In the latest issue of Science (19 October 2001), Dr. Klemens Wild and Prof. Dr. Irmgard Sinning of the Biochemistry Centre (BZH) of the University of Heidelberg and Dr. Stephen Cusack, head of the Grenoble outstation of the European Molecular Biology Laboratory (EMBL) report on the high-resolution crystal structure of an early protein-RNA assembly complex of the human signal recognition particle (SRP).
Communication between cells and their environment is one of the fundamental principles involved in any form of life. An important process involved the targeting of protein in and through cell membranes. For transport these proteins contain an amino-terminal signal sequence determining their destination very much like a postal code. The cellular postman involved in all domains of life is the signal recognition particle (SRP). In mammals this is a cytosolic complex consisting of an RNA (SRP RNA) and six proteins.
Important for the understanding of protein targeting is knowledge of the atomic structure of SRP. This can be obtained via X-ray structure analysis. The authors describe the structure of an important protein-RNA complex responsible for the internal organisation of the human SRP. The high resolution 0.18 nm of the structure (SRP19 with 29 nucleotides of SRP RNA helix 6) permits atomic statements on the assembly of the constituent parts and of the protein-RNA interactions.
Newly identified are the specific RNA stem-loop structure and the importance of highly ordered water molecules as molecular "putty" in protein-RNA complexes. Together with other crystal structures already identified, these new data make it possible to propose a partial model of SRP and achieve better understanding of the complex organisation of the particle. The authors are confident that in a project funded by the European "framework V" programme it will soon be possible to replace this model of the cellular postman SRP with a more complex crystal structure with additional SRP components.
Please address any inquiries to:
Prof. Dr. Irmgard Sinning
University oif Heidelberg
Biochemistry Centre (BZH)
phone: 06221/544781, fax: 544790
More general inquiries from journalists can also be addressed to
Dr. Michael Schwarz
Press Officer of the University of Heidelberg
phone: 06221/542310, fax: 54317