GNNGL-PPI: multi-category prediction of protein-protein interactions using graph neural networks based on global graphs and local subgraphs.

Most proteins exert their functions by interacting with other proteins, making the identification of protein-protein interactions (PPI) crucial for understanding biological activities, pathological mechanisms, and clinical therapies. Developing effective and reliable computational methods for predicting PPI can significantly reduce the time-consuming and labor-intensive associated traditional biological experiments. However, accurately identifying the specific categories of protein-protein interactions and improving the prediction accuracy of the computational methods remain dual challenges. To tackle these challenges, we proposed a novel graph neural network method called GNNGL-PPI for multi-category prediction of PPI based on global graphs and local subgraphs. GNNGL-PPI consisted of two main components: using Graph Isomorphism Network (GIN) to extract global graph features from PPI network graph, and employing GIN As Kernel (GIN-AK) to extract local subgraph features from the subgraphs of protein vertices. Additionally, considering the imbalanced distribution of samples in each category within the benchmark datasets, we introduced an Asymmetric Loss (ASL) function to further enhance the predictive performance of the method. Through evaluations on six benchmark test sets formed by three different dataset partitioning algorithms (Random, BFS, DFS), GNNGL-PPI outperformed the state-of-the-art multi-category prediction methods of PPI, as measured by the comprehensive performance evaluation metric F1-measure. Furthermore, interpretability analysis confirmed the effectiveness of GNNGL-PPI as a reliable multi-category prediction method for predicting protein-protein interactions.

A comprehensive review of the recent advances on predicting drug-target affinity based on deep learning.

Accurate calculation of drug-target affinity (DTA) is crucial for various applications in the pharmaceutical industry, including drug screening, design, and repurposing. However, traditional machine learning methods for calculating DTA often lack accuracy, posing a significant challenge in accurately predicting DTA. Fortunately, deep learning has emerged as a promising approach in computational biology, leading to the development of various deep learning-based methods for DTA prediction. To support researchers in developing novel and highly precision methods, we have provided a comprehensive review of recent advances in predicting DTA using deep learning. We firstly conducted a statistical analysis of commonly used public datasets, providing essential information and introducing the used fields of these datasets. We further explored the common representations of sequences and structures of drugs and targets. These analyses served as the foundation for constructing DTA prediction methods based on deep learning. Next, we focused on explaining how deep learning models, such as Convolutional Neural Networks (CNNs), Recurrent Neural Networks (RNNs), Transformer, and Graph Neural Networks (GNNs), were effectively employed in specific DTA prediction methods. We highlighted the unique advantages and applications of these models in the context of DTA prediction. Finally, we conducted a performance analysis of multiple state-of-the-art methods for predicting DTA based on deep learning. The comprehensive review aimed to help researchers understand the shortcomings and advantages of existing methods, and further develop high-precision DTA prediction tool to promote the development of drug discovery.

Drug-Online: an online platform for drug-target interaction, affinity, and binding sites identification using deep learning.

BACKGROUND: Accurately identifying drug-target interaction (DTI), affinity (DTA), and binding sites (DTS) is crucial for drug screening, repositioning, and design, as well as for understanding the functions of target. Although there are a few online platforms based on deep learning for drug-target interaction, affinity, and binding sites identification, there is currently no integrated online platforms for all three aspects. RESULTS: Our solution, the novel integrated online platform Drug-Online, has been developed to facilitate drug screening, target identification, and understanding the functions of target in a progressive manner of "interaction-affinity-binding sites". Drug-Online platform consists of three parts: the first part uses the drug-target interaction identification method MGraphDTA, based on graph neural networks (GNN) and convolutional neural networks (CNN), to identify whether there is a drug-target interaction. If an interaction is identified, the second part employs the drug-target affinity identification method MMDTA, also based on GNN and CNN, to calculate the strength of drug-target interaction, i.e., affinity. Finally, the third part identifies drug-target binding sites, i.e., pockets. The method pt-lm-gnn used in this part is also based on GNN. CONCLUSIONS: Drug-Online is a reliable online platform that integrates drug-target interaction, affinity, and binding sites identification. It is freely available via the Internet at http://39.106.7.26:8000/Drug-Online/ .

Sequence-Structure Analysis Unlocking the Potential Functional Application of the Local 3D Motifs of Plant-Derived Diterpene Synthases.

Plant-derived diterpene synthases (PdiTPSs) play a critical role in the formation of structurally and functionally diverse diterpenoids. However, the specificity or functional-related features of PdiTPSs are not well understood. For a more profound insight, we collected, constructed, and curated 199 functionally characterized PdiTPSs and their corresponding 3D structures. The complex correlations among their sequences, domains, structures, and corresponding products were comprehensively analyzed. Ultimately, our focus narrowed to the geometric arrangement of local structures. We found that local structural alignment can rapidly localize product-specific residues that have been validated by mutagenesis experiments. Based on the 3D motifs derived from the residues around the substrate, we successfully searched diterpene synthases (diTPSs) from the predicted terpene synthases and newly characterized PdiTPSs, suggesting that the identified 3D motifs can serve as distinctive signatures in diTPSs (I and II class). Local structural analysis revealed the PdiTPSs with more conserved amino acid residues show features unique to class I and class II, whereas those with fewer conserved amino acid residues typically exhibit product diversity and specificity. These results provide an attractive method for discovering novel or functionally equivalent enzymes and probing the product specificity in cases where enzyme characterization is limited.

MMDTA: A Multimodal Deep Model for Drug-Target Affinity with a Hybrid Fusion Strategy.

The prediction of the drug-target affinity (DTA) plays an important role in evaluating molecular druggability. Although deep learning-based models for DTA prediction have been extensively attempted, there are rare reports on multimodal models that leverage various fusion strategies to exploit heterogeneous information from multiple different modalities of drugs and targets. In this study, we proposed a multimodal deep model named MMDTA, which integrated the heterogeneous information from various modalities of drugs and targets using a hybrid fusion strategy to enhance DTA prediction. To achieve this, MMDTA first employed convolutional neural networks (CNNs) and graph convolutional networks (GCNs) to extract diverse heterogeneous information from the sequences and structures of drugs and targets. It then utilized a hybrid fusion strategy to combine and complement the extracted heterogeneous information, resulting in the fused modal information for predicting drug-target affinity through the fully connected (FC) layers. Experimental results demonstrated that MMDTA outperformed the competitive state-of-the-art deep learning models on the widely used benchmark data sets, particularly with a significantly improved key evaluation metric, Root Mean Square Error (RMSE). Furthermore, MMDTA exhibited excellent generalization and practical application performance on multiple different data sets. These findings highlighted MMDTA's accuracy and reliability in predicting the drug-target binding affinity. For researchers interested in the source data and code, they are accessible at http://github.com/dldxzx/MMDTA.

Research Progress of Nervonic Acid Biosynthesis.

Nervonic acid (NA) is a very-long-chain monounsaturated fatty acid with great application values. It plays a vital role in the development of brain nervous system and the treatment of neurological diseases, so it has attracted much attention from all walks of life. Although NA has a wide range of sources, its current acquisition methods are still mainly relied on chemical synthesis and plant extraction, which are challenging to meet the market and green industry demands, limiting its development and application. In recent years, with the rapid development of synthetic biology technology, NA biosynthesis has become an alternative production strategy. In this study, we summarize the physicochemical properties, pharmacological activities, resources, biosynthetic pathways and heterologous biosynthesis of NA, and discuss the challenges and prospects of NA biosynthesis. The application prospects of cell-free systems and retrobiosynthesis in NA synthesis were also reviewed.

Characteristics of NtCCD1-3 from tobacco, and protein engineering of the CCD1 to enhance ß -ionone production in yeast.

Biosynthesis of ß-ionone by microbial cell factories has become a promising way to obtain natural ß-ionone. The catalytic activity of carotenoid cleavage dioxygenase 1 (CCD1) in cleavage of ß-carotene to ß-ionone severely limits its biosynthesis. In this study, NtCCD1-3 from Nicotiana tabacum with high ability to cleave ß-carotene was screened. Multiple strategies for improving the ß-ionone yield in Saccharomyces cerevisiae were performed. The results showed that NtCCD1-3 could cleave a variety of caroteniods at the 9,10 (9',10') double bonds and lycopene at the 5,6 (5',6') positions. The insertion site delta for NtCCD1-3 gene was more suitable for enhancing the yield of ß-ionone, showing 19.1-fold increase compared with the rox1 site. More importantly, mutant K38A of NtCCD1-3 in membrane-bonding domains could greatly promote ß-ionone production by more than 3-fold. We also found that overexpression of the NADH kinase Pos5 could improve ß-ionone yield up to 1.5 times. These results may provide valuable references for biosynthesis of ß-ionone.

Characteristics of a new carotenoid cleavage dioxygenase NtCCD10 derived from Nicotiana tabacum.

MAIN CONCLUSION: A new carotenoid cleavage dioxygenase NtCCD10 from tobacco was characterized. There is some difference between NtCCD10 and CCD1 in structure. NtCCD10 can cleave the C5-C6 (C5'-C6') and C9-C10 (C9'-C10') double bonds of carotenoids and has high catalytic activity. Carotenoid cleavage dioxygenases (CCDs) cleave carotenoids to produce a variety of apocarotenoids, which have important biological functions for organisms in nature. There are eleven CCDs subfamilies in the plant kingdom, many of which have been extensively characterized in their functions. However, as a newly classified subfamily, the function of CCD10 has rarely been studied. In this work, the function of an NtCCD10 gene from dicotyledonous Nicotiana tabacum was cloned and characterized, and its phylogeny, molecular structural modeling and protein structure were also systematically analyzed. Like other CCDs, NtCCD10 also possesses a seven bladed ß-propeller with Fe2+ cofactor in its center constituting the active site of the enzyme. The Fe2+ is also coordinated bonding with four conserved histidine residues. Meanwhile, NtCCD10 also has many unique features, such as its α1 and α3 helixes are not anti-parallel, a special ß-sheet and a longer access tunnel for substrates. When expressed in engineered Escherichia coli (producing phytoene, lycopene, ß-carotene, and zeaxanthin) and Saccharomyces cerevisiae (producing ß-carotene), NtCCD10 could symmetrically cleave phytoene and ß-carotene at the C9-C10 and C9'-C10' positions to produce geranylacetone and ß-ionone, respectively. In addition, NtCCD10 could also cleave the C5-C6 and C5'-C6' double bonds of lycopene to generate 6-methyl-5-heptene-2-one (MHO). NtCCD10 has higher catalytic activity than PhCCD1 in yeast, which provides a good candidate CCD for biosynthesis of ß-ionone and has potential applications in biotechnological industry. This study identified the taxonomic position and catalytic activity of the first NtCCD10 in dicotyledonous plants. This will provide a reference for the discovery and functional identification of CCD10 enzymes in dicotyledons.

De Novo Biosynthesis of Oleanane-Type Ginsenosides in Saccharomyces cerevisiae Using Two Types of Glycosyltransferases from Panax ginseng.

Oleanane-type ginsenosides are highly biologically active substances in Panax ginseng, a popular Chinese dietary plant. Lack of key enzymes for glycosylation reactions has hindered de novo synthesis of these bioactive molecules. We mined candidate glycosyltransferases (GTs) of the ginseng database by combining key metabolites and transcriptome coexpression analyses and verified their function using in vitro enzymatic assays. The PgCSyGT1, a cellulose synthase-like GT rather than a UDP-dependent glucuronosyltransferase (UGT), was verified as the key enzyme for transferring a glucuronosyl moiety to the free C3-OH of oleanolic acid to synthesize calenduloside E. Two UGTs (PgUGT18 and PgUGT8) were first identified as, respectively, catalyzing the glycosylation reaction of the second sugar moiety of C3 and the C28 in the oleanane-type ginsenoside biosynthetic pathway. Then, we integrated these GTs in combinations into Saccharomyces cerevisiae genome and realized de novo biosynthesis of oleanane-type ginsenosides with a yield of 1.41 µg/L ginsenoside Ro in shake flasks. This report provides a basis for effective biosynthesis of diverse oleanane-type ginsenosides in microbial cell factories.

Viridibacillus soli sp. nov., isolated from forest soil in Ailaoshan National Nature Reserve.

A Gram stain-positive, rod-shaped, and subterminal endospore-forming bacterium, designated strain YIM B01967T, was isolated from a forest soil sample collected in Ailaoshan National Nature Reserve, Yuxi City, Xinpin county, Yunnan province, China. Strain YIM B01967T showed the highest 16S rRNA gene sequence similarity with Viridibacillus arvi (99.1%) and Viridibacillus arenosi (98.9%). Based on the phylogenetic and 16S rRNA gene sequence results, strain YIM B01967T was affiliated to the genus Viridibacillus. The growth of YIM B01967T was observed at 15-35 °C (optimum, 28 °C), pH 7.0-9.0 (optimum, pH 7.5) and in the presence of 0-2% (w/v) NaCl (optimum in 2% NaCl). The cell wall sugars include ribose, glucose, arabinose, galactose, and mannose. The quinone system consisted of the major compound MK-8 and moderate amounts of MK-7. The major fatty acids (> 10%) included iso-C15:0, anteiso-C15:0, C16:1 ω10c. The major polar lipids profile included DPG, PME. The cell wall peptidoglycan was most likely of the type A4α with an L-Lys-D-Asp interpeptide bridge. The genomic DNA G + C content of strain YIM B01967T was 36.3 mol%. The ANI and digital DNA-DNA hybridization (dDDH) values between strain YIM B01967T and Viridibacillus arvi DSM 16317 T, Viridibacillus arenosi DSM 16319 T were 61.0% and 32.1%, 60.0% and 33.1% based on the draft genome sequence. The results support the conclusion that strain YIM B01967T represents a novel species of the genus Viridibacillus, for which the name Viridibacillus soli sp. nov., is proposed. The type strain is YIM B01967T (= KCTC 43249 T = CGMCC 1.18436 T).

Propioniciclava soli sp. nov., isolated from forest soil, Yunnan, China, and reclassification of the genus Brevilactibacter into the genus Propioniciclava, and Brevilactibacter sinopodophylli, Brevilactibacter flavus, and Brevilactibacter coleopterorum as Propioniciclava sinopodophylli comb. nov., Propioniciclava flava comb. nov., and Propioniciclava coleopterorum comb. nov., respectively.

A Gram-stain-positive, coccus-shaped, facultatively anaerobic, non-motile bacterial strain, designated YIM S02567T, was isolated from a forest soil sample collected from Gejiu City, Yunnan Province, southwest PR China. Growth was observed at 10-45 °C, at pH 6.0-9.5, in the presence of up to 4.0% (w/v) NaCl on R2A medium. The results of 16S rRNA gene sequence similarity analysis showed that strain YIM S02567T was most closely related to the type strain of Brevilactibacter sinopodophylli (95.4%) and Propioniciclava tarda (94.7%), and phylogenetic analysis based on genome data showed that strain YIM S02567T should be assigned to the genus Propioniciclava. The cell-wall diamino acid was meso-diaminopimelic acid. The major cellular fatty acids were identified as anteiso-C15:0 and C16:0, and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and two unidentified glycolipids. The predominant menaquinone was MK-9(H4). The genomic DNA G + C content was 71.2 mol%. Based on the polyphasic taxonomic evidence, strain YIM S02567T is assigned to a novel member of the genus Propioniciclava, for which the name Propioniciclava soli sp. nov., (type strain YIM S02567T = CCTCC AB 2020128T = CGMCC 1.18504T = KCTC 49478T) is proposed. Furthermore, we propose the reclassification of Brevilactibacter as Propioniciclava gen. nov.

Optimized biosynthesis of santalenes and santalols in Saccharomyces cerevisiae.

Santalenes and santalols from Santalum album are the main components of the valuable spice sandalwood essential oil, which also has excellent pharmacological activities such as antibacterial, anti-inflammatory, and antitumor. Firstly, we constructed biosynthesis pathways of santalenes by synthetic biology strategy. The assembled biosynthetic cassettes were integrated into the multiple copy loci of δ gene in S. cerevisiae BY4742 with assistance of pDi-CRISPR, and 94.6 mg/L santalenes was obtained by shake flask fermentation of engineered yeast. Secondly, a selected optimized P450-CPR redox system was integrated into the chromosome of the santalenes-producing strain with a single copy, and 24.6 mg/L santalols were obtained. Finally, the yields of santalenes and santalols were increased to 164.7 and 68.8 mg/L, respectively, by downregulating ERG9 gene. This is the first report on the de novo synthesis of santalols by P450-CPR chimera in S. cerevisiae. Meanwhile, the optimized chimeric CYP736A167opt-46tATR1opt exhibits higher activity to oxidize santalenes into santalols. It would provide a feasible solution for the optimal biosynthesis of santalols. KEY POINTS: • First-time de novo synthesis of santalols by P450-CPR chimera in S. cerevisiae. • Truncated 46tATR1 has higher activity than that of CPR2. • Yields of santalenes and santalols were increased by downregulating ERG9 gene.

Functional Characterization of a New Bifunctional Terpene Synthase LpNES1 from a Medicinal Plant Laggera pter odonta.

Laggera pterodonta, known in China as 'Choulingdan' for its stimulous odor, has long been used as traditional herbal medicine. The essential oil of L. pterodonta, which exhibits various pharmacological activities, is a rich resource of monoterpenes and sesquiterpenes. To date, however, the terpene synthases responsible for their production remain unknown. In present study, a new terpene synthase gene (LpNES1) was identified from L. pterodonta, transcript level of which was significantly upregulated in response to methyl jasmonate treatment. Recombinant LpNES1 could synthesize (E)-nerolidol and minor ß-farnesene from farnesyl diphosphate and linalool from geranyl diphosphate in vitro. Whereas, only sesquiterpenes including (E)-nerolidol and minor ß-farnesene were released when LpNES1 was reconstituted in yeast, even coexpressed with a geranyl diphosphate synthase (ERG20WW). Combined with subcellular localization experiment, the result indicated that the cytosol-targeted LpNES1 was responsible for (E)-nerolidol biosynthesis exclusively in L. pterodonta. Additionally, the expression level of LpNES1 gene was more prominent in floral buds than that in other tissues. LpNES1 characterized in present study not only lays the molecular foundation for sesquiterpene biosynthesis of L. pterodonta, but provides a key element for further biosynthesis of bioactive compound in microbes.

Aestuariimicrobium ganziense sp. nov., a new Gram-positive bacterium isolated from soil in the Ganzi Tibetan autonomous prefecture, China.

A novel Gram-stain positive, oval-shaped, and non-flagellated bacterium, designated YIM S02566T, was isolated from alpine soil in Shadui Towns, Ganzi County, Ganzi Tibetan Autonomous Prefecture, Sichuan Province, PR China. Growth occurred at 23-35 °C (optimum, 30 °C) in the presence of 0.5-4% (w/v) NaCl (optimum, 1%) and at pH 7.0-8.0 (optimum, pH 7.0). The phylogenetic analysis based on 16S rRNA gene sequence revealed that strain YIM S02566T was most closely related to the genus Aestuariimicrobium, with Aestuariimicrobium kwangyangense R27T and Aestuariimicrobium soli D6T as its closest relative (sequence similarities were 96.3% and 95.4%, respectively). YIM S02566T contained LL-diaminopimelic acid in the cell wall. MK-9(H4) was the predominant menaquinone. The major fatty acid patterns were anteiso-C15:0 (60.0%). The major polar lipid was DPG. The genome size of strain YIM S02566T was 3.1 Mb, comprising 3078 predicted genes with a DNA G + C content of 69.0 mol%. Based on these genotypic, chemotaxonomic and phenotypic evidences, strain YIM S02566T was identified as a novel species in the genus Aestuariimicrobium, for which the name Aestuariimicrobium ganziense sp. nov. is proposed. The type strain is YIM S02566T (= CGMCC 1.18751 T = KCTC 49,477 T).

[Recent advances in biosynthesis of forskolin].

Forskolin is a complex labdane plant diterpenoid, which has been used in the treatment of a variety of diseases based on its activity as an activator of adenosine monophosphate(cAMP) cyclase. Natural forskolin exists only in the cork layer of the root of Coleus forskohlii. Due to the complexity of the extraction and chemical synthesis processes, the yield and purity of forskolin cannot meet commercial requirements. In recent years, with the rapid development of synthetic biology and the analysis and interpretation of many diterpene biosynthetic pathways, a new approach has been provided for the green production of forskolin. In this paper, the structure, activity, biosynthetic pathway and the heterologous biosynthesis of forskolin were reviewed. The problems and solutions in the heterologous biosynthesis of forskolin were also discussed and summarized, which will provide references for the construction of high-yielding forskolin engineering strains.

Cloning and Characterization of a Ginsenoside-Hydrolyzing α-L-Arabinofuranosidase, CaAraf51, From Cellulosimicrobium aquatile Lyp51.

Moutai Jiuqu is a famous aromatic raw material of Maotai flavor liquor in China. It is brewed at high temperature and contains many kinds of bacteria, molds, and yeasts. There are many useful glycoside hydrolases in these microfloras, from which efficient glycoside hydrolases can be screened for biotransformation of natural saponins. In this study, an α-L-arabinofuranosidase gene (CaAraf51, 1524 bp, 507 amino acid, 55.07 kDa, and pI = 4.8) was cloned from Cellulosimicrobium aquatile Lyp51, which was isolated from the Maotai Jiuqu. The CaAraf51 was heterogeneously expressed in E. coli BL21 (DE3) and purified by N-terminal His-tag with the Ni2+-affinity column chromatography. The results show that purified CaAraf51 has a 6.8-fold purification factor and specific activity of 15 U/mg. Under optimal conditions (pH 5.0, temperature 40 °C), kinetic parameters Km of CaAraf51 for pNPαAraf and Rc were 1.1 and 0.57 mM, the Vmax were 25 and 6.25 µmol/min/mg, respectively. 90% of 0.87 mg Rc substrate can be transformed by 9.6 U purified CaAraf51 in 1 mL reaction system under suitable conditions (30 °C, pH 7.5 phosphate buffer, 1 h). In addition, we also tested the effects of metal ions and chemical agents on the activity of CaAraf51. According to systematically studied its function and enzymatic properties, CaAraf51 has excellent value and potential of biotransformation Rc into Rd.

Repeated evolution of cytochrome P450-mediated spiroketal steroid biosynthesis in plants.

Diosgenin is a spiroketal steroidal natural product extracted from plants and used as the single most important precursor for the world steroid hormone industry. The sporadic occurrences of diosgenin in distantly related plants imply possible independent biosynthetic origins. The characteristic 5,6-spiroketal moiety in diosgenin is reminiscent of the spiroketal moiety present in anthelmintic avermectins isolated from actinomycete bacteria. How plants gained the ability to biosynthesize spiroketal natural products is unknown. Here, we report the diosgenin-biosynthetic pathways in himalayan paris (Paris polyphylla), a monocot medicinal plant with hemostatic and antibacterial properties, and fenugreek (Trigonella foenum-graecum), an eudicot culinary herb plant commonly used as a galactagogue. Both plants have independently recruited pairs of cytochromes P450 that catalyze oxidative 5,6-spiroketalization of cholesterol to produce diosgenin, with evolutionary progenitors traced to conserved phytohormone metabolism. This study paves the way for engineering the production of diosgenin and derived analogs in heterologous hosts.

A new pregnane steroid from cultures of Aspergillus versicolor.

A new pregnane steroid, named aspergillon A (1), together with two known compounds, (22E,24R)-ergosta-5,7,22-trien-3ß-ol (2) and (22E, 24R)-ergosta-4,6,8(14),22-tetraen-3-one (3) were isolated from cultures of the tin mine tailings-associated fungus Aspergillus versicolor. The new structure and absolute configuration were determined with the help of extensive spectroscopic analyses and quantum chemical calculations of the electronic circular dichroism (ECD) spectra.

A new cyclohexenone from the tin mine tailings-derived fungus Aspergillus flavus YIM DT 10012.

A new cyclohexenone, named phomaligol D (1), together with two known compounds, kojic acid (2) and phomaligol A (3) were isolated from the tin mine tailings-derived fungus Aspergillus flavus YIM DT 10012. Their structures were elucidated by detailed analysis of spectroscopic data.

[Progress in biosynthesis of santalene and santalol].

Santalene and santalol are the main components of valuable perfume sandalwood essential oil, and have good antibacterial, anti-oxidation and anti-tumor activities. Commercial sandalwood essential oil is mainly extracted from sandalwood tree that grows slowly and is difficult to cultivate. In addition, the extraction recovery of sandalwood essential oil from sandalwood tree is too low to meet the market demand. These factors make sandalwood essential oil expensive. An option is to use genetic engineering and molecular biological methods to heterologously express related synthase of santalene and santalol in microbial host. In this paper, the biosynthesis progress of santalene and santalol synthase, as well as the optimization of mevalonate metabolic pathways in the hosts are summarized. Furthermore, the strategies of applying protein engineering technology to carry out orthomutation of santalene synthase were also discussed, to provide reference for the optimal biosynthesis of santalene and santalol.