The proteasome regulates gene expression in eukaryotes by rapidly eliminating unnecessary proteins. F-box proteins play a fundamental role in this process by binding proteins that are directed towards the “trash processor” SCF complex, where they are ubiquitinated for final degradation in the proteasome. F-box proteins do not act indiscriminately, but recruit specific targets thus regulating their cellular levels.
In fungi, F-box proteins have been associated with cell cycle control, glucose regulation or circadian rythm and, more recently, with plant infection. In Fusarium, two F-box proteins of the SCF complex are implicated in pathogenicity, Frp1 in F. oxysporum and Fbp1 in F. graminearum. In F. oxysporum we identified a gene orthologue of fbp1 from F. graminearum. We have shown that Fbp1 is implicated in virulence of F. oxysporum f.sp. lycopersici, since the gene knockout mutants display a significant delay in tomato plant infection. Our study indicates a link between MAPK Fmk1 cascade signalling and the Fbp1 protein. Our effort is directed now to know the Fbp1 target proteins involved in the Fmk1 cascade.
Proteomic analysis revealed the presence of up to 80 proteins that are differentially expressed during growth on minimal medium, under conditions in which the mutant strain is limited in invasive growth.
A 14-3-3 protein, Bmh2, has been identified as one of the more expressed proteins in the Dfbp1 mutant in relation to the wild type, suggesting that Bmh2 is a target of Fbp1 to be recruited and degraded by proteasome. Our current research addresses to understand the role of Bmh2 in the pathogenicity of F. oxysporum  and their regulation by Fbp1.