AIM: To investigate the molecular mechanism for regulation of cholesterol metabolism by hepatitis C virus(HCV) core protein in Hep G2 cells.METHODS: HCV genotype 1b core protein was cloned and expressed in Hep G2 cell...AIM: To investigate the molecular mechanism for regulation of cholesterol metabolism by hepatitis C virus(HCV) core protein in Hep G2 cells.METHODS: HCV genotype 1b core protein was cloned and expressed in Hep G2 cells. The cholesterol content was determined after transfection. The expression of sterol regulatory element binding protein 2(SREBP2) and the rate-limiting enzyme in cholesterol synthesis(HMGCR) was measured by quantitative real-time PCR and immunoblotting after transfection. The effects of core protein on the SREBP2 promoter and 3'-untranslated region were analyzed by luciferase assay. We used different target predictive algorithms, micro RNA(mi RNA) mimics/inhibitors, and site-directed mutation to identify a putative target of a particular mi RNA.RESULTS: HCV core protein expression in Hep G2 cells increased the total intracellular cholesterol level(4.05 ± 0.17 vs 6.47 ± 0.68, P = 0.001), and this increase corresponded to an increase in SREBP2 and HMGCR m RNA levels(P = 0.009 and 0.037, respectively) and protein expression. The molecular mechanism studyrevealed that the HCV core protein increased the expression of SREBP2 by enhancing its promoter activity(P = 0.004). In addition, mi R-185-5p expression was tightly regulated by the HCV core protein(P = 0.041). Moreover, overexpression of mi R-185-5p repressed the SREBP2 m RNA level(P = 0.022) and protein expression. In contrast, inhibition of mi R-185-5p caused upregulation of SREBP2 protein expression. mi R-185-5p was involved in the regulation of SREBP2 expression by HCV core protein. CONCLUSION: HCV core protein disturbs the cholesterol homeostasis in Hep G2 cells via the SREBP2 pathway; mi R-185-5p is involved in the regulation of SREBP2 by the core protein.展开更多
采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、双抗夹心酶联免疫吸附(enzyme-linked immunosorbent assay,ELISA)等方法,以Jug r 1含量为指标,对云南7个不同产地的泡核桃(Juglans sigillata)进行筛选,进一步利用硫酸铵分级沉淀、凝胶过滤层...采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、双抗夹心酶联免疫吸附(enzyme-linked immunosorbent assay,ELISA)等方法,以Jug r 1含量为指标,对云南7个不同产地的泡核桃(Juglans sigillata)进行筛选,进一步利用硫酸铵分级沉淀、凝胶过滤层析、液相色谱-串联质谱等手段制备Jug r 1并进行优化和鉴定,通过圆二色谱对Jug r 1的结构进行表征,最后采用双抗夹心ELISA法测定其含量。结果表明:保山隆阳产地核桃的总蛋白含量和Jug r 1含量均最高,用于后续实验;经优化得到Jug r 1的最佳硫酸铵分级沉淀分离区间为40%~80%,进一步对其进行凝胶过滤层析的最佳条件为上样质量浓度30 mg/mL、上样体积4 mL、洗脱流速1 mL/min;在此条件下纯化得到Jug r 1含量达19.90 mg/120 mg上样量,蛋白得率为16.58%;质谱分析表明该蛋白符合Jug r 1的典型特征;圆二色谱显示Jug r 1的二级结构以α-螺旋为主,多种构象共存;经“两步法”分离纯化后可获得蛋白纯度占总蛋白96%以上的Jug r 1。本结果可为深入研究Jug r 1提供科学基础,并为其他坚果致敏蛋白的分离纯化提供参考。展开更多
An improved CBB staining with higher sensitivity than that of the typical CBB staining was reported.The main improvement was using a fixing step of 25% trichloroacetic acid(TCA) before CBB staining.For most proteins s...An improved CBB staining with higher sensitivity than that of the typical CBB staining was reported.The main improvement was using a fixing step of 25% trichloroacetic acid(TCA) before CBB staining.For most proteins studied,the sensitivity of the improved CBB staining was about twice as high as that of the typical method.For basic and low molecular weight proteins such as ribosomal proteins,the sensitivity of this improved staining method was about 3.5-28 times that of the typical method.It was speculated that the improved procedure would be suitable for exact quantitative analysis of proteins fractionated by SDS-PAGE,especially for basic and low molecular weight proteins.On the other hand,this new modified method might be also applied to multidisciplinary studies,such as biological researches and nuclear sciences.展开更多
Viral protein R(Vpr) plays an important role in the replication and pathogenesis of Human immunodeficiency virus type 1(HIV-1). Some of the various functions attributed to Vpr, including the induction of G2/M cell cyc...Viral protein R(Vpr) plays an important role in the replication and pathogenesis of Human immunodeficiency virus type 1(HIV-1). Some of the various functions attributed to Vpr, including the induction of G2/M cell cycle arrest, activating the NF-κB pathway, and promoting viral reverse transcription, might be interrelated. To test this hypothesis, a panel of Vpr mutants were investigated for their ability to induce G2/M arrest and to activate the NF-κB pathway. The results showed that the Vpr mutants that failed to activate NF-κB also lost the activity to induce G2/M arrest, which suggests that inducing G2/M arrest via Vpr depends at least partially on the activation of NF-κB. This latter possibility is supported by data showing that knocking down the key factors in the NF-κB pathway – p65, Rel B, IKKα, or IKKβ– partially rescued the G2/M arrest induced by Vpr.Our results suggest that the NF-κB pathway is probably involved in Vpr-induced G2/M cell cycle arrest.展开更多
AIM: To investigate the roles and interactions of rhoassociatedprotein kinase (ROCK)1 and miR-124 inhuman colorectal cancer (CRC).METHODS: Expression of ROCK1 protein wasexamined by Western blotting, and quantitativer...AIM: To investigate the roles and interactions of rhoassociatedprotein kinase (ROCK)1 and miR-124 inhuman colorectal cancer (CRC).METHODS: Expression of ROCK1 protein wasexamined by Western blotting, and quantitativereverse transcriptase PCR was performed to measureexpression of ROCK1 mRNA and miR-124. Two cancercell lines were transfected with pre-miR-124 (mimic)and anti-miR-124 (inhibitor) and the effects onROCK1 protein and mRNA expression were observed.In addition, cell proliferation was assessed via a5-ethynyl-2′ deoxyuridine assay. Soft agar formationassay, and cell migration and invasion assays wereused to determine the effect of survivin on thetransformation and invasion activity of CRC cells.RESULTS: miR-124 was significantly downregulated inCRC compared to normal specimens (0.603 ± 0.092 vs1.147 ± 0.286, P = 0.016) and in metastatic comparedto nonmetastatic CRC specimens (0.416 ± 0.047 vs0.696 ± 0.089, P = 0.020). Expression of miR-124 wassignificantly associated with CRC metastasis, tumor Tand N stages, and tumor grade (all P < 0.05). ROCK1protein was significantly increased in CRC comparedto normal tissues (1.896 ± 0.258 vs 0.866 ± 0.136,P = 0.026), whereas ROCK1 mRNA expression wasunaltered (2.613 ± 0.251 vs 2.325 ± 0.246). miR-124and ROCK1 were inversely expressed in CRC tissuesand cell lines. ROCK1 mRNA was unaltered in cellstransfected with miR-124 mimic and miR-124 inhibitor,compared to normal controls. There was a significantreduction in ROCK1 protein in cells transfected withmiR-124 mimic and a significant increase in cells transfected with miR-124 inhibitor (P s < 0.05).Transformation and invasion of cells transfectedwith miR-124 inhibitor were significantly increasedcompared to those in normal controls (P < 0.05). Cellstransfected with miR-124 inhibitor showed increasedcell proliferation.CONCLUSION: miR-124 promotes hyperplasia andcontributes to invasion of CRC cells, but downregulatesROCK1. ROCK1 and miR-124 may play important rolesin CRC.展开更多
AIM To determine the association of human antigen R(HuR) and inhibitors of apoptosis proteins(IAP1, IAP2) and prognosis in pancreatic cancer.METHODS Protein and mRNA expression levels of IAP1, IAP2 and HuR in pancreat...AIM To determine the association of human antigen R(HuR) and inhibitors of apoptosis proteins(IAP1, IAP2) and prognosis in pancreatic cancer.METHODS Protein and mRNA expression levels of IAP1, IAP2 and HuR in pancreatic ductal adenocarcinoma(PDAC) were compared with normal pancreatic tissue. The correlations among IAP1/IAP2 and HuR as well as their respective correlations with clinicopathological parameters were analyzed. The Kaplan-Meier method and log-rank tests were used for survival analysis. Immunoprecipitation assay was performed to demonstrate HuR binding to IAP1, IAP2 mRNA. PANC1 cells were transfected with either anti-HuR siRNA or control siRNA for 72 h and quantitative reverse transcription polymerase chain reaction(RT-PCR), western blot analysis was carried out.RESULTS RT-PCR analysis revealed that HuR, IAP1, IAP2 mRNA expression were accordingly 3.3-fold, 5.5-fold and 8.4 higher in the PDAC when compared to normal pancreas(P < 0.05). Expression of IAP1 was positively strongly correlated with HuR expression(P < 0.05, r = 0.783). Western blot analysis confirmed RTPCR results. High IAP1 expression, tumor resection status, T stage, lymph-node metastases, tumor differentiation grade, perineural and lymphatic invasion were identified as significant factors for shorter survival in PDAC patients(P < 0.05).Immunohistological analysis showed that HuR was mainly expressed in the ductal cancer cell's nucleus and less so in cytoplasm. RNA immunoprecipitation analysis confirmed IAP1 and IAP2 post-transcriptional regulation by HuR protein. Following siHuR transfection, IAP1 mRNA and protein levels were decreased, however IAP2 expression levels were increased.CONCLUSION HuR mediated overexpression of IAP1 significantly correlates with poor outcomes and early progression of pancreatic cancer. Further studies are needed to assess the underlying mechanisms.展开更多
Plants, just like any other living organism, naturally get attacked by various pathogenic microorganisms such as bacteria, fungi and viruses. However, unlike animals that utilize their specialized circulatory macropha...Plants, just like any other living organism, naturally get attacked by various pathogenic microorganisms such as bacteria, fungi and viruses. However, unlike animals that utilize their specialized circulatory macrophage system to protect themselves, plants instead use a multi-layered complex system termed the plant innate immunity, which recognizes pathogens and transducing downstream defense responses. They have developed a unique type of trans-membrane receptors or R proteins, which extracellularly, are capable of recognizing pathogen-associated molecular patterns (PAMP) such as flagellin and chitin, while intracellularly, they activate their harbored nucleotide cyclases (NCs) such as adenylyl cyclases (ACs), to generate second messenger molecules such as 3’,5’-cyclic adenosine monophosphate (cAMP), which then propagates and magnifies the defense response. To date, only a single R protein from Arabidopsis thaliana (AtLRR) has been shown to possess AC activity as well as having the ability to defend plants against infection by biotrophic and hemi-biotrophic pathogens. Therefore, in order to further broaden information around the functional roles of this protein (AtLRR), we explored it further, using an array of web-based tools or bioinformatics. These included structural analysis, anatomical expression analysis, developmental expression analysis, co-expression analysis, functional enrichment analysis, stimulus-specific expression analysis and promoter analysis. Findings from structural analysis showed that AtLRR is a multi-domain, trans-membrane molecule that is multi-functional, and thus consistent with all known R-proteins. Findings from anatomical and developmental expression analyses showed that AtLRR is mostly expressed in pollen grains and flowers, senescing leaves as well as during the development of seeds, shoots, roots, seedlings, leaves, flowers, and siliques, linking it to the three key plant physiological processes of reproduction, defense and development respectively. Lastly, findings from co-expression, functional enrichment, stimulus-specific expression and promoter analyses, showed that AtLRR is mostly co-expressed with several other proteins linked to disease resistance, plant reproduction and plant development. Activities and functions of such protein are also commonly regulated by cAMP via a common W-box promoter. So, all in all, our study managed to establish that besides being strongly involved in disease resistance against biotrophic and hemi-biotrophic pathogens, AtLRR also plays key roles in plant development (seed, shoot, root, seedling, leaf, and silique development) and reproduction (flowering, and pollen tube growth and re-orientation), whereby it effects its functions via a W-box or WRKY transcription factor, TTGACY, mediated by cAMP.展开更多
SsrA peptide tag from Mycoplasma fl orum has been developed as a versatile biotechnology tool to control orthogonal degradation of tagged proteins in Escherichia coli . Here, using the systematic deletion mutants of m...SsrA peptide tag from Mycoplasma fl orum has been developed as a versatile biotechnology tool to control orthogonal degradation of tagged proteins in Escherichia coli . Here, using the systematic deletion mutants of mf -ssrA tag, we demonstrated that the residues in two separate regions have diff erent functions in mf -Lon-mediated specifi c orthogonal target protein degradation in E. coli . The deletion of multiple residues, up to six amino acids, did not fatally abolish its specifi c degradation activity, instead of being able to improve the stability of the tagged protein in the presence of endogenous proteases before mf -Lon expression in E. coli . Except for previously identifi ed essential residues, the region adjacent to the C-terminal of the mf -ssrA tag was involved in mf -Lon and endogenous protease-mediated degradation. Moreover, the deletion of specifi c residues made the mf -ssrA tag more eff ective and compact. The mf -ssrA tag can be implemented in synthetic biology and bioengineering for development of synthetic circuits.展开更多
基金Supported by Medical Specialty Development Projects of Beijing Municipal Administration of Hospitals,No.ZYLX201402Ministry of Education of The People’s Republic of China,No.20121107110012+1 种基金Beijing Municipal Commission of Education,No.11320016Collaborative Innovation Center of Infectious Diseases and Beijing Key Laboratory of Emerging Infectious Diseases,Beijing,China
文摘AIM: To investigate the molecular mechanism for regulation of cholesterol metabolism by hepatitis C virus(HCV) core protein in Hep G2 cells.METHODS: HCV genotype 1b core protein was cloned and expressed in Hep G2 cells. The cholesterol content was determined after transfection. The expression of sterol regulatory element binding protein 2(SREBP2) and the rate-limiting enzyme in cholesterol synthesis(HMGCR) was measured by quantitative real-time PCR and immunoblotting after transfection. The effects of core protein on the SREBP2 promoter and 3'-untranslated region were analyzed by luciferase assay. We used different target predictive algorithms, micro RNA(mi RNA) mimics/inhibitors, and site-directed mutation to identify a putative target of a particular mi RNA.RESULTS: HCV core protein expression in Hep G2 cells increased the total intracellular cholesterol level(4.05 ± 0.17 vs 6.47 ± 0.68, P = 0.001), and this increase corresponded to an increase in SREBP2 and HMGCR m RNA levels(P = 0.009 and 0.037, respectively) and protein expression. The molecular mechanism studyrevealed that the HCV core protein increased the expression of SREBP2 by enhancing its promoter activity(P = 0.004). In addition, mi R-185-5p expression was tightly regulated by the HCV core protein(P = 0.041). Moreover, overexpression of mi R-185-5p repressed the SREBP2 m RNA level(P = 0.022) and protein expression. In contrast, inhibition of mi R-185-5p caused upregulation of SREBP2 protein expression. mi R-185-5p was involved in the regulation of SREBP2 expression by HCV core protein. CONCLUSION: HCV core protein disturbs the cholesterol homeostasis in Hep G2 cells via the SREBP2 pathway; mi R-185-5p is involved in the regulation of SREBP2 by the core protein.
文摘采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、双抗夹心酶联免疫吸附(enzyme-linked immunosorbent assay,ELISA)等方法,以Jug r 1含量为指标,对云南7个不同产地的泡核桃(Juglans sigillata)进行筛选,进一步利用硫酸铵分级沉淀、凝胶过滤层析、液相色谱-串联质谱等手段制备Jug r 1并进行优化和鉴定,通过圆二色谱对Jug r 1的结构进行表征,最后采用双抗夹心ELISA法测定其含量。结果表明:保山隆阳产地核桃的总蛋白含量和Jug r 1含量均最高,用于后续实验;经优化得到Jug r 1的最佳硫酸铵分级沉淀分离区间为40%~80%,进一步对其进行凝胶过滤层析的最佳条件为上样质量浓度30 mg/mL、上样体积4 mL、洗脱流速1 mL/min;在此条件下纯化得到Jug r 1含量达19.90 mg/120 mg上样量,蛋白得率为16.58%;质谱分析表明该蛋白符合Jug r 1的典型特征;圆二色谱显示Jug r 1的二级结构以α-螺旋为主,多种构象共存;经“两步法”分离纯化后可获得蛋白纯度占总蛋白96%以上的Jug r 1。本结果可为深入研究Jug r 1提供科学基础,并为其他坚果致敏蛋白的分离纯化提供参考。
文摘An improved CBB staining with higher sensitivity than that of the typical CBB staining was reported.The main improvement was using a fixing step of 25% trichloroacetic acid(TCA) before CBB staining.For most proteins studied,the sensitivity of the improved CBB staining was about twice as high as that of the typical method.For basic and low molecular weight proteins such as ribosomal proteins,the sensitivity of this improved staining method was about 3.5-28 times that of the typical method.It was speculated that the improved procedure would be suitable for exact quantitative analysis of proteins fractionated by SDS-PAGE,especially for basic and low molecular weight proteins.On the other hand,this new modified method might be also applied to multidisciplinary studies,such as biological researches and nuclear sciences.
基金supported by grants from the Chinese Ministry of Health (2012ZX10001006)the National Natural Science Foundation of China (81271812 and 31370182)+1 种基金111 Project (B08011)the Postgraduate Scholarship Program of the China Scholarship Council
文摘Viral protein R(Vpr) plays an important role in the replication and pathogenesis of Human immunodeficiency virus type 1(HIV-1). Some of the various functions attributed to Vpr, including the induction of G2/M cell cycle arrest, activating the NF-κB pathway, and promoting viral reverse transcription, might be interrelated. To test this hypothesis, a panel of Vpr mutants were investigated for their ability to induce G2/M arrest and to activate the NF-κB pathway. The results showed that the Vpr mutants that failed to activate NF-κB also lost the activity to induce G2/M arrest, which suggests that inducing G2/M arrest via Vpr depends at least partially on the activation of NF-κB. This latter possibility is supported by data showing that knocking down the key factors in the NF-κB pathway – p65, Rel B, IKKα, or IKKβ– partially rescued the G2/M arrest induced by Vpr.Our results suggest that the NF-κB pathway is probably involved in Vpr-induced G2/M cell cycle arrest.
文摘AIM: To investigate the roles and interactions of rhoassociatedprotein kinase (ROCK)1 and miR-124 inhuman colorectal cancer (CRC).METHODS: Expression of ROCK1 protein wasexamined by Western blotting, and quantitativereverse transcriptase PCR was performed to measureexpression of ROCK1 mRNA and miR-124. Two cancercell lines were transfected with pre-miR-124 (mimic)and anti-miR-124 (inhibitor) and the effects onROCK1 protein and mRNA expression were observed.In addition, cell proliferation was assessed via a5-ethynyl-2′ deoxyuridine assay. Soft agar formationassay, and cell migration and invasion assays wereused to determine the effect of survivin on thetransformation and invasion activity of CRC cells.RESULTS: miR-124 was significantly downregulated inCRC compared to normal specimens (0.603 ± 0.092 vs1.147 ± 0.286, P = 0.016) and in metastatic comparedto nonmetastatic CRC specimens (0.416 ± 0.047 vs0.696 ± 0.089, P = 0.020). Expression of miR-124 wassignificantly associated with CRC metastasis, tumor Tand N stages, and tumor grade (all P < 0.05). ROCK1protein was significantly increased in CRC comparedto normal tissues (1.896 ± 0.258 vs 0.866 ± 0.136,P = 0.026), whereas ROCK1 mRNA expression wasunaltered (2.613 ± 0.251 vs 2.325 ± 0.246). miR-124and ROCK1 were inversely expressed in CRC tissuesand cell lines. ROCK1 mRNA was unaltered in cellstransfected with miR-124 mimic and miR-124 inhibitor,compared to normal controls. There was a significantreduction in ROCK1 protein in cells transfected withmiR-124 mimic and a significant increase in cells transfected with miR-124 inhibitor (P s < 0.05).Transformation and invasion of cells transfectedwith miR-124 inhibitor were significantly increasedcompared to those in normal controls (P < 0.05). Cellstransfected with miR-124 inhibitor showed increasedcell proliferation.CONCLUSION: miR-124 promotes hyperplasia andcontributes to invasion of CRC cells, but downregulatesROCK1. ROCK1 and miR-124 may play important rolesin CRC.
文摘AIM To determine the association of human antigen R(HuR) and inhibitors of apoptosis proteins(IAP1, IAP2) and prognosis in pancreatic cancer.METHODS Protein and mRNA expression levels of IAP1, IAP2 and HuR in pancreatic ductal adenocarcinoma(PDAC) were compared with normal pancreatic tissue. The correlations among IAP1/IAP2 and HuR as well as their respective correlations with clinicopathological parameters were analyzed. The Kaplan-Meier method and log-rank tests were used for survival analysis. Immunoprecipitation assay was performed to demonstrate HuR binding to IAP1, IAP2 mRNA. PANC1 cells were transfected with either anti-HuR siRNA or control siRNA for 72 h and quantitative reverse transcription polymerase chain reaction(RT-PCR), western blot analysis was carried out.RESULTS RT-PCR analysis revealed that HuR, IAP1, IAP2 mRNA expression were accordingly 3.3-fold, 5.5-fold and 8.4 higher in the PDAC when compared to normal pancreas(P < 0.05). Expression of IAP1 was positively strongly correlated with HuR expression(P < 0.05, r = 0.783). Western blot analysis confirmed RTPCR results. High IAP1 expression, tumor resection status, T stage, lymph-node metastases, tumor differentiation grade, perineural and lymphatic invasion were identified as significant factors for shorter survival in PDAC patients(P < 0.05).Immunohistological analysis showed that HuR was mainly expressed in the ductal cancer cell's nucleus and less so in cytoplasm. RNA immunoprecipitation analysis confirmed IAP1 and IAP2 post-transcriptional regulation by HuR protein. Following siHuR transfection, IAP1 mRNA and protein levels were decreased, however IAP2 expression levels were increased.CONCLUSION HuR mediated overexpression of IAP1 significantly correlates with poor outcomes and early progression of pancreatic cancer. Further studies are needed to assess the underlying mechanisms.
文摘Plants, just like any other living organism, naturally get attacked by various pathogenic microorganisms such as bacteria, fungi and viruses. However, unlike animals that utilize their specialized circulatory macrophage system to protect themselves, plants instead use a multi-layered complex system termed the plant innate immunity, which recognizes pathogens and transducing downstream defense responses. They have developed a unique type of trans-membrane receptors or R proteins, which extracellularly, are capable of recognizing pathogen-associated molecular patterns (PAMP) such as flagellin and chitin, while intracellularly, they activate their harbored nucleotide cyclases (NCs) such as adenylyl cyclases (ACs), to generate second messenger molecules such as 3’,5’-cyclic adenosine monophosphate (cAMP), which then propagates and magnifies the defense response. To date, only a single R protein from Arabidopsis thaliana (AtLRR) has been shown to possess AC activity as well as having the ability to defend plants against infection by biotrophic and hemi-biotrophic pathogens. Therefore, in order to further broaden information around the functional roles of this protein (AtLRR), we explored it further, using an array of web-based tools or bioinformatics. These included structural analysis, anatomical expression analysis, developmental expression analysis, co-expression analysis, functional enrichment analysis, stimulus-specific expression analysis and promoter analysis. Findings from structural analysis showed that AtLRR is a multi-domain, trans-membrane molecule that is multi-functional, and thus consistent with all known R-proteins. Findings from anatomical and developmental expression analyses showed that AtLRR is mostly expressed in pollen grains and flowers, senescing leaves as well as during the development of seeds, shoots, roots, seedlings, leaves, flowers, and siliques, linking it to the three key plant physiological processes of reproduction, defense and development respectively. Lastly, findings from co-expression, functional enrichment, stimulus-specific expression and promoter analyses, showed that AtLRR is mostly co-expressed with several other proteins linked to disease resistance, plant reproduction and plant development. Activities and functions of such protein are also commonly regulated by cAMP via a common W-box promoter. So, all in all, our study managed to establish that besides being strongly involved in disease resistance against biotrophic and hemi-biotrophic pathogens, AtLRR also plays key roles in plant development (seed, shoot, root, seedling, leaf, and silique development) and reproduction (flowering, and pollen tube growth and re-orientation), whereby it effects its functions via a W-box or WRKY transcription factor, TTGACY, mediated by cAMP.
基金supported by the National Natural Science Foundation of China (No. 21476167 and No. 21778039)
文摘SsrA peptide tag from Mycoplasma fl orum has been developed as a versatile biotechnology tool to control orthogonal degradation of tagged proteins in Escherichia coli . Here, using the systematic deletion mutants of mf -ssrA tag, we demonstrated that the residues in two separate regions have diff erent functions in mf -Lon-mediated specifi c orthogonal target protein degradation in E. coli . The deletion of multiple residues, up to six amino acids, did not fatally abolish its specifi c degradation activity, instead of being able to improve the stability of the tagged protein in the presence of endogenous proteases before mf -Lon expression in E. coli . Except for previously identifi ed essential residues, the region adjacent to the C-terminal of the mf -ssrA tag was involved in mf -Lon and endogenous protease-mediated degradation. Moreover, the deletion of specifi c residues made the mf -ssrA tag more eff ective and compact. The mf -ssrA tag can be implemented in synthetic biology and bioengineering for development of synthetic circuits.
