type:Article
Title:In vivo phosphorylation and in vitro autophosphorylation-inactivation of Kluyveromyces lactis hexokinase KlHxk1
Creators Name:Kettner, K. and Kuettner, E.B. and Otto, A. and Lilie, H. and Golbik, R.P. and 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:Academic Press / Elsevier (U.S.A.)
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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