Specifically blocks the catalytic activity of the chorismate mutase Cmu1 from the fungal pathogen Ustilago maydis. Hinders substrate access to the active site of Cmu1 through intimate interactions (PubMed:30651637). A structural feature specific to the fungal secreted Cmu1 called extensive loop region (ELR) is required for the intimate interaction (PubMed:30651637). Does not interact with its own chorismate mutases (PubMed:30651637). The secreted fungal Cmu1 presumably affects biosynthesis of the plant immune signal salicylic acid by channelling chorismate into the phenylpropanoid pathway (PubMed:30651637). Monomer (PubMed:30651637). Interacts with Cmu1 of the fungal pathogen Ustilago maydis (PubMed:30651637). A structural feature specific to the fungal secreted Cmu1 called extensive loop region (ELR) is required for the intimate interaction (PubMed:30651637). Does not interact with its own chorismate mutases (PubMed:30651637). Induced by the fungal pathogen Ustilago maydis. Belongs to the kiwellin family.