Figure 6.

Schematic description of the regulation of the main secreted S8 family serine proteases by GATA transcription factors in P. lilacinum. Under a low C:N ratio, the alkaline serine protease Alp1 was regulated by GATA transcription factors SREP, AreA, and NsdD. Under a high C:N ratio, the proteinase T-like protein P32 and serine endopeptidases PR1D were regulated by GATA transcription factors Asd-4, A0A179G170, and A0A179HGL4. The electrostatic potential distribution on the surface of Alp1, P32, and PR1D is shown, with the electrostatic potential colored from red (negative) to blue (positive). The binding sites on the peptide substrate interacting with the protease-binding pockets S4–S4’ were labeled as P4, P3, P2, P1, P1’, P2’, P3’, and P4’, from N-terminal (N) to C-terminal (C). Substrate cleavage occurred between P1 and P1’.