2ZE6

Crystal Structure of adenosine phosphate-isopentenyltransferase complexed with substrate analog, DMASPP

Summary for 2ZE6

• Entry DOI: 10.2210/pdb2ze6/pdb
• Related: 2zE5 2zE7 2zE8
• Descriptor: Isopentenyl transferase, DIMETHYLALLYL S-THIOLODIPHOSPHATE, ADENOSINE MONOPHOSPHATE, ... (4 entities in total)
• Functional Keywords: transferase, crown gall tumor, cytokinin biosynthesis
• Biological source: Agrobacterium tumefaciens
• Total number of polymer chains: 1
• Total formula weight: 29452.19

Authors

Sakakibara, H. (deposition date: 2007-12-06, release date: 2008-02-05, Last modification date: 2024-03-13)

Primary citation

Sugawara, H.,Ueda, N.,Kojima, M.,Makita, N.,Yamaya, T.,Sakakibara, H.
Structural insight into the reaction mechanism and evolution of cytokinin biosynthesis.
Proc.Natl.Acad.Sci.Usa, 105:2734-2739, 2008

PubMed Abstract: The 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.

PubMed: 18258747
DOI: 10.1073/pnas.0707374105

Experimental method

X-RAY DIFFRACTION (2.1 Å)