Download MendeleyCrystal Structure of the Interleukin-15{middle dot}Interleukin-15 Receptor {alpha} Complex: INSIGHTS INTO TRANS AND CIS PRESENTATION
Olsen, S.K., Ota, N., Kishishita, S., Kukimoto-Niino, M., Murayama, K., Uchiyama, H., Toyama, M., Terada, T., Shirouzu, M., Kanagawa, O., Yokoyama, S.(2007) J Biol Chem 282: 37191-37204
- PubMed: 17947230
- DOI: https://doi.org/10.1074/jbc.M706150200
- Primary Citation of Related Structures:
2PSM - PubMed Abstract:
Interleukin (IL)-15 is a pleiotropic cytokine that plays a pivotal role in both innate and adaptive immunity. IL-15 is unique among cytokines due to its participation in a trans signaling mechanism in which IL-15 receptor alpha (IL-15Ralpha) from one subset of cells presents IL-15 to neighboring IL-2Rbeta/gammac-expressing cells. Here we present the crystal structure of IL-15 in complex with the sushi domain of IL-15Ralpha. The structure reveals that the alpha receptor-binding epitope of IL-15 adopts a unique conformation, which, together with amino acid substitutions, permits specific interactions with IL-15Ralpha that account for the exceptionally high affinity of the IL-15.IL-15Ralpha complex. Interestingly, analysis of the topology of IL-15 and IL-15Ralpha at the IL-15.IL-15Ralpha interface suggests that IL-15 should be capable of participating in a cis signaling mechanism similar to that of the related cytokine IL-2. Indeed, we present biochemical data demonstrating that IL-15 is capable of efficiently signaling in cis through IL-15Ralpha and IL-2Rbeta/gammac expressed on the surface of a single cell. Based on our data we propose that cis presentation of IL-15 may be important in certain biological contexts and that flexibility of IL-15Ralpha permits IL-15 and its three receptor components to be assembled identically at the ligand-receptor interface whether IL-15 is presented in cis or trans. Finally, we have gained insights into IL-15.IL-15Ralpha.IL-2Rbeta.gammac quaternary complex assembly through the use of molecular modeling.
Organizational Affiliation:
RIKEN Genomic Sciences Center, RIKEN Yokohama Institute, Kanagawa, Japan.
