Structural highlights
Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe phytohormone cytokinin regulates plant growth and development. This hormone is also synthesized by some phytopathogenic bacteria, such as Agrobacterium tumefaciens, and is as a key factor in the formation of plant tumors. The rate-limiting step of cytokinin biosynthesis is catalyzed by adenosine phosphate-isopentenyltransferase (IPT). Agrobacterium IPT has a unique substrate specificity that enables it to increase trans-zeatin production by recruiting a metabolic intermediate of the host plant's biosynthetic pathway. Here, we show the crystal structures of Tzs, an IPT from A. tumefaciens, complexed with AMP and a prenyl-donor analogue, dimethylallyl S-thiodiphosphate. The structures reveal that the carbon-nitrogen-based prenylation proceeds by the SN2-reaction mechanism. Site-directed mutagenesis was used to determine the amino acid residues, Asp-173 and His-214, which are responsible for differences in prenyl-donor substrate specificity between plant and bacterial IPTs. IPT and the p loop-containing nucleoside triphosphate hydrolases likely evolved from a common ancestral protein. Despite structural similarities, IPT has evolved a distinct role in which the p loop transfers a prenyl moiety in cytokinin biosynthesis. Structural insight into the reaction mechanism and evolution of cytokinin biosynthesis.,Sugawara H, Ueda N, Kojima M, Makita N, Yamaya T, Sakakibara H Proc Natl Acad Sci U S A. 2008 Feb 19;105(7):2734-9. Epub 2008 Feb 7. PMID:18258747[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. ReferencesContents | ||||||||||||||||||||||||
This page was last modified 05:07, 2 October 2014.