Chitcholtan K, Garrill A. A beta4 integrin-like protein co-localises with a phosphotyrosine containing protein in the oomycete Achlya bisexualis: inhibition of tyrosine phosphorylation slows tip growth.
Fungal Genet Biol 2005;
42:534-45. [PMID:
15893255 DOI:
10.1016/j.fgb.2005.03.010]
[Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 03/10/2005] [Accepted: 03/16/2005] [Indexed: 11/21/2022]
Abstract
We present immunocytochemical data that indicate the presence of, and a close association between beta4 integrin-like proteins and proteins containing phosphorylated tyrosine residues in the oomycete Achlya bisexualis. When hyphae were plasmolysed, these proteins were present in wall-membrane attachment sites where there was also F-actin. A combination of immunoblots, ELISA, and a coupled enzyme assay suggest that phosphorylation may occur by both autophosphorylation and through the action of a tyrosine kinase. Tyrphostins, which are inhibitors of tyrosine kinases, abolished the anti-phosphotyrosine staining, inhibited the kinase activity, slowed tip growth and affected the organisation of the actin cytoskeleton, in a dose-dependent manner. By analogy with the integrins and associated kinases of the metazoa we suggest that these proteins could contribute to the process of tip growth by providing a means of bidirectional signaling between the cell wall and the cytoplasm.
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