Crystal structure of a PR-10 nodulin in complex with trans-zeatin

Nodules are unique root organs of legume plants. Nodulation (nodule formation) is an extraordinary symbiotic

process which eventually allows a plant to assimilate atmospheric nitrogen. The nitrogen-fixing bacteria that colonize

the nodules convert molecular nitrogen N2 into compounds suitable for plant metabolism. A class of plant

hormones called cytokinins are known to affect the nodulation process. A small protein, Nodulin 13 from Medicago

truncatula (MtN13), is expressed in the outer cortex of the nodule at early stages of nodulation. MtN13 belongs

to class 10 of plant pathogenesis-related proteins (PR-10). PR-10 members have been shown to bind cytokinins.

This paper focuses on the involvement of cytokinins in nodulation and presents a brief overview of the

crystal structure of MtN13 in complex with trans-zeatin, a naturally occurring cytokinin.