A plant mutant that simultaneously enhances a plant's adaptability to high temperatures and high light and its applications.

Abstract

This invention discloses a plant mutant that simultaneously enhances a plant's adaptability to high temperatures and high light, and its applications. It belongs to the field of plant genetic engineering technology. The plant mutant is a single-base mutation of ICMT5, specifically AT5G59500. The amino acid sequence of the ICMT5 protein is shown in SEQ ID NO.1. This invention obtains... icmt5 The mutant identified the chloroplast location of the ICMT5 protein and revealed its role in enhancing plant photosynthetic capacity and adaptability to high temperature and high light. This invention not only provides a new perspective for analyzing the chloroplast response to environmental stress and offers a new theoretical reference for future artificial photosynthesis simulation, but also has important application value for the breeding and improvement of stress-resistant crop varieties.

Description

Technical Field

[0001] This invention relates to the field of plant genetic engineering technology, specifically to a plant mutant that simultaneously enhances the plant's adaptability to high temperatures and high light, and its applications. Background Technology

[0002] In nature, the growth environment of plants is not static but constantly changing. Therefore, plants need to adjust their own state in a timely manner to cope with a series of abiotic stresses (drought, heat, low temperature, salinity, high light, etc.) and biotic stresses (pathogen invasion, attack by herbivorous insects). These stresses severely limit crop yield (Fedoroff NV, Battisi DS, Beachy RN, Cooper PJ, Fischhoff DA, Hodges CN, Knauf VC, Lobell D, Mazur BJ, Molden D, Reynolds MP, Ronald PC, Rosegrant MW, Sanchez PA, Vonshak A, Zhu JK. Radically rethinking agriculture for the 21st century. Science. 2010, 327:833-834.). Chloroplasts are an important site for photosynthesis in plants. They can not only independently carry out DNA replication, RNA transcription, and protein translation (Allen JF. Translating photosynthesis. Nat Plants. 2018, 4: 199-200.), but also regulate plant stress adaptation by sensing stress signals, synthesizing active compounds, and initiating retrograde signals to link with the cell nucleus. They play an important role in plants' response to abiotic and biotic stresses (Zhang Y, Zhang A, Li X, Lu C. The Role of Chloroplast Gene Expression in Plant Responses to Environmental Stress. Int J Mol Sci. 2020, 21: 6082.).

[0003] Adverse environmental stresses reduce photosynthetic rates, significantly impacting plant growth and development, ultimately leading to severe yield and economic losses. Recent research has yielded substantial progress in areas such as chloroplast retrograde pathway signaling and the improvement of stress-resistant plant varieties (Song Y, Feng L, Alyafei MAM, Jaleel A, Ren M. Function of Chloroplasts in Plant Stress Responses. Int J Mol Sci. 2021, 22: 13464.). However, further research is needed to understand how abiotic stress triggers retrograde chloroplast signaling and how to improve plant varieties with minimal intervention to enhance overall stress resilience. Therefore, elucidating the environmental adaptation mechanisms of chloroplasts under stress and identifying key factors for crop variety improvement are crucial for plants to resist environmental stresses. Summary of the Invention

[0004] Technical problem to be solved: The technical problem to be solved by this application is the abnormal growth and development of plants caused by high temperature and high light stress, which leads to a decline in yield and quality. Based on the shortcomings of the existing technology, this application provides a plant mutant that simultaneously improves the plant's adaptability to high temperature and high light and its application.

[0005] Purpose of the invention: This application provides a plant mutant that simultaneously enhances a plant's adaptability to high temperatures and high light, and its applications. icmt5 The mutant was identified, and the chloroplast localization of the ICMT5 protein was determined. The results revealed that the mutant enhances the photosynthetic capacity and adaptability to high temperature and high light in plants. This not only provides a new perspective on the chloroplast response to environmental stress and offers a new theoretical reference for future artificial simulation of photosynthesis, but also has important application value for the breeding and improvement of stress-resistant crop varieties.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a plant mutant that simultaneously improves the plant's adaptability to high temperature and high light, wherein the plant mutant is a mutant of ICMT5, namely AT5G59500 single base mutation, and the amino acid sequence of the ICMT5 protein is shown in SEQ ID NO.1.

[0007] As a preferred technical solution of this application, the ICMT5 protein is encoded. ICMT5 The nucleotide sequence of the AT5G59500 gene is shown in SEQ ID NO.2.

[0008] Biological materials containing any of the plant mutants described above, wherein the biological material is an expression vector or a bacterial strain.

[0009] Application of any of the above-described plant mutants in improving plant photosynthetic capacity.

[0010] Application of any of the above-described plant mutants in simultaneously improving the plant's adaptability to high temperature and high light.

[0011] Application of any of the above-described plant mutants in the process of protein isoprene modification.

[0012] This application also discloses the application of any of the above-described plant mutants in the preparation of products that simultaneously improve the plant's adaptability to high temperatures and high light.

[0013] The plant mutant and its application described in this application, which simultaneously enhance the plant's adaptability to high temperatures and high light, have the following technical advantages compared to existing technologies: 1. This invention obtains a phenotype with severely yellowed leaves through forward genetics. Fv / Fm Normal mutants are named srps17-10 ; 2. After determining that the mutation was a recessive mutation controlled by a single gene, this invention performed map-based cloning and high-throughput sequencing on the gene to identify... srps17-10 The mutated gene in the double mutation is AT5G59500 and named it ICMT5 ; 3. The mutation site of this invention involves a single base change at 23.986464M of the gene, from C to A, resulting in the mutation of the 147th amino acid encoded by it from serine (Ser) to arginine (Arg). 4. In this invention, the ICMT5 protein is located on the outer membrane of chloroplasts. icmt5 The mutant exhibits dark green leaves with normal fluorescence, and photosynthetic indicators such as chlorophyll content, chlorophyll fluorescence curve, and content of various subunit proteins of thylakoid membrane complex are all increased. 5. This invention can withstand high temperature and high light stress conditions. icmt5 The mutants exhibited stronger resistance to adverse conditions; 6. The lipidomics analysis of this invention shows that, icmt5 The mutant showed a significant accumulation of metabolites from the steroid biosynthesis pathway, such as stigmasterol, sitosterol, and campesterol. 7. Proteomics analysis of this invention shows that, icmt5 The isoprene C-terminal methyltransferase-related homologues were generally upregulated in the mutant; 8. This invention provides an important target for elucidating the molecular network of plant chloroplasts in response to environmental stress, and offers innovative ideas for agricultural research fields such as crop variety improvement and grain yield increase. Attached Figure Description

[0014] Figure 1 This is the present invention. icmt5 Mutant gene clones, mutation sites, and phenotypic diagrams, where A represents the exchange values ​​at each marker in the map-based clones; B represents the high-throughput sequencing results; and C represents the results of high-throughput sequencing. icmt5 A schematic diagram of the mutant mutation sites and the corresponding sequencing peak diagram, with red boxes representing mutation sites; Figure 2 This is the present invention. icmt5 Phenotypic and chlorophyll content determination, where A represents wild type (WT) and icmt5 The phenotypes of the mutants cultured on petri dishes for 7 days and in soil for 25 days; B represents the WT and... icmt5 Results of chlorophyll content determination of mutants after 7 days of culture in petri dishes; Figure 3 This is a subcellular localization map of the ICMT5 protein of the present invention, wherein A is the transient fluorescence localization of ICMT5 protein expression; B is the detection result of different components of intact chloroplasts separated by sucrose density gradient centrifugation and using specific antibodies; Stroma represents chloroplast stroma, OEM represents chloroplast outer membrane, IEM represents chloroplast inner membrane, Rbcl is chloroplast stroma control protein, Toc75 is chloroplast outer membrane control protein, and Tic40 is chloroplast inner membrane control protein; Figure 4 This invention is icmt5 Results of chlorophyll fluorescence curve determination in mutants and abundance detection of proteins in various subunits of the thylakoid membrane complex, where A represents... icmt5 The photoresponse curve of the mutant was measured, and the measured parameters included the actual quantum yield Y(II) of photosystem II, the electron transport rate ETR, the non-photochemical quenching parameter NPQ, and the non-photochemical quenching quantum yields Y(NPQ) and Y(NO); B is... icmt5 The mutant contains PSI (PsaA), PSII (core proteins D1, D2, antenna proteins CP43, CP47, PsbO), LHCI (Lhca4), LHCII, and Cyt. b6f (Cyt b6 Results of protein content detection, including ATP; Figure 5 This is the present invention. icmt5 The results of high temperature and high light stress treatment on the mutant are shown in the figure, where A is... icmt5 Statistical analysis of the phenotype and lethality of mutants treated at 45℃ for 3 hours and recovered for 3 days, with B being... icmt5 In vitro light-inhibition and light-recovery phenotypes of mutants, C is icmt5 In vitro photoinhibition and photorecovery of mutants Fv / Fm Value statistics; Figure 6 This is a diagram of significantly differentially metabolized metabolites and metabolic pathways in lipidomics according to the present invention, where A is... icmt5 Differential metabolites with upregulated content and smallest P-value in mutants; B represents metabolites from Figure A substituted into the KEGG metabolic pathway, with phytosterol products in the red box and red arrows indicating changes in phytosterol product content. Figure 7 This invention relates to proteomics. icmt5 The upregulated proteins in the mutants and their enrichment locations in the mevalonate pathway, where A is... icmt5 The mutant protein is upregulated; B indicates the enrichment location of upregulated S-adenosine-L-methionine-dependent methyltransferase superfamily proteins in the mevalonate pathway; the green box shows the representative enzyme of this step; the red box shows the upregulated ICMT5 homologue protein; and the red solid arrow indicates the content change. Detailed Implementation

[0015] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0016] A plant mutant that simultaneously enhances a plant's adaptability to high temperatures and high light, wherein the plant mutant is a single-base mutation of ICMT5, specifically AT5G59500, and the amino acid sequence of the ICMT5 protein is shown in SEQ ID NO.1: MEAVLLLCSKLVPRAASLEGNQKFSFRHLNKHLKCNSLRADSRDTPLLRGFEAIKSPSIWSCAPFPVRKGSWVPPRCSISSSTVSDSDNPFLSQFRTFSFGSMVKKVRELKVKPMDVVKLTLLLSILTVAAKKTLTLVLDPFFWMYFSWTWLFWPWFIAVGLAGYGIYCFRKHWLGEANAFEQLGIVTSVFTWLTLVPP AYFNGYLEGWPYVFFLAYHYFFFFNVSVRKRLYGDFYARTHDPKWDVNTPLWSRILFGVGIMVGHWLAAFEGPELHRLPGGWANVGIWILIVITMLMHY DSTLYLARYSEKVVVPTAVVQFGPYRWVRHPIYASTMLLFAAYCTALRAPLSLLFLLAVCLVYYNKKAKMEEELMVESFGQSYSDYADKVRHKFIPFVY.

[0017] Encoding ICMT5 protein ICMT5 The nucleotide sequence of the AT5G59500 gene is shown in SEQ ID NO.2:

[0018] Example 1, icmt5 Acquisition and phenotype of mutants: This embodiment first inserts commercially available T-DNA. rps17 (AT1G79850, SALK_066943) seeds were used for homozygosity verification and propagation (verification primers LP as shown in SEQ ID NO.3: AAGACAACAAATCATCGGCAC, primers RP as shown in SEQ ID NO.4: CCTTTTCCAGTCTGACCACG, primers LB as shown in SEQ ID NO.5: ATTTTGCCGATTTCGGAAC). Subsequently, 10 g of homozygous seeds were taken. rps17 Seeds were subjected to EMS (Ethylmethanesulfonate) mutagenesis treatment, and the mutagenized seeds were inoculated into MS medium. F1 generation seeds were harvested in a mixture, and F2 generation seeds were harvested individually to ultimately construct a pool containing 100 mutants. rps17 EMS mutant library.

[0019] right rps17 The EMS mutant library is based on phenotype and Fv / Fm Two criteria were used for screening, and one plant with a phenotype superior to WT and WT was found. rps17 Weak, with relatively small leaves rps17 Intense yellowing, and Fv / Fm Plants that appear normal, with results as follows Figure 2 As shown in Figure A. This plant was isolated and cultured separately, and denoted as […]. suppressor rps17-10 mutants, hereinafter referred to as srps17-10 Mutant.

[0020] Selected plants that have been cultured in soil for 50 days srps17-10 The mutants were respectively with L er Ecological rps17 The mutants were hybridized and backcrossed. After background validation on the F1 generation plants from the hybridization and backcrossing, a total of 1588 plants were counted in the F2 generation. These plants passed background validation and... Fv / Fm The phenotypes were determined and divided into three categories, and the proportion of each type in the population was calculated, as shown in Table 1. Among them, 1186 plants had WT background and normal fluorescence. rps17 300 plants with mutant background and high fluorescence. rps17 102 plants with a mutant background and normal fluorescence were observed. The segregation ratio was calculated to be approximately 12:3:1 (where 12 represents the total number of homozygous and heterozygous plants against the WT background), indicating... srps17-10 The segregation ratio of the F2 generation of the mutant hybrids conforms to Mendel's law of independent assortment.

[0021] Table 1

[0022] .

[0023] A total of 945 plants were counted in the backcross F2 generation, and background validation and... Fv / Fm The phenotypic segregation was determined and divided into two categories, as shown in Table 1. Among them, rps17 There were 716 plants with a mutant background and high fluorescence. rps17 There were 229 plants with mutant background and normal fluorescence, with a segregation ratio of approximately 3:1 (where 3 represents the sum of homozygous and heterozygous plants in the WT background).

[0024] illustrate srps17-10 The segregation ratio in the F2 generation of the backcross of the mutant conforms to Mendel's law of segregation. These results indicate... srps17-10 Mutants are recessive mutations controlled by a single gene.

[0025] In clear srps17-10 After identifying the mutant as a recessive mutation controlled by a single gene, coarse mapping of the mutated gene was performed. From srps17-10 mutant and L er Ninety plants were selected from the F2 generation of the hybrids. rps17 Plants with a mutant background and normal fluorescence were subjected to PCR amplification using 3-4 pairs of mapping primers evenly selected at different locations on chromosome IV, as shown in Tables 2-1 and 2-2. After 3×TBE agarose gel electrophoresis, three band patterns were observed: a smaller single band (homozygous WT type), a larger single band (homozygous L type), and a larger single band. er The results show that the two bands (hybrid type) contain both large and small bands. Figure 1 As shown in Figure A, the exchange rate at chromosome 5 at 23.86 M and 25.19 M is 1.43%, and the exchange rate at the midpoint of this interval, 24.01 M, is close to 0. It is speculated that the mutation site is located in the interval of 23.86 M-25.19 M on chromosome 5, and is infinitely close to 24.01 M.

[0026] Table 2-1 .

[0027] Table 2-2 .

[0028] Next, high-throughput sequencing was used to precisely locate the mutated gene. From srps17-10 mutants and rps17 78 strains were selected from the F2 generation of the mutant backcross. rps17 Plants with mutant background and normal fluorescence underwent high-throughput sequencing of their whole genome DNA. Results are as follows: Figure 1As shown in Figure B, a single base mutation occurs at position 23.986464 M on chromosome 5, changing the base from C to A, resulting in the amino acid encoded at position 147 changing from serine (Ser) to arginine (Arg).

[0029] To verify the cloned ICMT5 Genes and srps17-10 The correspondence between mutant phenotypes will, in turn, ICMT5 Gene replacement to s rps17-10 In the mutant. The results are as follows: Figure 2 As shown in Figure A, the leaf color of homozygous recombinant positive seedlings is relatively... srps17-10 The mutant turned significantly green, and rps17 The mutants have uniform leaf color; at the same time, their Fv / Fm Also restored to the same rps17 The mutant exhibits the same high fluorescence state. This result indicates that... srps17-10 The yellowing phenotype of the mutant is indeed caused by ICMT5 Caused by gene mutation.

[0030] Then srps17-10 The mutant was crossed with WT, and the high-fluorescence plants were removed in the F2 generation. rps17 Mutant background verification removal rps17 The mutant background plants were used to further investigate the remaining 60 WT background plants. ICMT5 Sequencing analysis of the whole genome sequence from 23986301 to 23986701 (23986301-F as shown in SEQ ID NO.52: 5'-AATTTCGAACCTTCTCTTTT-3', 23986701-R as shown in SEQ ID NO.53: 5'-CTCCATAGAGGCGTTTTCTC-3') revealed 18 plants with a CA base mutation at the 23986464 mutation site and a single peak in the sequencing profile; these were the isolated plants. icmt5 Single mutant. Results are as follows: Figure 1 C, Figure 2 China A Figure 2 As shown in B, icmt5 The mutant seedlings had darker green leaves than the WT mutant, but the plant size was not significantly different from the WT mutant. icmt5 mutant Fv / Fm Consistent with WT, both showed normal fluorescence.

[0031] Example 2, Subcellular localization of ICMT5 protein: The CDS sequence of the ICMT5 protein was cloned into the transient expression vector pUC18-GFP, and the GFP fluorescence distribution was observed using laser confocal microscopy. The results are as follows: Figure 3As shown in Figure A, when Toc33-RFP was transformed alone, red fluorescence was distributed in a dotted pattern on the outer chloroplast membrane; when Tic20-RFP was transformed alone, red fluorescence was evenly distributed on the inner chloroplast membrane; and when ICMT5-GFP was transformed alone, green fluorescence was concentrated on the chloroplast membrane and distributed in a dotted pattern. Co-transformation of ICMT5-GFP and Toc33-RFP revealed that their fluorescence distributions completely overlapped.

[0032] The chloroplast stroma, outer membrane, and inner membrane components were then separated by sucrose density gradient centrifugation and detected using specific antibodies. The results are as follows: Figure 3 As shown in Figure B, ICMT5 protein is mostly enriched in the outer chloroplast membrane component, and its distribution is completely consistent with that of the outer chloroplast marker protein Toc75; a small amount of ICMT5 protein was also detected on the inner chloroplast membrane. In summary, ICMT5 is located on the outer chloroplast membrane.

[0033] Example 3, icmt5 The mutant exhibits enhanced photosynthetic capacity: right icmt5 The mutants underwent chlorophyll fluorescence curve measurements, including indicators such as Y(II), NPQ, ETR, Y(NPQ), and Y(NO). The results are as follows: Figure 4 As shown in A, icmt5 The mutant's actual quantum yield Y(II) of photosystem II shows an upward trend compared to WT, especially when the light intensity is greater than 600 μmol m -2 s -1 At that time, the increase in Y(II) accelerated significantly, indicating that icmt5 The mutant exhibits better light energy conversion efficiency than the WT mutant. Furthermore, it performs better under light intensities greater than 600 μmol m... -2 s -1 hour, icmt5 The mutant's electron transport rate (ETR) was significantly higher than that of the WT, indicating that its photosynthetic electron transport efficiency was higher. icmt5 The mutant also showed a significant increase in the non-photochemical quenching parameter NPQ, indicating that... icmt5 The mutant can more effectively remove excess light energy through heat dissipation under strong light, thereby reducing the risk of damage to the optical system. icmt5 The mutant's Y (NO) level was significantly lower than that of the WT, indicating that it can effectively avoid photo-oxidative damage caused by excess light energy by enhancing electron transfer efficiency and heat dissipation.

[0034] To further explore icmt5 The changes in the protein content of each subunit of the thylakoid membrane complex in the mutant, and icmt5 The mutants were subjected to Western blot analysis. The results are as follows: Figure 4 As shown in B, icmt5The levels of D1 and D2 proteins in the PSII reaction center of the mutant were increased compared to the WT, exceeding the WT level by approximately 50%. icmt5 The content of light-harvesting antennae CP43 and CP47 in the mutant was also higher than that in WT, about 10-30% higher; icmt5 The mutants have the following light-harvesting antennas: PSI (LHCI), PSII (LHCII), and Cyt. b6f The content of ATP complex subunits was also higher than that of WT. These results indicate that... icmt5 The content of proteins in each subunit of the thylakoid membrane complex involved in photosynthesis was generally upregulated in the mutant.

[0035] Example 4, icmt5 The mutant responds to high temperature and high light stress: Selected cultured petri dishes after 7 days of growth icmt5 The mutants were subjected to high-temperature stress treatment, placed in a 45℃ dark incubator for 3 hours, and then transferred to 22℃ normal light conditions for recovery for 3-4 days. Phenotypic characteristics were observed and survival rates were calculated. Results are as follows: Figure 5 As shown in Figure A, after being subjected to high-temperature stress at 45℃, icmt5 The survival rate of the mutant plants was about twice that of the WT plants, indicating that they were more resistant to high temperatures than the WT plants.

[0036] They were then cultured in soil for 30 days. icmt5 The mutant was subjected to high-in vitro leaf treatment, and leaf fluorescence images were acquired using the Fluor Cam chlorophyll fluorescence imaging system at 0, 0.5, 1, 2, and 4 h, respectively, and the fluorescence at each time point was statistically analyzed simultaneously. Fv / Fm The result is as follows Figure 5 B, Figure 5 As shown in Figure C, after 0.5 h of highlight processing, icmt5 The leaves in the mutant remained in a normal fluorescent state, while only 3 leaves in the WT remained in a normal fluorescent state; with the extension of the high-light treatment time, icmt5 mutants at various treatment time gradients Fv / Fm It was always higher than WT until 4 hours after highlighting, when WT and icmt5 The fluorescence differences among mutants were most pronounced at this time, in the leaves of WT. Fv / Fm It is around 0.3, while icmt5 Three leaves in the mutant still exhibit intermediate green fluorescence. Fv / Fm It is around 0.45, significantly higher than WT. In summary, icmt5 The mutant exhibited a smaller decrease in fluorescence value under high light stress and its photosystem stability was significantly better than that of the WT mutant, confirming that it has stronger high light tolerance.

[0037] After highlighting, icmt5 The mutant was exposed to light with an intensity of 40 μmol m-2 s -1 Photorecovery was performed under illumination from both sides, and fluorescence images were acquired and statistically analyzed at 0, 1, 2, 3, and 4 hours. Fv / Fm The result is as follows Figure 5 B, Figure 5 As shown in Figure C, after 0.5 h of light recovery, icmt Of the 6 leaves in mutant 5, 3 recovered to normal fluorescence, and the remaining 3 recovered to green fluorescence, while in WT, 5 leaves only recovered to green fluorescence. As the light recovery time increased, icmt5 The mutant fluorescence recovery rate was significantly faster than that of the WT mutant, until 5 hours after recovery. Fv / Fm It was restored to its pre-highlighting level; while WT, even after 5 hours of recovery, Fv / Fm It has not yet fully recovered to its initial level. The above results indicate that... icmt5 The mutants were able to initiate photosystem repair mechanisms more quickly after high light stress, shortening the duration of stress damage and demonstrating stronger recovery ability under high light stress.

[0038] Example 5, icmt5 Mutant omics analysis: Select WT and 10 days of growth on a petri dish icmt5 Mutant plants were weighed out in 2 mL centrifuge tubes (0.1 g each), with each sample repeated four times. After inactivation with an appropriate amount of inactivating agent, lipidomics analysis was performed. Results are as follows: Figure 6 As shown in Figure A, stigmasterol esters (Stigma, Stigma-18:2, Stigma-18:3, Stigma-16:1), sitosterylesters (Sitosterylesters, Sito-18:3, Sito, Sito-16:1), steryl esters, and campesterylesters were the top 10 significantly different metabolites with the smallest P-values, and these metabolites were... icmt5 All four metabolites were upregulated in the mutants. A search on the KEGG pathway website revealed that these four metabolites belong to the same metabolic pathway, are downstream products of the steroid synthesis pathway, and that the upstream pathway of this pathway starts with farnesyl pyrophosphate (FPP). The results are as follows... Figure 6 As shown in B.

[0039] Select WT and 10-day-old cultured plants grown on petri dishes icmt5 For mutant plants, appropriate amounts of material were weighed and plant total protein was extracted. Each sample was analyzed in triplicate, with a concentration of 10 μg / μL, followed by proteomics analysis. Results are as follows: Figure 7As shown in Figure A, Q9LZA4, A0A1P8AQT8, and Q8LBV4 are S-adenosyl-L-methionine-dependent methyltransferase superfamily proteins, also known as SAM-dependent methyltransferases. icmt5 The mutants showed significant upregulation, upregulating to approximately 5-fold, 2.5-fold, and 2-fold of WT, respectively, and these proteins were enriched at methyltransferases in the mevalonate pathway, as shown in the results. Figure 7 As shown in Figure B, one pathway for protein isopreneation is the mevalonate pathway, which also uses farnesyl pyrophosphate (FPP) as the starting material. SAM-dependent methyltransferase family proteins also typically participate in protein isopreneation, transferring methyl groups from the S-adenosylmethionine (SAM) methyl donor to the cysteine ​​residue at the protein's carboxyl terminus, thereby affecting protein localization, signal transduction, and other vital processes. In conclusion, ICMT5 may participate in protein isopreneation as a SAM-dependent methyltransferase.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

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