Secreted chorismate mutase that is one component of a cocktail of effectors shaping the host metabolome and acting as virulence factors. The enzyme is taken up by plant cells, can spread to neighboring cells where it affects the biosynthesis of the plant immune signal salicylic acid by channelling chorismate into the phenylpropanoid pathway (PubMed:21976020, PubMed:30651637). Interfers with the activity of host cytosolic chorismate mutase CM2 through heterodimerization (PubMed:21976020). chorismate = prephenate Contrary to classical chorismate mutases, CMU1 is not subject to allosteric regulation by tryptophan and tyrosine (PubMed:21976020, PubMed:30651637). Activity is decreased in a non-competitive and allosteric manner by the binding of the host defense kiwellin KWL1 which probably blocks substrate access to the active site of CMU1 (PubMed:30651637). Homodimer (PubMed:21976020, PubMed:30651637). Forms a heterodimer with the host cytosolic chorismate mutase CM2 (PubMed:21976020). Interacts with the host kiwellin KWL1 which acts as a defense protein that protects maize from infection (PubMed:30651637). Is translocated to host plant cells and spreads to neighboring tissue. The spreading is likely to occur through plasmodesmata. Expression is specifically up-regulated during biotrophic development (PubMed:21976020). CMU1 is one of the most highly expressed fungal genes during plant colonization (PubMed:20360107). The extensive loop region (ELR) is specific for fungal secreted chorismate mutases and is required for the interaction with the host defense kiwellin KWL1. Decreases significantly the amount of tumors produced during host maize infection.