title: Serine phosphorylation of the cotton cytosolic pyruvate kinase GhPK6 decreases its stability and activity.
abstract: Pyruvate kinase (PK, EC 2.7.1.40) is an important glycolytic enzyme involved in multiple physiological and developmental processes. In this study, we demonstrated that cotton cytosolic pyruvate kinase 6 (GhPK6) was phosphorylated at serines 215 and 402. Phosphorylation of GhPK6 at serine 215 inhibited its enzyme activity, whereas phosphorylation at both serine sites could promote its degradation. The phosphorylation-mediated ubiquitination of GhPK6 was gradually attenuated during the cotton fiber elongation process, which sufficiently explained the increase in the protein/mRNA ratios. These results collectively provided experimental evidence that cotton fiber elongation might be regulated at the post-translational level.
authors.affiliation: Laboratory of Plant Molecular Biology Center for Plant Biology School of Life Sciences Tsinghua University Beijing China; Tsinghua-Peking Center for Life Science Tsinghua University Beijing China.
authors.forename: Bing
authors.identifier: 0000-0001-9774-517X
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Laboratory of Plant Molecular Biology Center for Plant Biology School of Life Sciences Tsinghua University Beijing China.
authors.forename: Jin-Yuan
authors.initials: JY
authors.lastname: Liu
keywords: cotton fiber; fast cell growth; phosphorylation; pyruvate kinase; ubiquitination