INVESTIGADORES
STUDDERT Claudia Alicia
congresos y reuniones científicas
Título:
- A key residue for function of CheW, the coupling protein in bacterial chemotaxis
Autor/es:
PEDETTA, A; ASILI, RA; STUDDERT, CA
Lugar:
Puerto Madryn
Reunión:
Congreso; XLVI Reunión Anual de SAIB; 2010
Institución organizadora:
SAIB
Resumen:
The coupling protein CheW is essential to transmit the signals
sensed by chemoreceptors to the histidine kinase CheA. The precise
role of CheW during signaling and its arrangement within the
signaling complex have not been elucidated.
The conserved residue R62 in CheW has been proposed to function
as a light switch by displaying important interactions with both
CheA and chemoreceptors.
Cells expressing the point mutant CheW R62H do not mediate
chemotaxis in soft agar plates. However, this mutant protein is able
to mediate kinase activation in vitro. In order to identify its
functional defect, we performed several in vivo assays aimed to
characterize the ability of the mutant protein to modulate kinase
activity, adapt to stimuli and mediate proper clustering of receptors
at the poles of the cell. We found a slight defect in the clustering
ability of the mutant protein, whereas no defects are apparent in the
other signaling abilities. We also characterized previously isolated
suppressors of R62H in both CheA and chemoreceptors.
In order to define the structural arrangement of CheW within the
signaling complex, we introduced cysteine residues in the surface
of both CheW and receptors and assessed their ability to form
disulfides in vivo. We found a specific pair of cysteine replacements
that get crosslinked.
Our results support the relevance of residue R62 in chemotaxis
signaling.