Two bean cell wall proteins more abundant during water deficit are high in proline and interact with a plasma membrane protein.

GARCÍA-GÓMEZ BI, CAMPOS F, HERNÁNDEZ M, BATTAGLIA M, CUÉLLAR S, COVARRUBIAS AA.

San Diego, CA USA

Congreso; ASPB (American Society of Plant Biology) (2000) - San Diego, CA USA; 2000

ASPB (American Society of Plant Biology)

Two antigenically related glycoproteins, called p33 and p36 accumulate in the soluble fraction of the cell wall in response to water deficit in Phaseolus vulgaris (Covarrubias et al., Plant Physiol.107:1119-1128,1995). In this work, we show that p33 and p36 are able to adhere to leaf protoplasts and that they bind to plasma membrane (PM) vesicles, in a divalent cations-dependent manner. Data from the partial amino acid sequence of the p33 and p36 proteins indicate that they contain repeats of the decapeptide POVYKPOVEK; therefore, they are related to proline-rich proteins. Binding assays demonstrate that both proteins specifically bind to an 80 kDa PM protein. This binding is competed with a peptide that contains the RGD motif, as well as with fibronectin, which also includes this sequence, suggesting that the 80 kDa PM protein has an integrin-like function whose natural ligands are p33 and p36. Our data support the idea that PRPs play an important role, either during plant development or in response to environmental stimuli, by the recognition of specific PM proteins and further triggering of particular functions. The fact that p33/p36 accumulate in response to water deficit suggests that these proteins may participate to maintain a tight adhesion of the PM to the cell wall, as well as to trigger cell responses to osmotic stress.