Role of the Kaposi's sarcoma-associated herpesvirus K15 SH3 binding site in inflammatory signaling and B-cell activation.
The Kaposi's sarcoma-associated herpesvirus (KSHV) contains several open reading frames (ORFs) that encode proteins capable of initiating and modulating cellular signaling pathways. Among them is ORF K15, encoding a 12-transmembrane-spanning protein with a cytoplasmic C-terminal domain. Through conserved binding motifs, such as Src homology 2 (SH2) and SH3 binding sites, K15 interacts with cellular proteins, activates the NF-kappaB, MEK/Erk, and Jun N-terminal protein kinase (JNK) pathways, and induces the expression of several inflammatory and angiogenic genes. In this study, we investigated the role of an SH3 domain binding site centered on a PPLP motif in K15. We screened libraries of cellular SH3 domains to identify signaling molecules interacting with the KSHV PPLP motif. We found its affinities for two Src kinase family members, Lyn and Hck, to exceed those of other viral proteins. While the SH2 binding motif YEEV is essential for the inflammatory response induced by KSHV K15, recruitment of Lyn and Hck to the K15 PPLP motif seems to be dispensable for this inflammatory response. However, the PPLP motif is essential for the decrease in B-cell receptor-mediated signaling induced by K15, as measured by calcium mobilization assays.
Institute of Virology, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625 Hanover, Germany.
Marcel
M
Pietrek
Melanie M
MM
Brinkmann
Ilona
I
Glowacka
Anette
A
Enlund
Anika
A
Hävemeier
Oliver
O
Dittrich-Breiholz
Michael
M
Kracht
Marc
M
Lewitzky
Kalle
K
Saksela
Stephan M
SM
Feller
Thomas F
TF
Schulz
D001402:B-Lymphocytes / Q000276:immunology*; D006367:HeLa Cells; D019288:Herpesvirus 8, Human / Q000276:immunology* / Q000502:physiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D008213:Lymphocyte Activation; D011485:Protein Binding; D025941:Protein Interaction Mapping; D051572:Proto-Oncogene Proteins c-hck / Q000378:metabolism; D015398:Signal Transduction; D014764:Viral Proteins / Q000276:immunology* / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
D014764:Viral Proteins; C496631:HCK protein, human; D051572:Proto-Oncogene Proteins c-hck; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases