Histidine kinase involved in a two-component signaling pathway that regulates cell wall mannan biosynthesis. Required for hyphal formation and virulence. Plays a role in fungicides sensitivity, probably through the positive regulation of the HOG1-signaling pathway. Presumed to mediate phosphotransfer to the HOG1 MAP kinase pathway during oxidative and perhaps osmotic stress. ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Expression is increased in opaque cells. The HAMP domains are critical for the sensitivity to fungicides such as fludioxonil, as well as for activation of HOG1. The phosphorelay mechanism involves the sequential transfer of a phosphate group from His-510 (H1) in the histidine kinase domain (transmitter domain) to Asp-924 (D1) of the response regulatory domain (receiver domain). This transfer probably occurs between two NIK1 molecules, rather than intramolecularly (By similarity). Impairs the hyphal formation and attenuates the virulence in a mouse systemic candidiasis model.