Tyrosine sulfation is a posttranslational modification common in peptides and proteins synthesized by the secretory pathway in most eukaryotes. In animals, tyrosine sulfation is catalyzed by an enzyme called tyrosylprotein sulfotransferase (TPST), whose activity plays important roles in many physiological and pathological processes including hormonal regulation, hemostasis, inflammation and infectious diseases. Recent identification of the Arabidopsis TPST and a group of tyrosine-sulfated peptides known as root meristem growth factors (RGFs) highlights that, as with in animals, protein tyrosine sulfation also plays important roles in regulating plant growth and development.

Prof. LI chuanyou and his team in the Institute of Genetics and Developmental Biology(IGDB), Chinese Academy of Science (CAS) made important progress in the action mechanism of tpst in maintenance of the root stem cell niche, which in the Arabidopsis root meristem is an area of four mitotically inactive quiescent cells plus the surrounding mitotically active stem cells. Mutation of tpst leads to defective maintenance of the root stem cell niche, decreased meristematic activity and stunted root growth. This work demonstrates that TPST expression is positively regulated by auxin and that mutation of this gene affects auxin distribution by reducing local expression levels of several PIN genes and auxin biosynthetic genes in the stem cell niche region. On the other hand, mutation of TPST impairs basal- and auxin-induced expression of the PLETHORA (PLT) stem cell transcription factor genesand that overexpression of PLT2 rescues the root meristem defects of theloss-of-function mutant of TPST. Together, these results support that TPST acts to maintain root stem cell niche by regulating basal- and auxin-induced expression of PLT1 and 2. TPST-dependent sulfation of RGFs provides a missing link between auxin and PLTs in regulating root stem cell niche maintenance.

Entitled with “Arabidopsis Tyrosylprotein Sulfotransferase Acts in the Auxin/PLETHORA Pathway in Regulating Postembryonic Maintenance of the Root Stem Cell Niche[W],[OA]”, the publication has been published in Plant Cell as a cover story (DOI:10.1105/tpc.110.075721)

http://www.plantcell.org/cgi/content/abstract/tpc.110.075721v1