INVESTIGADORES
STUDDERT Claudia Alicia
congresos y reuniones científicas
Título:
COILED COIL CHEMORECEPTORS: IMPORTANCE OF SYMMETRIC INTERACTIONS BETWEEN HELICES FOR FUNCTION
Autor/es:
MASSAZZA, DA; IZZO, SA; STUDDERT, CA
Lugar:
Puerto Madryn
Reunión:
Congreso; XLVI Reunión Anual de SAIB; 2010
Institución organizadora:
SAIB
Resumen:
Bacterial transmembrane chemoreceptors (MCPs for methylaccepting
chemotaxis protein) transmit extracellular signals to an
associated kinase in order to govern the chemotactic behavior of
the cell. The highly conserved cytoplasmic domain of MCPs
consists in a long alpha-helical hairpin that forms, in the dimer, a
four-helix coiled coil bundle. A comparison between MCP
sequences from many microorganisms allowed their classification
into families based in the presence of symmetric
insertions/deletions of seven aminoacids in their cytoplasmic
domains.In order to test the importance of proper interaction
between the two antiparallel helices within the monomer, we
introduced a heptad deletion in the N-helix, the C-helix or both, in
symmetric arrangement, of the serine-sensing MCP of E. coli, Tsr.
We then tested the effect of these deletions on function and in vivo
organization.We observed that the asymmetric constructions lost
their function, while the symmetric one retained parcial function
and maintained the organization of wild type Tsr. Moreover, point
mutations in this latter construction restored full chemotactic
abilities. These results suggest the need to preserve symmetric
interactions between the antiparallel helices in the monomer,
consistent with the observed evolutionary pattern of MCPs. Such
interactions might also be relevant in other coiled coil signaling
proteins.