“…The oxidative system involving CDHs and copper-dependent LPMOs is crucial for effective degradation of recalcitrant polysaccharides like cellulose, , hemicellulose, starch, and chitin . Compared to using the chemical compounds (e.g., ascorbate) as electron donors, it was considered that employing an enzyme as an electron donor is advantageous because this enables a kinetically controlled supply of electrons to the LPMO. ,,, Despite the fact that the role and significance of LPMOs in the CDH-LPMO system are well recognized and much progress has been achieved in discovering and engineering LPMOs for their industrial application in commercial cellulase cocktail, − there is still less understanding about the CDH-driven reduction mechanism due to the modular structure of CDHs and the long-range electron-transfer process involving IDET and IPET in driving the LPMO reaction. , The IDET between DH and CYT domains in CDH is a particular important process controlling the overall electron-transfer rate; however, the intrinsic determinants in CDH such as the specific sequence and structural element governing the IDET remain elusive, which partially impedes our effort in engineering CDH and ameliorating the CDH-LPMO system efficiency. Here, we demonstrated that an extra lysine-rich sequence in the vicinity of heme b on the CYT domain of Af CDH played a vital role in IDET and activation of AA9 LPMOs.…”