摘要：Many annotated fungal genomes harbour high proportions of hypothetical proteins with or without domains of unknown function (DUF). Here, three novel proteins (342−497 amino acids), each containing only a single large DUF1996 (231−250 residues) region with highly conserved head (DPIXXP) and tail (HXDXXXGW) signatures, were expressed as eGFP-tagged fusion proteins and shown to specifically localize in the vacuoles of Beauveria bassiana , a filamentous fungal entomopathogen; therefore, these proteins were named vacuole-localized proteins (VLPs). The VLPs have one to three homologues in other entomopathogenic or non-entomopathogenic filamentous fungi but no homologues in yeasts. The large DUF1996 regions can be formulated as D-X4-P-X5–6-H-X-H-X3-G-X25–26-D-X-S-X-YW-X-P-X123–203-CP-X39–48-H-X-D-X3-GW; the identical residues likely involve in a proton antiport system for intracellular homeostasis. Single deletions of three VLP-coding genes ( vlp1 – 3 ) increased fungal sensitivities to cell wall perturbation, high osmolarity, oxidation, and several metal ions. Conidial thermotolerance decreased by ~11% in two Δ vlp mutants, and UV-B resistance decreased by 41−57% in three Δ vlp mutants. All the changes were restored by targeted gene complementation. However, the deletions did not influence fungal growth, conidiation, virulence or Cu2+ sensitivity. Our findings unveiled a role for the DUF1996 regions of three B. bassiana VLPs in the regulation of multiple stress responses and environmental adaptation.
