## 4 Conclusions  
Inspired by the cellulosome, a natural multienzyme complex, research on the artificial assembly of multiple GHs has been conducted. Because GHs typically contain one catalytic domain and one or more CBMs, the contribution of clustering multiple catalytic domains and multiple CBMs to the enhancement in the hydrolysis by artificial cellulosomes has not been distinguished. We assembled catalytic moieties derived from two major GHs involved in cellulose degradation, EG and CBH, and demonstrated that synergistic hydrolysis by the two catalytic moieties was not observed. It is likely that the catalytic moieties in the complexes act as weak pseudo-CBMs for each other. Utilizing the heterotrimic PCNA as an interlink, we found that the reversible incorporation of CBM into the catalytic moieties enhanced the cellulose hydrolysis more effectively than irreversible incorporation. This suggests that excessive binding to the substrate limits the benefit of the improved substrate presentation to the catalytic domain, and thus the binding would need to be optimized. Our approach of reversibly assembling a catalytic domain and a substrate-binding module to improve accessibility to a polymeric substrate may also be beneficial for enzymatic reactions with polymeric substrates other than cellulose. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app15042214/s1](https://www.mdpi.com/article/10.3390/app15042214/s1)]([https://www.mdpi.com/article/10.3390/app15042214/s1](https://www.mdpi.com/article/10.3390/app15042214/s1)), Table S1. Primer list for recombinant gene cloning into expression vector pET15b; Figure S1: 3,5-Dinitrosalicylic acid assay to measure total amounts of reducing sugars; Figure S2: Full scan of the original uncropped gel images related to Figure 2; Supporting Methods: construction of expression vector. Conceptualization, K.K.I.S. and H.H. ; methodology, K.K.I.S. and H.H. ; formal analysis, K.K.I.S. ; investigation, K.K.I.S. ; writing--original draft preparation, K.K.I.S. ; writing--review and editing, H.H. ; visualization, K.K.I.S. and H.H. ; supervision, H.H. ; funding acquisition, H.H. All authors have read and agreed to the published version of the manuscript. This research was funded by \"Innovation inspired by Nature\" Research Support Program, Sekisui Chemical CO., LTD. The funder had the following involvement with the study: supporting program. * [PERSON] et al. (2019) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]. Catalytic Conversion of Cellulose to Sorbitol over Ru Supported on Biomass-Derived Carbon-Based Materials. _Appl. Catal. B Environ._**2019**, _256_, 117826. [CrossRef]
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